Photoreflectance and photoluminescence study of Ga 0.76 In 0.24 Sb / GaSb single quantum wells: Band structure and thermal quenchingof photoluminescence

Photoreflectance (PR) and photoluminescence (PL) have been applied to study the band structure and PL thermal quenching for Ga 0.24 In 0.76 Sb / GaSb quantum wells (QWs) of the widths varying from 10 to 21 nm. In the case of PR spectra, a strong GaSb-related resonance followed by Franz-Keldysh oscillations and PR resonances associated with optical transitions between the QW ground and the excited states have been clearly observed. The QW transitions have been identified on the basis of theoretical calculations which were performed in the framework of the effective mass model. Satisfactory agreement between theoretical calculations and experimental data has been found for the conduction band offset of ∼ 80 % - 85 % that is consistent with the theoretical predictions, which were obtained within the "model-solid" theory. In the case of PL measurements, a very efficient QW emission without any localization features has been observed in the temperature range of 10-280 K. It has been concluded that the thermal quenching of PL can be described by a standard expression with two characteristic activation energies, which can be attributed to an electron escape and a heavy-hole escape to the conduction and valence continua in GaSb barriers, respectively. The obtained activation energies are in the range of 20-30 and 80-100 meV for the first and the second quenching mechanism, respectively. The Varshni parameters for the QW ground state transition have been determined to be α = 0.36 - 0.39 meV / K and β = 155 - 175 K .