Group III-nitrides, and in particular, aluminum nitride (AIN), gallium nitride (GaN), and indium nitride (InN) make up a class of compound semiconductors with direct bandgaps ranging from 1.2 electron volts to 6.2 electron volts (eV). They afford a broad range of applications including light emitting diodes (LED's) and laser diodes (LD's) emitting from the visible to the ultraviolet (UV) portions of the electromagnetic spectrum, radiation detectors, and high power, high frequency electronic devices capable of operating at high temperatures, and in hostile chemical environments. Materials studied in this work were grown on silicon substrates, Si(111) by Molecular Beam Epitaxy (MBE) under a broad range of growth parameters and characterized using X-ray diffraction (XRD), Energy Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), Photoluminescence (PL), and four-point probe resistivity measurements. Growth began with deposition of 0.3 monolayer (ML) of Al on the Si(111)7x7 surface leading to fully passivated Si(111) [root of]3x[root of]3-Al surface. Next, an AIN buffer layer and then the GaN layers were deposited. X-ray measurements indicated growth of single-crystalline hexagonal GaN(001) while PL measurement demonstrated a peak position corresponding to bulk hexagonal-GaN. Sample morphology and resistivity showed a strong dependence on growth conditions. The layer RMS roughness increased with increasing thickness for samples grown with low atomic-nitrogen (N) to molecular N ratio while smoother layers were obtained at the highest atomic N concentrations. Un-intentionally doped layers were n-type. P-type doping was achieved by doping with Mg.

Gallium nitride films have been grown on 6H-SiC substrates employing a new form of selective lateral epitaxy, namely pendeo-epitaxy. This technique forces regrowth to start exclusively on sidewalls of GaN seed structures. Both discrete pendeo-epitaxial microstructures and coalesced single crystal layers of GaN have been achieved. Analysis by SEM and TEM are used to evaluate the morphology of the resulting GaN films. Process routes leading to GaN pendeo-epitaxial growth using silicon substrates have also been achieved and the preliminary results are discussed.

Wide direct band gap gallium nitride (GaN) semiconductor has received significant attention as an ideal material for various applications in the optoelectronic devices. One major use of GaN is the development of energy-efficient solid state light-emitting diodes. Currently, most commercially available GaN semiconductor are produced through advanced deposition techniques which involve sophisticated technologies and are relatively expensive and complicated to setup. As an alternative, the sol-gel spin coating method, which is relatively simpler, cheaper, safer, and more scalable was proposed. In this book, the process route and recipe for producing highly c-oriented crystalline GaN thin films via the sol-gel spin coating approach were described in detail. Some insights into the factors affecting the surface morphology as well as structural and optical properties of the deposited films were presented. Eventually, this book could inspire further studies into the development of low-cost GaN thin films.