EMERGING GALLIUM NITRIDE BASED DEVICES

Wide bandgap Gall has long been sought for its applications to blue an d UV emitters and high temperature/high power electronic devices. Rece nt introduction of commercial blue and blue-green LED's have led to a plethora of activity in all three continents into the heterostructures based on GaN and its alloys with AlN and InN. In this review, the sta tus and future prospects of emerging wide bandgap gallium nitride semi conductor devices ape discussed. Recent successes in p-doping of GaN a nd its alloys with InN and AlN, and in n-doping with much reduced back ground concentrations have paved the way for the design, fabrication, and characterization of devices such as MESFET's, MISFET's, HBT's, LED 's, and optically pumped lasers. We discuss the electrical properties of these devices and their drawbacks followed by future prospects. Aft er a short elucidation of materials characteristics of the nitrides, w e explore their electrical transport properties in detail. Recent prog ress in processing such as formation of low-resistance ohmic contacts and etching is also presented. The promising features of quartenaries and double heterostructures in relation to possible current injection lasers, LED's, and photodetectors are also elaborated on.