Optical properties of InP doping superlattices grown by metal organic chemical vapor deposition

Abstract

Recently we have reported the first InP superlattice grown by the organometallic vapor phase epitaxy (organometallic vapor phase epitaxy or metal organic chemical vapor deposition) technique. These samples were grown in an atmospheric pressure reactor using trimethylindium and phosphine in a hydrogen ambient. The n- and p-type dopants were diethyltellurium and dimethylzinc, respectively. Several experiments indicate that the interfaces between the n and p regions in these structures are sharp and of high quality. The peak energy and the line shape of the photoluminescence spectra depend on the excitation intensity just as predicted theoretically. In addition, the time decay of the luminescence contains distinct steps, indicating the existence of subbands due to quantum size effects. The first photoreflectance (PR) measurements have also been performed on these doping superlattices. These measurements show that the photoexcited carriers modulate the subband levels in a very predictable fashion. The observed PR line shapes are well explained by photomodulation of the subbands in the conduction band. These line shapes have been fit accurately with a simple model, which accounts for the dependence of the spectrum on the power of the exciting light and on the layer thickness. The agreement between the model calculations, which assume a parabolic well to describe the quantized subbands of the electrons, and the experimental line positions suggests that the interfaces are sharp and that the compensated regions between n and p layers are narrow.