Strain and built-in potential effects on optical properties of wurtzite GaN/AlInN quantum dots

Light emission characteristics of wurtzite (WZ) GaN/Al_xIn_1−xN quantum dots (QDs) with piezoelectric (PZ) and spontaneous (SP) polarizations were investigated as a function of Al content through self-consistent calculations. The spontaneous emission coefficient rapidly increases with decreasing Al content and becomes a maximum at about x = 0.8. This is mainly attributed to the fact that the overlap integral between electron and hole wavefunctions is enhanced owing to the broadened potential shape from strain and built-in potential in the valence band. On the other hand, GaN/Al_xIn_1−xN quantum wells (QWs) shows that the spontaneous emission coefficient becomes a maximum at x = 0.7. Also, the light emission intensity of GaN/Al_xIn_1−xN QDs is shown to be greatly increased by the screening effect, irrespective of Al content in the barrier and the case with x = 0.8 shows the largest screening potential.