I want if I do the title of my talk today
a little bit of chemical electronics it's

sort of the equivalent to using
electronic chemistry but not entirely.

And we have been induced field for
a long time.

Seventy five years or so but I will be
also showing some showing some new results

and these are the stream main
sections of my talk organics and

we conduct this in electronics
how they can be used.

And.

How the chemical electronics can
be used for chemical sensing and

in specifically their own of the contacts
between the metals and the organic

semiconductors and water all day play
in this can we thought I thinks so.

The idea of combining chemistry and

solid state electronics name research
economic Tronics is not new.

As I said we have been in it for
thirty five years and there have been from

the very beginning early promises and
expectations that if you look and

produced on the finger you see
the chip in this chip has eight

different chemicals since the field
effect on existence on time and so

it is a right if you want and the premise
was that you could integrate it.

So loosely don't like
Tronics on the same chip.

And.

We would say you know Raggett material but
what came as a bonus later on.

Well is the fact that we
could actually utilize a new

transduction principle that is
the new type of chemical sensor.

So this is the study any promises so
here's the the first slide shows.

The wreck that we have been doing.

Here you have outline of
the insulated gauge field if it

comes is that you could reach.

I do not need to explain to this on.

Yes but what is different here is
that we replace the typical metal.

Aluminum gold or copper or

polysilicon we have replaced this
conductor was organic semiconductor and

this is where the interaction between
the chemistry and electronics takes place.

So what happens here is that when
the vapor penetrates into the bulk of

the semiconductor it changes its
work function where function

is the affinity of the material for
electrons the proper definition is that

it is the energy to do you need to supply
to take the electron and move it out

from the bulk of the material sue
the interface to the vacuum reference

level which means outside the like
to study forces over the material.

And the energy to this.

Required to accomplish this
is called crankshaft and

different materials have different
sort functions one of the fundamental

characteristics of materials and we can.

Broadly speaking say that the noble
materials such as gold or

platinum really do have very high of audio
for a function which means that they

hold on to electrons very tightly on the
other hand to let me know has a low body

of work function or Coliseum or sodium and
so they don't see the ice very easily.

So the work function translates
directly into the chemical properties.

Now we are you theorizing the fact
that the Vendee organic molecules or

you know are going to
be more like your gas.

Enters into the organic semiconductor it
enters into the relationship is the is

the semiconductor in such of a donates or
accept at least partial electron density.

And it forms what organic chemist would
call a charge transfer complex and

that means that.

If the electric the the goddess
electron donor it

will donate part of
the electronic density into.

The semiconductor Now what happens is this
is the density which is either at it or

which is drawn is that it becomes
part of the conduction band it

changes the position of the Fermi
level in the in a semiconductor.

And affirming level is smart of the key
part of the matter is that the term means

the operating correctly sticks of the
transistor namely to traditional to want

H In a traditional thought that you have a
flood potential and you have a difference

between the silicone and that function
of silicone of course that has it's own

going to function and you're going to
semiconductor So if you can modulate.

One component of this old well to each

then we have a transaction mechanism
that allows us to translate the change

in the current drain current into source
current which flows here in this channel.

To the chemical changes that
they place in this specific

electronic configuration which is
called a source follower configuration.

If I change the vent function of the are
going to be contacted by plans hundred

many faults in this particular
configuration the you know to maintain

the same kind of we have to apply in minus
ten one hundred minus handle many faults

from the from the supply and
therefore the output

voltage of that supply now is that direct
measure of discriminately interactions.

In the overview a chemical
interaction of this species Now

let me just point out one thing
because I will not get to it later.

It is possible to put I do things on it.

I don't select if membranes for example
each are used in an so I thought out or

enzyme containing layers and
so be made and

semantic field effect on systems or
I don't select if your defect on system so

this is we had a combination of chemistry
comes in and you can look at it from

the chemist point of view can look
at it from this point on downwards.

This is just a very high
import impedance amplifier.

If you want an impedance transformer.

We simply translates the.

Changes which are taking place in this
chemical layer into electrical current So

this is a very very efficient transducer.

OK So this is the implementation of for
the potential my to

God's sensor which is based on this work
function principle you take an organic

semiconductor you make two contacts
they are identical typically was gold.

