GaN as a representative of its binary cousins, InN and AlN, and their ternaries along
with the quaternary, is considered one of the most important semiconductors after Si.
It is no wonder that it finds ample applications in lighting and displays of all kinds,
lasers, detectors, and high-power amplifiers. These applications stem from the
excellent optical and electrical properties of nitride semiconductors. The parameters
are imperative in determining the utility and applicability of this class of materials to
devices, as will be made evident in this chapter and throughout the book.
In this chapter, the structural, mechanical, thermal, chemical, electrical, and
optical properties of GaN and its binary cousins as well as the substrates commonly
used for nitride epitaxy are treated in a general sense for quick reference. The detailed
properties associated with electrical and optical parameters and properties are
discussed in chapters dealing with transport and optical processes in GaN and
related alloys. Because GaN is used in the form of a thin film deposited on foreign
substrates, meaning templates other than GaN, a discussion of heteroepitaxial thin
films is of paramount importance. Consequently, the properties of nitride films
intricately depend on substrates, inclusive of the inherent properties such as lattice
constants and thermal expansion coefficients, and on the process-induced characteristics
such as surface preparation and chemical and physical interactions at the
surface. These too are discussed in the book.