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World's Best Enhancement Mode, Inversion-Type GaN MOSFETs

Fig. 1. Output I-V characteristics of long-channel (20um), circular GaN MOSFET.
CPES researchers have demonstrated the world's best ion-implanted, enhancement mode, n-channel GaN MOSFETs on p and n GaN epi on sapphire substrates. The maximum field-effect mobility of 167 cm2/V-s, minimum subthreshold slope of 170mV/decade and blocking voltage up to 1kV have been measured. The much improved MOS properties were first obtained on GaN capacitors with optimized oxide deposition and annealing conditions. Researchers have discovered that the interface state densities are much lower near the conduction band edge than those near the valence band in GaN, quite different from those in Si and 4H-SiC. This trend also implies that it is more difficult to demonstrate p-channel devices than n-channel devices. Furthermore, this progress in n-channel MOSFET is a major step forward on the ultimate demonstration of high-voltage MOS-gated bi-directional switch in GaN.

Fig. 2. Schematic cross-section of the ion-implanted, enhancement mode GaN MOSFET.
Fig. 3. Microphotographs of circular and linear devices.
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