And we apply the same gate all cage
which means that there is a coupling

electronic coupling between
the gate material and the and

the organic semiconductor same equation
as you saw in the previous slide which is

the drain to source current equation for
operation of effect in a such ration mode

here is the difference of the very
function of organic semiconductor and

silicone divided by the capacitance
of the the insulator and

for constant drain current we can
rewrite this equation in this form and

then maybe have a chemical
more your nation.

This is the charge transfer complex
formation G. stands for God.

Gas comes in and I had to donate or accept
electrons from the semiconductor you plug

it into the Fermi DAC equations who run it
through the relatively simple algebra and

you come up with the transfer function
which tells you that the gate voltage

you read over here is then related to
partial pressure of gas plus of the sum of

all the other interfering gases and
so this is the fundamental equation

very similar to Mr equation but
it has won a significant difference and

that is instead of a number of
charges which you would have here for

say of potassium I own a car seat of
my own accord and would be alarmed.

Plus one plus two minus one here we
have a fraction of the charge which is

related to discharge transfer complex so
disk is not even a tool for

determining the charge
transfer reaction itself.

This is the implement a.

We have to go to electrodes corresponding
to discuss section this dark outline

is a proxy material which is used only as
a permanent proxy mask which is used to

locate the material that we are interested
in this material in this location and

this is of course the gate and we are
using so you can excite surgical nitrites

typically eight hundred X. terms each
which give us a perfect oscillation.

Even if you want to embarrass it in
a solution which is good because example.

It's a reversible sensor response to
the changes of ammonia in air up and

down and up and down and it's very
very simple very reproducible change.

Not particularly if not lightning fast so

one of the of checked is that we have
looked at to increase the speed of this

action here are the here's the list
of other gases that we have done over

the years you may ask a question why are
we interested in these particular gas is.

And the reason is the answer is
money if somebody pays you for it.

You do it.

OK And so do you swear the sort of a mess
scenario way of looking at doing science.

OK so.

The whole dream and I have started I had
this dream about thirty five years ago.

And I was still pursuing it.

And I am very happy to be
able to do it here because

it was the support of my R. C. and and

support of my own friends
the person my endo and his SO

former student now collaborator
Muhammad but here we have building or

a very actually implemented
the solid state election makes and

coupling it into this coming collect money
it's not a simple straightforward thing

because the fabrication the rules
that you have for the for

the front and for the chemical and
are very different.

First of all use have to use gold
mythology zation and you just.

Not to use that in a regular
city call of foundries

because they just don't like gold but
there are some aspect ratios and

materials that are used that do not
fit into a fabrication process.

So the strategy that we have used and

we tried many different strategies has
been to fabricate this separately and

this chip is fabricated here at M I R C.

And then having an electronic support
chip which may contain thousands of

transistors for
which I am sorry to say the specs and

operations of them I receive not good
enough to do that we go to mostly as we go

to commercial city confound us and
then we need to connect them and

we do that by the technique that has been
developed by a professor of mine and

one hundred back here and
collaborators called C. overeats OK So

let's look at the physics of
the individual devices and

I would like to address the first question
in these induced devices are the contacts

we are not POS in any current between
the organic semiconductor and gold but

yet the contact place a crucial role and

this is sort of a electro chemists
view of looking at the contacts.

If this is the say gold lead coming in and

here is the claim to be to be in
the organic semiconductor and gold.

You can represent this interface
by the interface showing impedance

where you have a double layer capacitance
and charge times very existence.

Now.

In the this of course is the is the gate
off the field effect on SR itself so

this is the city called The arcs and
his is the contact itself.

Now.

You can have two types of contacts you
can have the organic semiconductor

has a different degree of
I only want activity and

electronic conductivity of each means
Holsten electrons and I only conductivity.

And you can make you can change the
composition of this material in such a.

Evaded you can vary duration of
Ione to electronic conductivity and

this is what we have done it is
these devices and published actually

last here that you can change
the ratio of all of the contribution.

All of these sad.

Charge times for resistance.

So if I would completely
cut out the electronic

contribution dismissed it
would have infinite value.

And if dead happens that what you have is
a van capacitor here which is in series

and not a capacitor and so
what you have is a capacity of divider and

that's bad news.

You cannot use capacitive divider for

chemical sensing because any priors it to
capacitance is that you would have and

coupling could be extra static
coupling to the environment

is going to translate into electrical
signals so you absolutely must maintain

a certain finite value of discharge
times very sister at the complex.

So this is this is the material that we
have used for that we have used I only

quickly it's ironically molten salts but
these days you call them.

