Effect of Well Thickness on the Intersubband Optical Absorptions in AlGaN/GaN/AlGaN Quantum Wells

By solving the Schrödinger and Poisson equations self-consistently for AlGaN/GaN QWs, we calculate the intersubband optical absorption coefficients for QWs with various well thicknesses. By increasing the well thickness, the amplitude of the dipole matrix increases slowly. However, the decrease of the energy separation results in the red-shift of the resonant absorption peak and the decrease of the magnitude of the absorption peak. Moreover, when the well thickness decreases to 10 Å, the evident decrease of the overlap between wave functions for the first two subbands leads to the abrupt decrease of the amplitude of the dipole matrix and the absorption peak. These results indicate that the intersubband optical absorption can be greatly modulated by the well thickness, the built-in electric field has an important effect on the intersubband absorption coefficients in III-nitride QWs, and III-nitride QWs are potential candidates for the design and application of intersubband devices.