Large Optical Gain Characteristics of Tensile-strained 440-nm InGaN/AlInN Quantum Well Structures

The optical gain characteristics of tensile-strained InGaN/AlInN QW structures are investigated as a function of the In composition in the well by using the non-Markovian gain model with many-body effects. The internal field decreases with increasing In composition in the well and becomes zero at some critical In compositions. The optical gain decreases with increasing In composition when the In composition exceeds 0.08 for the InGaN/Al0.6In0.4N QW structure because the quasi-Fermi level separation decreases with increasing In composition. The optical gain peak of the InGaN/AlInN QW structure with a transition wavelength of 440 nm is shown to be much larger than that of the conventional 440-nm InGaN/GaN QW structure. This can be explained by the fact that the matrix element for the InGaN/AlInN QW structure is much larger than that for the InGaN/GaN QW structure due to a reduction in the internal field.