I only clicker it's not molten salt
because Multan salt is just a repulsive

name and so you these summit throw switch
on nontoxic have zero Luckily they

are very very chemically stable and
they are used this is now a material of

the future or a solvent of the future of
the electro chemist because you can Q.

and A properties depending namely
changing the type of the and I and

in the I don't actually quit so
we are using this particular one.

We are using as an electronic component
is probably alanine And here is a repeat.

You need to fully on
Mt Sinai to a chains and

offending the Rings nitrogen finding
rings oxidized and partially reduced and

India in the course I
just think was I produced

ratio this material is almost
as good a conductor as a copper.

And but it has to.

It has to be don't have to buy and
I own experiences and so

we are using come for so

funny because if you can as many different
assets as a don't print forty's material.

And you see yellow dots here are specific
binding sites which we are introducing and

as a binding sites for
chemical interactions so

these are going on across the US
that we are actually using for

specific interactions of chemical
species the pulley and so this all

electronically couple sort of secular
electrons are very happy about this.

So this is what happens
when we change the ratio

of twenty on in electronic component
to our L. is so room temperature.

Ironically great if I
have a thirty five and

a half more percent of poly identity
in the material is for all intents and

purposes I looked only contracting and
if you do the current voltage drain won't

teach correctly sticks you get almost
ideal care of these sort of solid lights.

OK The did dashed rights are for the case
which I'm going to show you on the next

slide where you actually have
purely a unique conductivity.

The typical characteristic of
the extent as you know is sad.

Drain current against Gates all th and
because of the square in

the in a situation multi
are using square root so for

square root you get a linear dependence
beautiful is our experimental data but

actually fit is the theory perfectly well
and intercept here is the threshold for

all to each of the terms and so
this is what happens when you increase

the content of the I only create
you diminish the pulley on any and

you make it purely on a conducting
what happens is that you get still

a curves that look like a good day
into source current equations.

Except for this thing which is really
experimental artifact then not this thing

it's on us but I'm at this there on H.P.
semiconductor but I'm going to test their.

It's cyclists and there's always
a charge residual charge left over.

And this is the result of THEIR is your
charge totally irreproducible future.

What is even worse is the idea of E.G.

kind of victory stakes
are wandering all over the place.

This was just a snapshot if I
would take it one minute later.

These guys would look
completely different.

So the reason for that is this capacity
had divided it I talked about before

because I don't have enough electronic
resistance to make an electronic contact

and the two capacitors in serious actually
result in this instability in the signal.

So you know that we have
to have a suffocation

amount of I own a contact of it
from different more fractions of.

I only click.

We get a bonus and
that is a speed the transistor response so

no I don't equate this is just
pure Pollyanna I mean I would

have an actively slow response and this is
due to the slow if you should go efficient

in a small it's of Gaza since all it's
There is nothing you can do about it.

However if you make a gel
organic gel of twenty on any and

spend it in I own a quick way to speed
up the response simply because we change

the type of diffusion home which
in use diffusion into quotes and

diffusion very actually to species
penetrate along the point of loss.

And so we achieve if not by order
of my meat you would by a factor.

Faster response.

Also this again shows the times for
equation.

We can get some.

Advantage in getting a little bit lower to
think Should limits the action limit she

was down here to Omonia
again this is long Harmonia

concentration this is the response
care of good looking decent canvas but

changing to different ionic liquids gives
us a possibility of kuning find you.

An interesting points of the material.

So now we are getting into the general
area of chemical electronics.

If I take a organic semiconductor and
put in be between two contacts

deposited on a substrate say Sufiah or
a city going to excite

I can represent the electrical circuit by
I do this by just impedance agreements

I could diagram because at each interface
you have a contact semiconductor

I can represent that by the impedance
of the contact here and contact there.

I have an impedance which is associated
with the interface of the insulator and

organic semiconductor I have
a balk impedance does this one and

I have a surface.

So do use our all in a POS waist to reach
the current can pass from one contact to

an article in fact this is just a simple
care house law but implemented in the AC

domain not just the D.C. if I do D.C.
I could just forget about the capacitors.

So what is actually more
you late to buy even I

need to introduce gas into
this community SR by debate.

This is the cheapest and

not theist also chemical sensor you can
make you just take a bra before going to

be going back to make it two contacts and
publish papers about it.

