Effect of faceting on the band gap of ordered GaInP

Abstract

It has been shown that under certain growth conditions the pseudobinary semiconductor alloy GaInP shows cation site ordering into the Cu-Pt structure, and that this ordering results in a lowering of the band gap Eg from that of the disordered alloy. The Eg lowering is known to depend on growth conditions, including the orientation of the substrate. We study the dependence of Eg on epilayer thickness for GaInP grown by metal-organic vapor-phase epitaxy. For epilayers grown on singular (100) substrates under growth conditions conventionally used to produce ordered material, Eg decreases dramatically with increasing epilayer thickness: Eg for a 10-μm-thick epilayer is ∼40 meV lower than for a 1-μm-thick epilayer. This dependence of Eg on thickness can be understood in terms of the recently observed faceting of the GaInP growth surface.