This paper presents an in-depth theoretical examination of graphene-based field effect transistors, looking at thermal statistics, electrostatics, and electrodynamics. Using a first principles approach, the unique behavior observed in graphene-based field effect transistors, such as the V-shaped transfer characteristic, limited channel pinch-off, and lack of off-state (under gate modulation), are described. Unlike previous attempts, a description of both drift and diffusion currents in the device is presented. The effect of external resistance on steady-state and high-frequency performance is examined. Comparisons of the theoretical results to experimental results are made and show good agreement. Finally, the theoretical work in this paper is used as a basis to discuss the possible source of some observed behavior in practical graphene-based field effect transistors.

In this report, we study the effectiveness of hydrogen plasma surface treatments for improving the electrical properties of GaSb/Al2O3 interfaces. Prior to atomic layer deposition of an Al2O3 dielectric, p-GaSb surfaces were exposed to hydrogen plasmas in situ, with varying plasma powers, exposure times, and substrate temperatures. Good electrical interfaces, as indicated by capacitance-voltage measurements, were obtained using higher plasma powers, longer exposure times, and increasing substrate temperatures up to 250 °C. X-ray photoelectron spectroscopy reveals that the most effective treatments result in decreased SbOx, decreased Sb, and increased GaOx content at the interface. This in situ hydrogen plasma surface preparation improves the semiconductor/insulator electrical interface without the use of wet chemical pretreatments and is a promising approach for enhancing the performance of Sb-based devices.

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Antimonide-based p-channel HFETs with a 0.25 mm gate length have been fabricated with an InAlSb=AlGaSb barrier and a strained In 0.41 Ga 0.59 Sb quantum well channel. The modulation-doped material exhibits a Hall mobility of 1020 cm 2 =V s and a sheet density of 1.6 Â 10 12 cm À2. The devices have a maximum DC transconductance of 133 mS=mm and an f T and f max of 15 and 27 GHz, respectively. These values are the highest reported to date for this material system.

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