Pressure dependence of infrared photoluminescence spectra from HgTe/CdTe superlattices

Abstract

The authors have investigated the pressure dependence of the infrared photoluminescence (PL) of HgTe/CdTe superlattices (SLS) at liquid nitrogen temperature up to 30 kbar. They observed several PL peaks with energies ranging from approximately 130 meV to approximately 700 meV. The most prominent peak at approximately 130 meV, which has been attributed to the recombination across the SL bandgap, moves higher in energy with a pressure coefficient of <or approximately=1 meV kbar-1. Other peaks at higher energies have similar pressure coefficients of 0-2 meV kbar-1. A calculation based on the envelope-function approximation gives a pressure coefficient of at least approximately 6.5 meV kbar-1, which is far outside the error bars of the measured pressure dependence of the main peak, <or approximately=1 meV kbar-1. Possible explanations, including a modification of the current model of HgTe/CdTe SL bands and a reinterpretation of the PL peaks, are examined.