GaN and Related Compounds for Wide Bandgap Applications

Abstract

GaN and related compounds are wide bandgap semiconductor materials with great potential for optoelectronic applications from blue to ultraviolet wavelengths, and high-power, high-temperature devices. GaN can be crystallized in either hexagonal (wurtzite) or cubic (zincblende) structure depending on the substrate symmetry and growth conditions. In certain cases both structures may co-exist because of the small difference in energy of formation. High-quality wurtzitic GaN has been grown successfully on a variety of substrates, in particular on the basal plane of sapphires. However, cubic structures possess in principle superior electronic properties i.e. doping efficiency and high-speed transport and allow easy cleaving, as necessary for devices such as lasers [1], [2]. Although the traditional substrate used for nitride material growth is sapphire, it is consequently desirable to explore the possibility of using substrates such as silicon or GaAs. In addition to allowing cubic material growth, this could lead to reduction of interfacial defects and impurities as well as, integration of GaN with Si or GaAs-based devices.