MBE growth of oxides for III-N MOSFETs

摘要

Reproducible fabrication of high performance metal oxide semiconductor field effect transistors (MOSFETs) from compound semiconductors will require both good interfacial electrical characteristics and good thermal stability. While dielectrics such as SiO{sub}2, AlN, and GdGaO{sub}x have demonstrated low to moderate interface state densities, questions remain about their thermal stability and reliability, particularly for use in high power or high temperature wide-bandgap devices. In this paper wewill compare the utility of two potential gate dielectric materials: GdO{sub}x and GaO{sub}x. GdO{sub}x has been found to produce layers with excellent surface morphologies as evidenced by surface roughness of less than 1 nm. Stoichiometric films can beeasily obtained over a range of deposition conditions, though deposition temperatures of 500°C appear to offer the optimum interfacial electrical quality. By contrast GaO{sub}x films are quite rough, polycrystalline and show poor thermal stability.Further they exhibit a range of stoichiometries depending upon deposition temperature, Ga flux and oxygen flux. This paper will describe the relationship between deposition conditions and film characteristics for both materials, and will presentelectrical characterization of capacitors fabricated from GdO{sub}x on Si.