CHARACTERIZATION AND ELIMINATION OF SURFACE-DEFECTS IN GAXIN1-XP GROWN BY ORGANOMETALLIC VAPOR-PHASE EPITAXY

In this paper we present a detailed study of the mechanism of formatio n and microstructure of hillock type defects in Ga(x)In1-xP layers gro wn by organometallic vapor phase epitaxy (OMVPE) on GaAs substrates. I t was conclusively shown using a combination of dark field microscopy and microprobe analysis that In-containing particulate contamination i s responsible for the formation of these defects. Cross-sectional tran smission electron microscopy (XTEM) showed that the hillocks consisted of three distinct regions, namely, a base region within the GaAs buff er layer which is believed to be the In-containing particulate, a poly crystalline core region located just above the buffer layer/epitaxial layer interface and a highly twinned region in the Ga(x)In1-xP layer. Cathodoluminescence (CL) studies showed that the hillocks contain a hi gh density of non-radiative recombination centers and act as efficient heterogeneous nucleation sites for dislocations. It was demonstrated that a hot wall vapor etch of the reaction cell using HCl leads to the elimination of the hillocks.