Electronic and Optical Properties of a- and m-Plane Wurtzite InGaN–GaN Quantum Wells

Electronic and optical properties of a-(Phi = 0) and m-plane (Phi = pi/6) InGaN-GaN quantum-well (QW) structures are investigated using the multiband effective-mass theory with an arbitrary crystal orientation. These results are compared with those of c-plane or (0001)-oriented wurtzite InGaN-GaN QWs. We derive explicitly the Hamiltonians with their elements and the interband optical matrix elements with polarization dependence for the a-, m-, and c-planes. The bandgap transition wavelength of the QW structure with the m-plane is found to be longer than that of the QW structures with the a-plane. The average hole effective masses of the topmost valence band along k´_y for the a-and m-planes are significantly lower than that of the c-plane. Here, the prime indicates physical quantities in a general crystal orientation. In addition, their optical gain and optical matrix element show strong in-plane anisotropy. The optical gain of the y´-polarization is much larger than that of the x´-polarization because the optical matrix element for the y´-polarization is larger than that of the x´-polarization.