Although Metal-Organic Chemical Vapour Deposition (MOCVD) is the most common technique to grow III-nitride films for light-emitting diode (LED) application, there are still several open questions such as the dislocations in LED structures and low thermal conductivity. The solutions to such problems have been approached by various deposition techniques over the past few years. In this review, the properties of gallium nitride (GaN) grown using different techniques and the consequences of the heteroepitaxial layers are discussed. At first, the general properties of GaN and its application for optoelectronic devices are presented briefly. To improve the crystallinity of GaN, it is necessary to identify and evaluate the defects present in the heteroepitaxial layers, which lead to poor crystal quality of films, and eventually to find an approach to overcome these issues. Several approaches using various substrates that have been published are discussed here and, finally, the directions of a new potential method for GaN growth using the magnetron sputtering technique are described.
