Temperature dependence of exciton life-time in GaAs/ AIGaAs quantum wells

719-722In GaAs/AJGaAs quantum well structures, the confinement of electrons as well as, holes in GaAs well region causes enhancement of Coulomb interaction, which leads to formation of excitons with large binding energy, and, therefore, excitonic states persist even up to room temperature. The phenomenon of photoluminescence (PL) in such structures is dominated by radiative recombination of excitons. The PL and PL decay time is found to depend on temperature. At higher temperatures, thermal population of higher excitonic sub-bands and exciton ionization also need to be considered. The temperature dependence of radiative and non-radiative exciton life-times have been formulated. The nonlinear behaviour of temperature dependence of total life-time of exciton or the PL decay time has been indicated. At low temperatures, exciton decay is mainly due to radiative processes whereas at higher temperatures, it is by non-radiative channels. Therefore, the life-time of exciton, initially, increases with temperature, attains a maximum value and then decreases at high temperatures. The processes different from radiative free exciton recombination also play an important role and possibly, dominate the recombination mechanism as the temperature is raised