Optoelectronic Properties Of GaN, AlGaN And AlGaN-GaN Quantum Well Heterostructures

The dramatic advances in wide bandgap semiconductors since the mid 1980s have been driven by new developments in growth processes, new requirements for high power and high temperature operation and radiation hardness, and the desire for blue and ultraviolet optoelectronic devices. AlxGal-xN has a direct bandgap (3.4-6.2eV), a large and sharp optical absorption edge, a large radiative recombination coefficient, and is quite hard and stable in chemical environments and at elevated temperatures. Challenges in the continued development of the AlGaN material system are the lack of a native substrate, high n-type camer concentrations in epitaxial films and controlled p-doping. In this paper we describe the optical properties that have been achieved with MOCVD grown AlGaN on sapphire substrates and the diffusion of zinc into these GaN epitaxial layers.