Static Performance and Threshold Voltage Stability Improvement of Al2O3/LaAlO3/SiO2Gate-Stack for SiC Power MOSFETs

Lateral metal–oxide–semiconductor field-effect transistors (MOSFETs) are fabricated on 4H-SiC utilizing deposited high- ${k}$ gate dielectrics. The high- ${k}$ gate-stack consists of thin nitrided SiO ₂ and 40 nm of LaAlO ₃ covered with a thin Al ₂ O ₃ cap. The high- ${k}$ gate MOSFET achieves a 40% reduction in channel resistance (at ${V}_{gs} = 15$ V) compared with that of the conventional SiO ₂ gate MOSFET. In addition, bidirectional transfer characteristics of the high- ${k}$ gate MOSFET indicate slight hysteresis and show a superior threshold voltage stability compared to that of competitors, in a range of −15 V $\le {V}_{gs} \le16$ V under room and elevated temperatures. Therefore, the Al ₂ O ₃ /LaAlO ₃ /SiO ₂ gate-stack can provide both low on-resistance and good threshold voltage stability for SiC power MOSFETs.