The origin of optical gain in cubic InGaN grown by molecular beam epitaxy

The optical properties of cubic InGaN samples with varying In content are i nvestigated to provide insight into the processes responsible for optical a mplification. The samples were grown by molecular beam epitaxy on GaAs subs trates. The structural and optical properties were studied by means of time -resolved and time-integrated photoluminescence spectroscopy and cathodolum inescence microscopy, as well as gain measurements at various temperatures. From these measurements, localized states are proposed to be responsible a s recombination mechanism. The cathodoluminescence measurements evidence a direct correlation of the degree of In fluctuation and the efficiency of op tical amplification of the samples. (C) 2000 American Institute of Physics. [S0003-6951(00)04720-3].