Fabrication and characterization of the normally-off N-channel lateral 4H–SiC metal–oxide–semiconductor field-effect transistors**Projcet supported by the National Natural Science Foundation of China (Grant Nos. 61404098, 61176070, and 61274079), the Doctoral Fund of Ministry of Education of China (Grant Nos. 20110203110010 and 20130203120017), the National Key Basic Research Program of China (Grant No. 2015CB759600), and the Key Specific Projects of Ministry of

Abstract

In this paper, the normally-off N-channel lateral 4H–SiC metal–oxide–semiconductor field-effect transistors (MOSFFETs) have been fabricated and characterized. A sandwich- (nitridation–oxidation–nitridation) type process was used to grow the gate dielectric film to obtain high channel mobility. The interface properties of 4H–SiC/SiO2 were examined by the measurement of HF I–V, G–V, and C–V over a range of frequencies. The ideal C–V curve with little hysteresis and the frequency dispersion were observed. As a result, the interface state density near the conduction band edge of 4H–SiC was reduced to 2 × 1011 eV−1·cm−2, the breakdown field of the grown oxides was about 9.8 MV/cm, the median peak field-effect mobility is about 32.5 cm2·V−1·s−1, and the maximum peak field-effect mobility of 38 cm2·V−1·s−1 was achieved in fabricated lateral 4H–SiC MOSFFETs.