The electrical characteristics of a 4H—silicon carbide metal—insulator—semiconductor structure with Al2O3 as the gate dielectric

Abstract

A 4H—silicon carbide metal—insulator—semiconductor structure with ultra-thin Al2O3 as the gate dielectric, deposited by atomic layer deposition on the epitaxial layer of a 4H—SiC (0001) 80N−/N+ substrate, has been fabricated. The experimental results indicate that the prepared ultra-thin Al2O3 gate dielectric exhibits good physical and electrical characteristics, including a high breakdown electrical field of 25 MV/cm, excellent interface properties (1×1014 cm−2) and low gate-leakage current (IG = 1 × 10−3 A/cm−2@Eox = 8 MV/cm). Analysis of the current conduction mechanism on the deposited Al2O3 gate dielectric was also systematically performed. The confirmed conduction mechanisms consisted of Fowler—Nordheim (FN) tunneling, the Frenkel—Poole mechanism, direct tunneling and Schottky emission, and the dominant current conduction mechanism depends on the applied electrical field. When the gate leakage current mechanism is dominated by FN tunneling, the barrier height of SiC/Al2O3 is 1.4 eV, which can meet the requirements of silicon carbide metal—insulator—semiconductor transistor devices.