OK.
The problem is that you can never

interpret their result is coming from
Vegas and the reason for that is that

all of the resistances and capacitances
can be more due lated by I.D.S. and it's

very difficult to unravel the each one of
them securely contributing to the signal.

Now that it becomes organic
few to fix times it's there

it becomes a street terminal device.

Again you have a same structure as we
had before and I want the other end of

the substrate provided the substance
substrate is sufficiently sin.

We can add a metal gate.

Or a silicon gate if you want and
apply electric field and so

what we have is something
to feel more Dulay to

the transfer of the current
between two electoral votes.

By in response to this.

I did electrical field.

And by the generically it is
the same device as a camera SR

except that now we have the search.

I left out and what this additional
few of my delayed indefinitely

stems contact resistance
is back resistance.

Practically every resistance used is maybe
exception of the surface resistance.

So when you think you realized this and

this is already five
years ago four years ago.

Be fabricated here a profit for
me in which we could compare

directly the performance of
the organic field effect on SR and

a silicon based field effect on
SR by creating destruction using

electrodes in a normal eclipse
configuration This is what I have

talked about for the last ten minutes
is that we probably won't if you have

a graphic semiconductor if you measured
the current So in this case the current

flows through silly call this is just a
city called device or is a chemical gate.

However because I have two
electrodes I can prosecute and

sue the organic semiconductor this
regard to drain and source here and

use the substate as a gate material and so
I can pass current through the we're going

to contact the OK so in these two
configurations you're going to conduct.

Their acts as a process material
I would call this passive and

this is active material because
it actually has to carry current.

And the requirements on the contacts
are very different to configurations.

OK Now as Sat and
this is actually the photograph of

the chip that is fabricated here you have
a boarding pass for the two electrodes and

individual gate so
that we can establish many of them.

We can investigate many of them.

Know as any kind of tool to discard

to lice also OK And the reason that it
lies is that it shows the device in a.

Plainer configuration but it actually does
not work that way and I will show you

the difference in a minute but first thing
that we investigated is what is the effect

of a resistance any resistance that I put
in a series between drain and source and

you can do this experiment very
simply by for example oxidizing

forming a seal layer of silicone dioxide
in the contact before you actually do the.

The contact the whole etching and
you can actually add resistance

in series and what we did is that we
created a transistor silicone time sister.

Which happened to have a certain kilo mm
contact resistance due to the city called

oxide and this is what the characteristics
look like use our experimental data

insulated good insulated gauge field
effect on SR This is during current

drain to source won't teach this
region is called such ration this is

a linear each and this is what the cars
look like for different gates all teaches.

The current gate.

They encourage and Gate them all to each
characteristic its over here and this

is the lot which is most important for
chemical sensing or for signal detection.

If I take a lot of it.

The look you would generally dysfunction.

I am showing Davis to show that when you
are reading papers on a field effect

on systems of any kind.

You can just to visually look at this.

And immediately see almost immediately
within seconds you can see what is

strongest said number of the data.

If I have a certain Kilmer's is to due
to the oxide the drain current does not

start rising immediately but there is
an induction period because seemed

to punch through that
oxide in order to get it.

Basically to the same drain
current can actually stick so

here you have a contact resistance
as one or the other contacts or

both and are internal is the resistance
of the semiconductor a material.

The idea of his even more sensitive
because what you have here is this for.

Flattening now.

I D.V.D. curve as it is does not
go to infinity is through the roof

like this it eventually eventually
flattened soft but it's for

quantum mechanical reasons due to
the development of such a ration and.

But that's not what I'm
talking about here.

Here I am talking about
a real resistor in series and

what happens is as you can see here.

If the the by application
of the gate will teach.

I am decreasing the contact as distance
that is increasing the current.

And the resistance becomes.

If the current becomes very high
then of course the resistance

becomes comparable because
factorizations becomes comparable.

And it's no longer modulated contact
assistance in this case is not what you

lated by the gauge field.

So we started looking at what kind of
resistance this we can account and

counter in diesel going to
semiconductor materials.

If I have a good pulley on any.

I have a sensually let me contact
that I have also make contact in

a gold point to St I often put six feet
as a favor one of the favorite materials

you are going to examine conductor people
and this is just a fancy way of writing

a Ohms law because of the constant
this constant temperature is constant.

So this is constant and this is just
a current is proportional to conductance.

OK So this is only this
is only contact if I have

a layer of Excite so
aluminum aluminum oxide poly on any and.

