Suppression of Short-channel Effects by Double-gate Double-channel Device Design in Normally-off AlGaN/GaN MIS-HEMTs

In this work, we have performed numerical simulations of normally-off AlGaN/GaN recessed Metal–Insulator-Semiconductor or MIS-HEMTs. A double-gate double-channel device design is proposed and analyzed using calibrated TCAD models. The dual-gate geometry is shown to provide an enhanced gate control over the double-channel, thereby suppressing the short-channel effects. The proposed device exhibits 72-mV/decade subthreshold slope, which is 50% improvement compared to the single-gate single-channel device with 3 µm gate length. Both the double-gate double-channel and single-gate single-channel structures are compared for their ability to counter short-channel effects in aggressively scaled MIS-HEMT devices. It is shown that, double-gate design is superior to single-gate single-channel device with 80% improvement in drain-induced barrier lowering at sub-micrometer gate lengths.