III-V nitrides and silicon carbide as optoelectronic materials

Abstract

SiC has emerged as the leading candidate for high temperature and high power device applications due in part to the commercial availability of high quality SiC substrates of ever increasing diameter and quality. These accomplishments are due to advances in chemical vapor deposition (CVD) growth of epitaxial structures paving the way for researchers to easily dope both n- and p-type materials as well as obtaining semi-insulating behavior. The large Si-C bonding energy makes SiC resistant to chemical attack and radiation, and ensures its stability at high temperatures. In addition, SiC has a large bandgap, a large avalanche breakdown field, an excellent thermal conductivity, and a high electron saturation velocity. Due to its above properties, it may replace silicon in high-power, high-voltage switching applications, high-temperature electronics, high-power microwave applications, high-radiation environments, or in some UV optoelectronic devices. Metal semiconductor and metal-oxide-semiconductor transistors (MOSFETs) with outstanding high-temperature performance have already been demonstrated. SiC also forms high-quality native SiO2 on the surface, which makes it suitable for devices e.g. MOSFETs. SiC substrates are suitable for nitride epitaxy due to their relatively close lattice match and high thermal conductivity. This substrate is also currently used as a template for a good fraction of the world production of green, blue, and ultraviolet light-emitting diodes based on nitride semiconductors. With the recent introduction of a controllable 4H polytype that exhibits large electron mobilities, SiC is certain to attract more attention for high-power electronics applications.