What I have to do is to punch
through that oak site and

this is departing is described by
the following Norheim equation and

the remarkable thing is that there is
a square dependence on the upright won't

be so this is one of the simplest equation
by which to describe a dirty called back.

OK.

If you have a.

A metal and
a semiconductor in going back to this and

that a semiconductor the barrier
that you are looking at

is given by the shopkeeper out here and
a Shockey body has its own equation here.

And again it has a normally
any other function off.

The applied twenty.

And the first type of container there
probably are more is that if I would

have a Komi I'm excited and titanium
will excite the communal excitement

by any more excited by this material it's
sort of a course I semiconductors and

in death case you have a so-called
Frankl Poonam a kind of some

very ugly Stone has to hide from
on a chilly look to another and

they too little but it still has to toggle
between different energy levels and

again the process is described by
the Frankel to make only some.

So these are things that may happen at
the interface of the compact itself and

the electric chemist would call
it a charge transfer resistance.

Now.

The many many times.

Most of the times the organic field effect
on sisters are implemented in the current

play in a form which means that the in
thirty days delicto is in thirty two.

Then after which is this.

Depreciated on the insulating substate.

And then the gate is supplied from
the bottom and this insulating substate.

Has electrodes corresponding to drain and

source so it would be drained
this would be this is source and

this is a drain going towards you.

If I know a private dangerous
source won't H. do it.

I create a link to field between
these contacts to the organic

semiconductor on the insulator.

Now then I applied the said electrode.

The electric field now has a Victorio
addition here at the contact.

And this.

This vectorial edition actually
applies to all the normally near

the electric fields which is at this
contact actually applies to all

the non ideal contacts that I showed on
the previous slide but it's hard or time.

Frankl poorly shot came
a kind of them all.

I don't mean here and only respond to the
presence of the selected field which is at

the contact and it is only because
the contacts are in the same plane

as the organic semiconductor
in a normal device.

In a normal city call I'm
sitting on public aid it fat.

You would have the contacts would be
removed from the electric field by

so-called field oxide and this is why I
said the cartoon that I showed you before

law is because they're each show
as an equal play in a device.

Well in order to dig into this deeper.

The fabricated here again of them.

I asked C.V. fabricated to structure
use a four point program this

past form here are the five electrodes
are to feed a electrodes and

the two electrodes in the middle
are appropriate Actos So

here is feeder here so
not a feeder here are pro but

I know it's the current process only
some of the feeder electrodes and

here are measuring the well to stop this
is a normal four point probation meant

which most of you are familiar is however
what the added here is that we implemented

it on a city on eight hundred X.
himself oak site and eight hundred M.

sense of night tight and
put a metal like toilet on the other end.

Therefore we can actually feel
more due late because Fairpoint

broke measurement and
what do you think I was a stood do.

Of course is to examine the effect
of electric field on the behavior

of individual contacts so here's
a summary it's a business like OK so for

a normal organic field effect
on SR I will be processing.

Well to each between the kind and
between drain and

source ignored it is for the time being.

So the current runs this way and
so the current and

contrasts three years distances
in serious the drain or system.

Organic semiconductor assistance here and
a source for assistance.

I can also run a base.

In the following way.

I can I can apply you won't teach
between if you don't like toads and

just to measure the voltage drop between
source code I'm still source and drain but

there is no current flowing
through the selector with and

therefore I have isolated the their
insistence only through the organic semi

contracted this is the normal four point
broke my human eye can do a lot more take

and I can ignore this electrode I
can positive alter the kind and

sue the day and
I could go into the exuberantly.

Gowned.

No current process so here and therefore
I have isolated Stuart as distances here

drain assistance and
organics semiconductor assistance and

I can do the same trick symmetrically
was the source resistance.

So by doing days saddest thing I have four
equations beach and allow me to isolate

individual contributions to the current
industry to assist the serious.

OK So as far as I know this is the first
time it has been it's not it's a little

bit tricky saying because
these devices are quite large.

This is.

Here we are talking about.

About a centimeter by centimeter chip.

And what you definitely do not want
to have is a leaky each car and

between the pride gauge will teach and
the and the and the outside.

So the quality of the insulator
has to be very very very high.

You cannot afford to have
a defect density in such and

many devices as you make
it that even in a careful.

Carefully prepared positive ation layer
you still have a leakage current So

discard it.

So every time we do the measurements
we make sure that we do

not have a significantly each
current between the gate and.

OK.

