(Georgia Institute of Technology, 2007-06)
Abel, Mark R.; Wright, Tanya L.; King, William P.; Graham, Samuel
Thermal metrology of an electrically active silicon heated atomic force microscope cantilever and doped polysilicon microbeams was performed using Raman spectroscopy. The temperature dependence of the Stokes Raman peak location and the Stokes to anti-Stokes intensity ratio calibrated the measurements, and it was possible to assess both temperature and thermal stress behavior with resolution near 1µm. The devices can exceed 400 C
with the required power depending upon thermal boundary conditions. Comparing the Stokes shift method to the intensity ratio technique, non-negligible errors in devices with mechanically fixed boundary conditions compared to freely standing structures arise due to thermally induced stress. Experimental values were compared with a finite element model, and were within 9% of the thermal response and 5% of the electrical response across the
entire range measured.
(Georgia Institute of Technology, 2007-01-01)
Lee, Jung Chul; Wright, Tanya L.; Abel, Mark R.; Sunden, Erik Oscar; Marchenkov, Alexei; Graham, Samuel; King, William P.
This paper reports the thermal and electrical characteristics of a heated microcantilever in air and helium over a wide range of pressures. The cantilever heater size modulates thermal conductance between the cantilever and its gaseous surroundings; and the Knudsen number, Kn characterizes this thermal conductance. When Kn<1, thermal transport from the cantilever heater depends on gas pressure, and when Kn>1, thermal transport from the cantilever heater remains constant. This measurement of thermal conductance around Kn = 1 could aid the design and analysis of Pirani sensors and other microscale thermal sensors and actuators.
(Georgia Institute of Technology, 2006-01)
Sunden, Erik Oscar; Wright, Tanya L.; Lee, Jung Chul; King, William P.; Graham, Samuel
This letter reports the localized room-temperature chemical vapor deposition of carbon nanotubes (CNTs) onto an atomic force microscope cantilever having an integrated heater, using the cantilever self-heating to provide temperatures required for CNT growth. Precise temperature calibration of the cantilever was possible and the CNTs were synthesized at a cantilever heater temperature of 800 °C in reactive gases at room temperature. Scanning electron microscopy confirmed the CNTs were vertically aligned and highly localized to only the heater area of the cantilever. The cantilever mechanical resonance decreased from 119.10 kHz to 118.23 kHz upon CNT growth, and then returned to 119.09 kHz following cantilever cleaning, indicating a CNT mass of 1.4×10 ⁻¹⁴ kg. This technique for highly local growth and measurement of deposited CNTs creates new opportunities for interfacing nanomaterials with microstructures.