Fundamental characteristics of SiC MIS structure with Al<sub>2</sub>O<sub>3</sub> as gate dielectric

Abstract

SiC MIS structure with ultra-thin Al2O3 as gate dielectric deposited by atomic layer deposition (ALD) on epitaxial layer of 4H-SiC(0001)8°N-/N+ substrate is fabricated. The microstructure and electrical characteristics analysis on the film and Al2O3/SiC interface has shown that Al2O3 deposited has a good bulk characteristics and a good quality between Al2O3 and SiC. The breakdown electrical field of Al2O3 film is 25 MV/cm; the MIS capacitor has a fairly low gate leakage current (current density of 1×10-3A/cm-2 with a electric field of 8 MV/cm) under acceptable interface effective charge (2×1013 cm-2). Current-voltage measurement and analysis has shown that 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 requirement of SiC MISFET devices. Besides this, the gate leakage current is co-influenced by both of Frenkel-Poole mechanism and Schottky emission.