The growth of gallium nitride and indium nitride by molecular beam epitaxy

The III-nitride conductors are promising materials for the application to optoelectronic devices. They span a range of direct band gaps from 1.9 to 6.2eV at room temperature. The issues relating to the growth of two important semiconductor compounds, GaN and InN, by Molecular Beam Epitaxy (MBE) are studied. A large variety of discrepancies exist between literatures concerning the growth of III-nitrides. Effort has been exercised in this study in order to clarify the ambiguities by providing precise description and calibration of experimental conditions such as substrate temperature, gallium and nitrogen fluxes. Such critical parameters for the growth were largely not reported, or estimated without verifiable calibration procedures. In contrast to GaN, the growth of InN, which has presented a much more difficult problem than for GaN, has not received much attention, largely because of the difficulty of growth. The difficulties encountered during the MBE growth of InN will be addressed by presenting experimental data. Experiments utilizing Reflection High Energy Electron Diffraction (RHEED) and Quadrupole Mass Analyzer (QMA) have been designed to explore the growth front and the decomposition of InN respectively. Interesting RHEED evolution and dissociation phenomena observed in these experiments will be discussed. The improvement of the film quality based on the information obtained from these designed experiments will be demonstrated by using various characterization techniques. At the same time, theoretical growth models based on thermodynamics are reviewed. The theoretical predictions are compared to the experimental data and the discrepancies between them will be discussed in detail.