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

The instability in the electrical properties of 4H-SiC(000 (1) over bar) C-face metal-oxide-semiconductor (MOS) systems processed by wet gate oxidation with H-2 postoxidation annealing (POA) was characterized. Wet-oxidized 4H-SiC C-face MOS capacitors indicated a large flat-band voltage (V-fb) shift owing to gate-bias stressing, but a H-2 POA process improved the Vfb shift significantly. The threshold voltage (V-th) shift of wet-oxidized 4H-SiC C-face MOS field-effect transistors was reduced greatly to one-tenth by using an appropriate H-2 POA process. These samples also indicated a high channel mobility (mu(fe)) of 70 cm(2)/(V.s). The coexistence of small V-th instability and high mu(fe) was achieved. (C) 2012 The Japan Society of Applied Physics