High-K gate dielectric depletion-mode and enhancement-mode GaN MOS-HEMTs for improved OFF-state leakage and DIBL for power electronics and RF applications

The characteristics of high-k gate dielectric depletion-mode and enhancement-mode GaN MOS-HEMTs is reviewed. High-k gate dielectric depletion-mode GaN MOS-HEMT with thin AlInN polarization layer of 2.5nm in the gate stack is shown to exhibit "negative" capacitance and steep SS<;40mV/dec [31], which may have implications for low-power electronics. Enhancement-mode operation is achieved by removing the AlInN polarization layer from the gate stack [31-36]. Excellent DIBL, low I_OFF, low gate leakage, and low R_ON are achieved due to the scaled Toxe=23Å using high-k gate dielectric and N+ regrown InGaN source/drain [32]. The DIBL and I_OFF-R_ON characteristics of the high-k enhancement-mode GaN MOS-HEMT [32] are the best reported for a GaN transistor. These characteristics make the high-k gate dielectric depletion-mode and enhancement-mode GaN MOS-HEMT attractive for power electronics and RF applications.