Optical properties of GaN layers grown by MOCVD

Abstract

The interband transitions in thin epitaxial films grown by metalorganic chemical vapour deposition (MOCVD) have been studied as a function of temperature (1 0-300K) by photoluminescence (PL) and reflectance measurements. In photoluminescence at low temperature bound and free excitons are observed. Temperature dependence of free exciton energies have been studied in reflectance measurement. In the reflectance spectra excitonic interband transitions f9V.4'7C (exciton FX(A)), f7V (upper band)JT7C (exciton FX(B)) and F7"(lower band)I7C (exciton FX(C)) were observed. From temperature dependence of the excitonic spectra the energy gap dependence is determined using both the Varshni E(T)=E(O)-aT2/(T0+T) and Bosse-Einstein E(T)=E(O)-A/[exp(3/T)-1] expressions.