Effect of surface nitridation on the growth of GaN films on c-sapphire, Si(111) and Si(100) surfaces

Abstract

Group III-nitrides are the most promising wide bandgap semiconducting materials for high efficiency optoelectronic device applications1,2 that operate very well without aging effects, even with very high dislocation densities. Several other semiconductors such as CdS, CdSe, ZnSe and ZnS are extensively used for short wavelength optoelectronic devices. But, due to their short lifetime and low bond energy, one cannot use these in high temperature and harsh chemical environments which limit the use of devices based on these materials. As compared to other competitive materials, GaN has bond energy of 2.3eV/bond, which is large compared to 1.2eV/bond in the case of ZnSe. The III-nitride semiconductors are well suited for devices operating at high temperatures, high current density, high frequency and in harsh chemical environments unlike the traditional Si and GaAs based semiconducting devices3,4. However, the progress in the development of nitride based optoelectronic devices towards their complete potential is hindered due to lack of native substrates, difficulties in making contacts p-type doping5,6. ZnO, an II-VI wide bandgap semiconductor, is intensively studied in recent years along with III-V materials for blue and UV optoelectronic devices.