5.1 Introduction to III-V Nitrides - Introduction

The most sought after property of III-Nitride semiconductors is their wide direct bandgap, permitting the fabrication of highly efficient optoelectronic devices operating in the blue and ultraviolet part of the spectrum. The wurtzite polytype of GaN, AlN, and InN form a continuous alloy system whose direct bandgaps range from 1.9eV to for InN, to 3.4 eV for GaN, to 6.2 eV for AlN, therefore covering a part of the electromagnetic spectrum that is not covered by conventional semiconductor technology. Current semiconductor technology covers the spectrum from infra-red (IR) to green.

There are many applications for such devices including blue LED's, efficient full color flat panel displays, blue lasers, UV detectors, high temperature sensors, and radiation resistant circuitry for space applications (Ref. 1). Full color flat panel displays with low power consumption are desirable for lab-top computers, whose battery life is severely limited by the displays in use today. Blue lasers with their shorter wavelength will permit higher recording densities of all media based on laser technology, including CD-ROM and magneto-optical (MO) disk drives. UV detectors have a variety of military and civil applications and high temperature sensors are desirable under extreme conditions like inside jet engines.

There are several review papers available concerning III-Nitride growth, their properties and applications. A comprehensive review is given by S. Strite and H. Morkoç in a 1992 paper (Ref. 1). A follow-up review paper (Ref. 8) was published by S. Strite et. al. in 1993. A review on MBE growth of nitride thin films was published in 1993 by M. J. Paisley and R. F. Davis (Ref. 2). A paper reviewing the deposition, characterization, and device development in diamond, silicon carbide, and gallium nitride was published by R. F. Davis in 1992 (Ref. 3).

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