So for a normal on foot operation
when you have it like this.

You pass the coming from the drain to the
source through we're going to make contact

you see only three resistances and these
are typical published carobs hundreds

of papers on organic field effect on
systems showing these kinds of keris OK.

Bearing in mind that they actually
represent all street insistences.

But then we do the field
more you lation and

we can actually see how do you suppose
instance change its existence is change

in terms of gait the well to each applied
gate twenty's this is what we see.

This is the overall resistance of
the field effect of the of the OFA it

is the blue line.

But the major contribution by far
the biggest contribution is from the drain

contact not from the organic
semiconductor OK and

we will go see if explain a little
the organic semiconductor if SAT is so

not a very minor contribution but

still it does contribute
the damed contact with the fusion

to the field is very high very little
contribution from the from the source.

If I if I did.

Now do the measurement as it should
be data processing the kind of

studio's electrodes and
just reading the whole teach here.

I would say OK well this is just a drain
of all teach applied here between

drain and source and here is the more you
action of the organic semiconductor decide

because that you would get from that
you cannot actually achieve a total

such ration because the same
thing applies here.

You actually form a pinch off but
we are not going to the details but

you can calculate from that the idea
of E.G. curve and the idea of E.G.

kind of her look surprisingly as a curve
to it you would off thing in the normal

enjoyed it gave feel effect on just a not
quite not quite it is sad it is again and

highly normally near Aleisha it cheap.

So now electrochemistry I took him is
by training and so I look at the wrong.

SU electric at my size.

If you make so called The Band
electro now bent on October is a line

of metal immersed in
the electrolyte embedded

this is what I mean by immolate actually
embedded in the insulating plane.

OK so you have a band of metal insulating
play and you have a electrolyte and

you perform some electrochemistry on it.

This is the current that you will of taken
from that band electrode find a constant

diffusion go fish and concentration of the
species lengths of the the the the line

again diffusion go fish and
and of it's of the light.

But there is a key here and
theists and these are the T.

is in the library from is the time
dependence in other words the band electro

built continuously decrease
the current and the reason for

it is that it forms so-called to be police
employees ation depletion as you other

two lights you remove the species and this
does depletion layer extends farther and

farther and farther away and
it's a because it doesn't look at me to

get this open and its function
fundamentally cheekily you can you cannot

divide the you can now plug it
into the basically Ohms law and

not say in a finer moment Szekely similar
equation from desegregation he's here but

instead of having
a voltage applied won't it.

Here I have electric field which is
selected field multiplied by deed

the sickness of it is depletion lair and
this I like to field is now

composite of two different fields drain
to source field created by applying

to voltage between drain and source and
the gate field and as you know the field

addict Tauriel which means it depends
on the geometry of the contact.

If I have a contact which is in the light
then it is going to look German the few.

It is going to look very different than if
I have a metal deposit it as a basically.

As a rectangle as a bar on top
of the electrode So you have to.

And if you fabricated one day in
the laboratory you will get one type of

contact and I did a different
type of contact and I don't know

about that a completely different want
to do since this is what explains great

about islet variability over the date
up least in the early thirties so

what is the difference between
the operation of a credit and the OFAC.

And this is what we believe is
happening in a cut in a situation

mode where you have formed this is called
a pinch off point where you only do such

a great thing here you have
a ballistic transport.

Over the minority carriers from
a drain into the depletion layer.

But.

Because it is it is built on and
type silly called.

There is still a conduction beaches and

type in the city called present here so

you have a conductor here but
you have only depleted the holes.

In the organics.

So this is equivalent to
electro chemical experiments of

performing electric
chemistry in the presence of

supporting electrolyte no presence
of supporting electrolyte means that

I have always a conducting I only click
conducting species in a solution.

I don't know I am depleting
get the oxidizer bill or

a deuce of a species said
the electro I still have and

conducting region in between so they snow
I like to feel do you cannot have electric

field in the in the presence of the of
the conductor I only contact it not so

in the organic field effect on system
in the organic field effect on SR.

You have all new Lama type
of carious in despoiling or

in poignantly any had a similar
going back to each other.

Mostly P. type materials you
are depleting the carrier.

Are depleting the holes and
once you have depleted the home so

you have nothing you have an insulator.

And then you have an insulator
you create an electric field and

this electric field now adds
to Victoria only in the.

This is the electric field
now we just modulate

the resistance of the of
the polarization of the contact.

