Confinement-dependent exciton binding energy in wurtzite GaN/Al_xIn_(1−x)N quantum dots

摘要

Exciton binding energies for wurtzite (WZ) GaN/Al_xIn_(1−x)N quantum dots (QDs) with piezoelectric (PZ) and spontaneous (SP) polarizations were investigated by using an effective mass theory. The exciton binding energy gradually decreases with increasing Al content x in the barrier. This can be explained by the fact that the wave functions spreads into the barrier region with decreasing Al content and a higher dimensional character of the exciton is restored. The exciton binding energies for the case with PZ and SP polarizations appears to be much smaller than that for the flat-band model without the built-in field due to PZ and SP polarizations. However, their difference is observed to be negligible due to reduction in carrier confinement for the case with a relatively low Al content (x = 0.7).