CONSEQUENCES OF SPACE DEPENDENCE OF EFFECTIVE-MASS IN HETEROSTRUCTURES

The space dependence of the effective mass in heterostructures might l ead to a strong interdependence of the longitudinal and transverse mot ion in systems with heterointerfaces, such as quantum wells. Such inte rdependence results in additional nonparabolicity of the longitudinal motion in quantum wells. At large energies, comparable to or exceeding the depth of a quantum well, the effective mass changes sign and the longitudinal two-dimensional spectrum terminates at a certain critical value of the longitudinal momentum. The space dependence of the effec tive mass also strongly increases the transmission through a potential barrier for electrons with large incidence angles. These effects shou ld have important consequences for impact ionization and tunneling phe nomena in GaN-based heterostructures. (C) 1998 American Institute of P hysics. [S0021-8979(98)00219-9]