And some of this is
the reason why are you.

At the drain contact that you
are consuming to select out and

you are creating this
polarization resistance R P.

You are actually creating a region
which is vulnerable to external

electric fields and
this is what accounts for

the modulation of the signal in
the organic field effect on SR so

is organic food effect on existed the same
as silicone field effect transistor.

Well only if you go back to shuck place or
original definition of the time.

SR and that is time SR is
a voltage regulator transistor.

So in that sense yes this is a field
effect on SR but it is not a.

You cannot use the I expect equations
to elevate anything from it.

This is just to illustrate a point.

This is one of our chips
liftoff this this bar

is half of Micron and
you can see that no matter what you do if

you do if you are using lift off
you end up is a very not ideal.

Joe metry of the contracted
functions perfectly well but

it simply creates an electric field
which you cannot define in any way.

So the summary of this
section is that the.

The field is more you lated
both at the interface and

mostly mostly at the train contact.

So let us then not about twenty years

ago now maybe a little bit longer the
paper started appearing that you can do so

getting food effect on just as chemical
senses the sad part of chemical sensing is

that if you have something
that doesn't bark and

you do not know what to use it for
you use it as a chemical sensor.

And so this is there is just
now a major field organic

field effect on this just as chemical
Sensis So second that it don't plants.

Namely water vapor and
don't accept the gases effect.

This is a very interesting experiment here
we have Chip Reese to been collecting.

Nothing added on it just so we called
nitrite very clean silicone I tried

surface and we would expose it to
work a vapor we call hydrated.

All of you would then bake it in the open
for twelve hours at ninety degrees and

remove the water from the surface and
here is the drain current the gate will

teach not nothing else applied here and
you just have a migration of the surface.

I and some to city clothes and this is
something that has been noticed already

by Want to Sheckley in any
fifties about sixty but

I thought I had started
already in early fifties.

That this course is the crosstalk
in a city called devices.

And this is why you have to pack each and

encapsulate properly in order to protect
the surface of the Arc Sight surfaces

from the rock up oxygen
oxygen is a is a bad news.

So OK so here you have an old friend
passing the current through this and

beautiful keris venue.

After you have and they want it.

This is beautiful.

After one hour exposure this is
politics so they often after

one hour exposure the cutting the
increases note is the change this is for

four or four tenths of my crammed
this is ten times slower current

in the annealed device OK again
immediately after costing

you get caught in full to the day kind
of engagement each care for like this.

Here you have after any link I
needing removed oxygen you get

a beautiful characteristics which
means if you have room to have

any chance of running the we're
going to feel different.

The fans are going to defect I'm
just as a device you have to remind

folks you know you have to protect.

So this is what we have done is
this material pummelled It's

a special insulating material
which is alone permeability but

it's not completely black oxygen
access this is fair point.

Broke my shipment which means POS in kind
and between almost you know electrodes and

measuring here.

And you have more delays.

Yes Days on what your nation do to
the gate voltage but nothing that would

like it cut in full to each mission
gatefold each measurements kind of.

Doing kind of gauge oldish
measurement that he would up to and

from the two point placement.

So on off on off right here.

It's very important for
we're going to collect tonics.

And it decreases in terms of days
then days if you expose it to oxygen.

It goes to two Halley just doesn't
work as a switch anymore because.

The ratio just degrades social
policy chief says Wow So

there I'm beyond effects.

This is our model for
what is happening is the the oxygen and

moisture degradation of twenty six.

OK if you know five.

If you expose it to ambient conditions.

You didn't rub his back Boss way you
actually processing the current in

the bottle credit at the interface and
so it competes for

any more you lation that you
may have had the interface.

So if you smoke you like it that the on
foot by electric field interface and

brain contact by chemical means
balck contact and the interface.

In summary.

Organic semiconductors have been used and

can be used as a POS if
layers in the comfort.

This is to use it as a gate material.

Or act if which means current POS ink
devices in a chemical electronics.

The I want to stipulation on the quality
of the organic semiconductors

in comfort is the electronic
connectivity you have to have

a electronic communication between
the metal and there are going to material.

Modulation of organics.

Conducting on foot is by a very function
and by conductivity because the oxygen.

And I don't.

Materialists will contribute as well.

This is the absolute truth.

That the the critically
actions cannot be used to

evaluate the carrier mobility
in measurements period.

I think that if our results
clearly showed it and

I do people have actually
are finding that this well.

