Carrier lifetime measurements in InAs/GaSb strained layer superlattice structures

Minority carrier lifetime, photoluminescence (PL), and interband absorption in midinfrared range of spectra were measured in InAs/GaSb strained-layer superlattices (SLS) grown by molecular beam epitaxy (MBE) on GaSb substrates. The carrier lifetime was determined by time-resolved PL (TRPL) and from analysis of PL response to sine-wavemodulated excitation. Studies of the PL kinetics in the frequency domain allowed for direct lifetime measurements in SLS structures with an excess carrier concentration level of 3.5×1015 cm-3. The minority carrier lifetime at T = 77 K was obtained from the dependence of the carrier lifetime on excitation power. SLS structures with similar absorption wavelengths but with different InAs and GaSb layer thicknesses and with different amounts of strain were investigated and compared with mercury cadmium telluride (MCT) samples. No apparent trend was seen in structures with different number of interfaces per unit length. All SLS lifetime values measured so far are more than an order of magnitude lower than those of MCT.