Comparison of light emission in InGaN/GaN light-emitting diodes with graded, triangular, and parabolic quantum-well structures

The light emission properties of InGaN/GaN quantum well (QW) light-emitting diodes with non-square layers with graded, triangular, and parabolic shapes are investigated using multiband effective mass theory. These results are compared with those of conventional InGaN/GaN QW structures. The spontaneous emission peak of non-square QW structures is shown to be improved compared to a conventional QW structure. In particular, the parabolic QW structures shows a slightly larger emission peak than the graded or triangular QW structure. This can be explained by the fact that a smaller In composition in the well is needed to give a transition wavelength of 440 nm.