And all fits one Apple two chemical you
lay should by ambient this chemical census

office do not offer any advantages
over chemist S. and conclusion.

The fact that you have the other
tournaments and the organic semiconductor

in the same plane subject to the same
electric field is the quote primary.

It is the.

It is the the course of the problem.

Now is there whole P.S.U. could actually
make organic food effect on a system but

you would have to synthesize material
that would have boast a minority and

to make sure you don't put in smoke by
I don't dance in the same material and

that's organically very difficult task to
do but yes it is possible to do it so.

You would have to do that and

the office can be used only as active on
or off devices you can never use them as

I don't know the devices as long as they
are protected against the ambient effects.

Now I need to acknowledge people most of
the work that has been done here is by

having Chen who is still working on
my R.C. as was his P.H.D. work and

care is working on
the interconnect there so

despite all the comfort
of their matches so

may just be in for us involved in
the synthesis of meant to us and

electrochemistry what your common
source in the Manstein the oxygen

barrier materialists and in a discussion
of the physics of these devices.

I don't know about how fabricated the.

Fairpoint problem field more united
four point zero measurement and

I mean if so have.

West on a very quickly.

I only play quits.

Now I have added Paul call on this
NG only because I'm not involved in

any of this and I cannot blame him for any
of the stuff that I presented here but.

We had a awfully difficult time getting
despite it took me two years to get this

through one channel after another channel
because this is a symptom of a gang

the people who work on the open.

It's do not like to know
it would be working on it's

really not what they think
they are wrecking on and so

finally I had to sit down was Paul and
he could very kindly.

Be understood to be
discussed everything and

he agreed to publish it in a chat
with electro chemical society so

the key paper for this work was
published in General Chemical Society.

And I thank you very much for
listening and

I would be very happy to answer questions.

How

do you want to carry on what you simply
have made them publish devices so

that you incorporate into point of play.

Do you believe you will communicate.

Your module a direct function by hydrogen
and what you later work function off.

Of palladium that's like a champ over.

We have seven decades of dynamic range and
a very fast sensor.

Why do you ask about.

Well

first of all you get money if
you go to nano scale right but.

I don't see any of the physics is going
to stay the same you still have to

somehow have to make a contact between
the electronics which is the metals or

polysilicon.

And you're active material which is
organic semiconductor you have to have

a contact.

The dip of the depletion layer very much
depends on a diffusion kind of fish and

so when you go to not know the sinks
are beginning to cross over.

OK so there may be a different
physics involved simply

because of the geometry of the device but
I have not really looked into it.

I do not see I do not
expect any advantages

one

will get

and the status of what we are waiting for
to become operational so

that we can actually connect the.

Fabricated which we have tested and

the most this chip which we have
already up like nine months ago.

Nine months ago.

OK we can get a fifty one toward

the status OK we are ready for
the chemical testing which.

You know yes

yes I hear you on your silly billy think

possibly Well OK the ammonia the response
to ammonia comes from poorly on nearly.

The I only think width is
just a transfer medium.

OK so what you are talking
about is a diffusion coffee and

some ability which are different for
different ironically quits be

like this one because you know as you know
it's a little bit of a pain in the neck to

synthesize and purify and you really
have to purify and look like it's so

this is the one that we invested in and
this is the one with the try here first.

Yeah.

Possibly but as as I showed in
a table of different gases.

If you give me a hundred K.
I will make you a sensor for that.

It's it's my night here.

Yeah he's here he's here.

Just think they can.

OK

because

he

wasn't a question or comment.

Well OK is no.

What is true anything at me at that
point so I assume that at least here

no we do not have a style when she came
here as a store person in the audience.

I what I'm talking about is interpretation
being able to interpret what is

actually the origin of your responses in
chemical sensors no matter what you make.

OK No MAF sensor optical sensor or
anything it then of a series.

Points to something that
you screw it right.

For Dad There are generals we specialize
in a description of don't type of

Vereker where you get some kind of a
response and you publish it and that's it.

You have no idea where it is coming from.

In my opinion that has a very little
value because it becomes very

vulnerable to inadvertent changes of.

Well this is the case of this is the story
of the camera system or organic field

effect transistor you just to have no
idea where the signal is coming from.

So I'm contrast ing it little bit is the
CAMFED because I know that the only way

you that I can get is from
the work function changes and

I can describe it by equations.

Well I appreciate the invitation
thank you very much.