Temperature Dependence of Exciton Linewidths in InSb Quantum Wells

Excitons play a dominant role in the optical properties of semiconductor quantum wells. Their stability, therefore, is important for possible devices exploiting excitons. We studied the linewidths of excitons in InSb/AlInSb quantum wells between 4.2 and 300K using Fourier transform infrared spectroscopy. Even though the exciton binding energy is only about 1 meV, the absorption is excitonic up to room temperature, due to very weak LO-phonon-electron coupling. The electron-phonon coupling constants and exciton binding energies were obtained through fitting the experimental data. We found that acoustic phonon scattering must be taken into account in fitting the experimental exciton linewidths. The observation of excitons in InSb quantum wells also enables us to study other properties of the material system including strain.