Radiative Recombination in Semiconductors

Heavily doped n-type single crystals of GaN were grown epitaxially by the vapor phase reaction of GaCl and NH3 on Sapphire substrates. GaN is a direct gap semiconductor with a bandgap of 3.25eV. It fluoresces efficiently in the visible as well as the UV. Single crystals of AlP were prepared by the disproportionation of gaseous AlI in the presence of PH3 either as freely nucleated whiskers or epitaxially on GaAs or Si substrates. Attempts to determine the mechanisms of the efficient Cu green luminescence in ZnS and the mechanism responsible for room temperature lasing in CdS were unsuccessful. In order to design semiconductor alloy systems to achieve high efficiency luminescence in the visible, the authors have observed the effects of alloying small amounts of InP and AlP with GaP on the luminescence of GaP.