Doping superlattices in organometallic vapor phase epitaxial InP

Abstract

Doping superlattices (nipi structures) have been grown in InP using organometallic vapor phase epitaxy in an atmospheric pressure reactor using trimethylindium and phosphine in a hydrogen ambient. The n-type and p-type dopants were diethyltellurium and dimethylzinc, respectively. The 4-K photoluminescence spectra at various excitation intensities are presented for a structure consisting of six 200-Å layers with doping levels of 1×1018 and 2×1018 cm−3 for the n and p layers. The luminescence peak is found to occur at energies considerably less than the band gap of InP and to move to higher energies with increased excitation intensity, as expected for doping superlattices where the band gap, which is indirect in real space, increases with increasing excited carrier concentration. The total photoluminescence signal decays in several steps, each exponential, with time constants ranging from 6×10−8 to 7×10−4 s at 4 K, typical of these spatially indirect band-gap materials.