Chapter 1 - Introduction

Abstract

Wide bandgap III-nitrides—including (AI,Ga,In)-N—have seen enormous success in their development especially, in the latest stages of 20th century. Many substantial problems had to be overcome before these materials could constitute useful devices. High density of dislocations because of the lack of lattice-matched substrates and low doping efficiency were the most challenging problems that researchers in this area had to face. Today blue/violet light-emitting diodes and laser diodes based on (Al,In,Ga)-N have been successfully commercialized. Blue/green light emitting diodes (LEDs) have already found their market in full-color liquid crystal displays (LCDs) and traffic lights. The unique properties of III-nitrides lead to a range of applications from optoelectronic devices to high-power electronics. The wide bandgap of gallium nitride (GaN) makes this material suitable not only for light emitting source but also for high-temperature applications. GaN and its alloys have the potential for forming high power electronics such as transistors or thyristors. Ultraviolet solar-blind photodetectors based on AlGaN have applications in early missile threat detection and interception, chemical and biological threat detection, UV flame monitoring, and UV environmental monitoring. There are some other conceivable applications for III-nitrides such as surface acoustic wave generation, acousto-optic modulator, and devices that utilize negative electron affinity.