High-mobility enhancement-mode 4H-SiC lateral field-effect transistors utilizing atomic layer deposited Al2O3 gate dielectric

Lateral metal-oxide-semiconductor field-effect transistors (MOSFETs) have been fabricated on 4H-SiC utilizing deposited dielectrics and gate-last processing. The bilayer dielectric consists of thin nitrided SiO2 covered by 25 nm of Al2O3 deposited using atomic layer deposition. Field-effect mobility and threshold voltage (VT) vary with SiC nitric oxide (NO) anneal temperature. Peak mobility of 106 cm2/V⋅s was obtained with corresponding VT of 0.8 V. The peak mobility decreases to 61 cm2/V⋅s with a lower temperature NO anneal, while the VT increased to 1.4 V. Thus with proper gate engineering, high-mobility normally off MOSFET devices can be obtained, leading to higher-performance gate-controlled power devices.