Pseudopotential methods for superlattices: Applications to mid-infrared semiconductor lasers

Many mid-infrared semiconductor laser sources are now being developed with superlattice active regions. Calculations of gain, index of refraction, and intervalence subband absorption for these laser materials require accurate subband energies, wave functions, and radiative matrix elements. We have r ecently begun using a solution method based on the empirical pseudopotentia l method (EPM). This method shows particular strength in analyzing structur es with short periods or thin layers, for which the standard method, based on k . p perturbation theory and the envelope function approximation, may b e problematical. We will describe the EPM applied to bulk solids and then d emonstrate our direct generalization of the method for applications to supe rlattice structures. Calculations for recently developed mid-infrared semic onductor lasers using type-II superlattice active regions will be used to i llustrate the method. (C) 1999 American Institute of Physics. [S0021-8979(9 9)07515-5].