Anomalous Temperature Dependence of Photoluminescence in GaInNAs/GaAs Multiple Quantum Wells

Photoluminescence (PL) spectra of GaInNAs/GaAs multiple quantum wells (MQWs) grown on a GaAs substrate by molecular beam epitaxy are measured in a range of temperature and excitation power densities. The energy position of dominant PL peak shows an anomalous S-shape temperature dependence instead of the Varshni relation. By the careful inspection, especially for the PL under lower excitation power density, two near band-edge peaks are well identified. They are assigned to carriers localized in nitrogen-induced bound states and interband excitonic recombinations respectively. It is suggested that the temperature-induced switch of such two luminescence peaks in relative intensity causes a significant mechanism responsible for the S-shape shift observed in GaInNAs. A quantitative model based on the thermal depopulation of carriers is used to explain the temperature dependence of the PL peak related to N-induced bound states.