MICROCAVITY EFFECTS IN GAN EPITAXIAL-FILMS AND IN AG GAN/SAPPHIRE STRUCTURES/

Luminescence spectra of GaN epitaxial layers grown on sapphire display a strong intensity modulation of the below-band gap transitions and o n the low-energy side of the near-band gap transition. The intensity m odulation is attributed to a microcavity formed by the semiconductor-a ir and semiconductor-substrate interface. The microcavity effect is en hanced by using metallic reflectors which increase the cavity finesse. It is shown that microcavity effects can be used to determine the ref ractive index of the microcavity active material. Using this method, t he GaN refractive index is determined and expressed analytically by a Sellmeir fit. (C) 1997 American Institute of Physics.