Search

We developed an AlGaN/GaN heterojunction phototransistor with a recessed detection area to enhance the photoresponsivity. The recessed-AlGaN/GaN phototransistor exhibited a maximum photoresponsivity of 1.6 × 107 A/W at 375 ㎚, which was ~30% higher than that obtained with a conventional AlGaN/GaN phototransistor. A comparable photoresponsivity was also achieved at 260 ㎚ in UV-C range due to the dual absorption process in conjunction with the polarization induced built-in electric field characteristics of AlGaN/GaN heterojunction.

We have investigated the channel mobility of AlGaN/GaN-on-Si recessed-metal-oxide-semiconductor-heterojunction field-effect transistors (recessed-MOS-HFET) with SiO 2 gate oxide. Both field-effect mobility and effective mobility for the recessed-MOS channel region were extracted as a function of the effective transverse electric field. The maximum field effect mobility was 380 cm 2 /V·s near the threshold voltage. The effective channel mobility at the on-state bias condition was 115 cm 2 /V·s at which the effective transverse electric field was 340 kV/cm. The influence of the recessed-MOS region on the overall channel mobility of AlGaN/GaN recessed-MOS-HFETs was also investigated.

This paper reports a new method to enable the normally-off operation of AlGaN/GaN heterojunction field-effect transistors (HFETs). A capacitor was connected to the gate input node of a normally-on AlGaN/GaN HFET with a Schottky gate where the Schottky gate acted as a clamping diode. The combination of the capacitor and Schottky gate functioned as a clamp circuit to downshift the input signal to enable the normally-off operation. The normally-off operation with a virtual threshold voltage of 5.3 V was successfully demonstrated with excellent dynamic switching characteristics.