Photoluminescence from as-grown and annealed GaN_(0.027)As_(0.863)Sb_(0.11)/GaAs single quantum wells

摘要

We have investigated characteristics of photoluminescence (PL) spectra obtained from as-grown and annealed GaN_(0.027)As_(0.863)Sb_(0.11)/GaAs single quantum wells (SQWs). For the as-grown SQW at low temperature (< 150 K), a broadband emission at ～0.9 eV has been observed in addition to the band-gap-related recombination at ～0.95 eV. After annealing, this broad emission disappears and the band-gap-related PL peak blueshifts ～55 meV. The Stokes shift for this peak is 11 meV at 10 K. Thus, the low-temperature PL peak is mainly associated with the recombination of localized excitons. A rise in temperature leads to a continuous change in this peak; the contribution associated with localized excitons decreases while the contribution associated with free-excitons increases. Above 150 K the line shape gradually loses the Gaussian profile and a high-energy tail appears due to a thermal band filling effect. In this temperature range (> 150 K), the PL peak is attributed to free-carrier recombination.