Spectral blueshift and improved luminescent properties with increasing GaSb layer thickness in InAs–GaSb type-II superlattices

Abstract

We describe the photoluminescencespectroscopy(PL) and Fourier transform infrared absorbance spectroscopy characterization of a large set of InAs/GaSb type-II strained layer superlattice (SLS) samples. The samples are designed to probe the effect of GaSb layer thickness on the optical properties of the SLS, while the InAs-layer thickness is held fixed. As the GaSb layer thickness is increased, we observe a spectralblue shift of the PL peaks that is accompanied by an increase in intensity, narrower linewidths, and a large reduction in the temperature sensitivity of the luminescence. These effects occur despite a significant reduction in the electron-hole wave function overlap as the GaSb layer thickness is increased. In addition, we compare the results of empirical pseudopotential model (EPM) calculations to the observed blueshift of the primary band gap. The EPM calculations are found to be in very good agreement with the observed data.