Gadolinium Oxide and Scandium Oxide: Gate Dielectrics for GaN MOSFETs

Abstract

Scandium oxide was deposited epitaxially on (0001) GaN via gas-source molecular beam epitaxy (GSMBE) using elemental Sc and an electron cyclotron resonance (ECR) oxygen plasma. HXRD indicated that the Sc2O3 has a lower defect density than similarly prepared films of Gd2O3. The scandium oxide was atomically smooth, with a rms roughness of 0.5–0.8 nm, and was uniform in stoichiometry as measured by Auger electron spectroscopy (AES) depth profiling. An interface state density of mid 1011 eV—1 cm—2 was determined from capacitance–voltage profiling using the Terman method. This interface state density was roughly a factor of five lower than that obtained from similar diodes made from SiO2 on GaN.