Cathodoluminescence of Ga_(1-x)In_xAs_ySb_(1-y) epitaxial layers

Abstract

Quaternary Ga_(1-x)In_xAs_ySb_(1-y) layers lattice matched to a GaSb substrate are of interest for applications in the infrared range. In this work, the luminescence of Ga_(1-x)In_xAs_ySb_(1-y) layers grown on GaSb by metal organic vapor phase epitaxy (MOVPE) with different In and As contents, has been studied by cathodoluminescence (CL) in a scanning electron microscope (SEM). CL images show a cellular structure which indicates the presence of dislocations decorated by recombination centers. Band gap values of 0.735 eV and 0.717 eV were measured from the CL spectra of two samples with diferent In content. This result is analyzed in the frame of existing theoretical models relating band gap with In and As content, in quaternary lattice matched layers. The band gap values are in good agreement with results of atomistic pseudopotential calculations.