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

We describe the photoluminescence spectroscopy (PL) and Fourier transform i nfrared absorbance spectroscopy characterization of a large set of InAs/GaS b type-II strained layer superlattice (SLS) samples. The samples are design ed 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 t hickness is increased, we observe a spectral blue shift of the PL peaks tha t is accompanied by an increase in intensity, narrower linewidths, and a la rge reduction in the temperature sensitivity of the luminescence. These eff ects occur despite a significant reduction in the electron-hole wave functi on overlap as the GaSb layer thickness is increased. In addition, we compar e 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. (C) 2001 American Inst itute of Physics.