Optical gain characteristics of non-polar Al-rich AlGaN/AlN quantum well structures

Abstract

Optical properties of non-polar Al-rich AlGaN/AlN quantum well (QW) structures were investigated using the multiband effective-mass theory and non-Markovian optical model with the many-body effect. These results are compared with those of the c-plane, i.e., the (0001)-oriented QW structures. The theoretical PL transition wavelength is found to agree well with the experimental result. The optical gain for the x′-polarization is much larger than that for the y′-polarization because the optical matrix element for the x′-polarization is larger than for the y′-polarization. The x′-direction in the non-poalr plane corresponds to c-axis direction. Also, the optical gain for the x′-polarization is shown to decrease with increasing Al composition. This is mainly attribute to the fact that the optical matrix element is decreased due to the reduction in the electron-hole overlap for QW structures with higher Al contents.