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 sig nificantly 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.