Coexistence of Small Threshold Voltage Instability and High Channel Mobility in 4H-SiC($000\bar{1}$) Metal–Oxide–Semiconductor Field-Effect Transistors

The instability in the electrical properties of 4H-SiC(0001) C-face metal–oxide–semiconductor (MOS) systems processed by wet gate oxidation with H2 postoxidation annealing (POA) was characterized. Wet-oxidized 4H-SiC C-face MOS capacitors indicated a large flat-band voltage (Vfb) shift owing to gate-bias stressing, but a H2 POA process improved the Vfb shift significantly. The threshold voltage (Vth) shift of wet-oxidized 4H-SiC C-face MOS field-effect transistors was reduced greatly to one-tenth by using an appropriate H2 POA process. These samples also indicated a high channel mobility (µfe) of 70 cm2/(V·s). The coexistence of small Vth instability and high µfe was achieved.