Written by recognized leaders in this dynamic and rapidly expanding field, Indium Nitride and Related Alloys provides a clear and comprehensive summary of the present state of knowledge in indium nitride (InN) research. It elucidates and clarifies the often confusing and contradictory scientific literature to provide valuable and rigorous insight into the structural, optical, and electronic properties of this quickly emerging semiconductor material and its related alloys. Drawing from both theoretical and experimental perspectives, it provides a thorough review of all data since 2001 when the band gap of InN was identified as 0.7 eV. The superior transport and optical properties of InN and its alloys offer tremendous potential for a wide range of device applications, including high-efficiency solar cells and chemical sensors. Indeed, the now established narrow band gap nature of InN means that the InGaN alloys cover the entire solar spectrum and InAlN alloys span from the infrared to the ultraviolet. However, with unsolved problems including high free electron density, difficulty in characterizing p-type doping, and the lack of a lattice-matched substrate, indium nitride remains perhaps the least understood III-V semiconductor. Covering the epitaxial growth, experimental characterization, theoretical understanding, and device potential of this semiconductor and its alloys, this book is essential reading for both established researchers and those new to the field.

Described in this thesis is an investigation of some fundamental physical properties of both zincblende and wurtzite Group III - Nitride wide bandgap semiconductor materials. All of the thin films studied were grown by plasma-enhanced molecular beam epitaxy on either GaAs and SiC substrates. This growth method proved to be suitable for nitride expitaxial growth although compromises between the plasma power and the crystal growth rate had to be sought. The zincblende polytypes of GaN and InN were studied with the intent of evaluating their potential as a wide bandgap semiconductor system for short wavelength optical devices. The metastability of these crystals has led us to the conclusion that the zincblende nitrides are not a promising candidate for these applications due to their tendency to nucleate wurtzite domains. Bulk samples of zincblende GaN and InN and wurtzite GaN, AlN and InN were studied by x-ray photoemission spectroscopy (XPS) in an effort to determine their valence band structure. We report the various energies of the valence band density of states maxima as well as the ionicity gaps of each material. Wurtzite GaN/AlN and InN/AlN heterostructures were also investigated by XPS in order to estimate the valence band discontinuities of these heterojunctions. We measured valence band discontinuities of $Delta$E$rmsbsp{v}{GaN/AlN}$ = 0.4 $pm$ 0.4 eV and $Delta$E$rmsbsp{v}{InN/AlN}$ = 1.1 $pm$ 0.4 eV. Our results indicate that both systems have heterojunction band lineups fundamentally suitable for common optical device applications.

The optical properties of wurtzite InN grown on sapphire substrates by molecular-beam epitaxy have been characterized by optical absorption, photoluminescence, and photomodulated reflectance techniques. All these three characterization techniques show an energy gap for InN between 0.7 and 0.8 eV, much lower than the commonly accepted value of 1.9 eV. The photoluminescence peak energy is found to be sensitive to the free electron concentration of the sample. The peak energy exhibits a very weak hydrostatic pressure dependence and a small, anomalous blueshift with increasing temperature. The bandgap energies of In-rich InGaN alloys were found to be consistent with the narrow gap of InN. The bandgap bowing parameter was determined to be 1.43 eV in InGaN.