Stacking fault-associated polarised surface-emitted photoluminescence from zincblende InGaN/GaN quantum wells
A photoluminescence (PL) study was performed on zincblende-InGaN/GaN quantum wells. These structures contained a high density of stacking faults, which cause the segregation of indium at the intersection with the quantum wells, creating quantum wires. Emission from these quantum wires dominates the room temperature PL spectra and is highly polarised (Fig 1): emission from the quantum wells is additionally observed at 10K (Fig 2). The 10K PL decays show that the emission from the quantum wells is fast and mono-exponential, and the quantum wire emission is a stretched exponential (Fig 3). 10K PL-excitation measurements show absorption into the GaN barriers, which does not shift with emission energy. Absorption into the quantum well is observed and does not shift with emission energy over the quantum wire emission (Fig 5). Low temperature PL spectra show emission from the quantum wells and wires (Fig S1). As the temperature is increased, the quantum well emission quenches at a faster rate than the wire emission and the peaks redshift (Fig. S2). As the excitation power is increased, there is no change in the PL spectra (Fig S3). Changing the polarisation of the excitation has no effect on the PL or PL-excitation spectra (Fig S4). Simple calculations were performed to calculate the band profile and carrier ground states in quantum wire structures (Fig S5). An estimation of the ground and excitated hole state energies was also calculated (Fig S6). This allowed a calculation of the change in the degree of linear polarisation of the quantum wire emission at 300K, compared with 10K (Fig S7).