Crystal Orientation Dependent Intersubband Transition in Semipolar AlGaN/GaN Single Quantum Well for Optoelectronic Applications

The optical properties of intersubband transition in a semipolar AlGaN/GaN single quantum well (SQW) are theoretically studied, and the results are compared with polar c-plane and nonpolar m-plane structures. The intersubband transition frequency, dipole matrix elements, and absorption spectra are calculated for SQW on different semipolar planes. It is found that SQW on a certain group of semipolar planes (55° < θ < 90° tilted from c-plane) exhibits low transition frequency and long wavelength response with high absorption quantum efficiency, which is attributed to the weak polarization-related effects. Furthermore, these semipolar SQWs show tunable transition frequency and absorption wavelength with different quantum well thicknesses, and stable device performance can be achieved with changing barrier thickness and Al compositions. All the results indicate that the semipolar AlGaN/GaN quantum wells are promising candidate for the design and fabrication of high performance low frequency and long wavelength optoelectronic devices.