Wurtzite-Structure Materials (Group-III Nitrides, ZnO)

Abstract

The success in growing high-quality wide-band-gap group-III-nitride alloys over the past several years has led to immense effort in nitride-based semiconductor device research. In particular, the achievement of controlled p- and n-type doping of respective device constituents resulted in the development of short-wavelength light-emitting diodes, laser diodes, and high-temperature, high-power, high-frequency electronic devices [1, 2, 3, 4, 5, 6, 7] Studies of fundamental physical properties of novel materials is essential for designing new device structures. Device heterostructures may consist of numerous layers of compound materials with different compositions. Metrology and control of individual layer properties - such as the free-charge-carrier concentration and mobility, as well as strain and composition - represent a challenge. The previous sections have demonstrated the applicability of (generalized) infrared ellipsometry for characterization of free-charge-carrier properties, ordering, strain, and alloying effects in arsenide- and phosphide-based semiconductor compound materials. This section focuses on the intricate infrared-polarization response of the optically anisotropic wurtzite III-nitrides and their complex device heterostructures. The infrared ellipsometry approach tackles this phenomenon, and its future perspective may be envisioned as nondestructive and noninvasive optical metrology tool for semiconductor research and production environments.