Non abrupt III-V quantum wells interface simulation. Part 1: bands profile calculation

This work presents a program, based on the Van de Walle-Martin model solid theory, able to compute the most important physical quantities of any In1-xGayAsyP1-y quaternary epitaxially strained growth on any In(1-z)Ga(z)As(w)P1-(w) hypothetical substrate. The adopted interface-band alignment procedure is extensively described. The effect of strain on several examples of ideal heterostructures characterized by abrupt interfaces is discussed in detail. Furthermore, the problem of a composition gradient spread over some monolayers at the interfaces of III-V quantum wells and superlattices, due to the technological problems in group V switches in the present epitaxial techniques is treated extensively. The interface layers are thus non-intentionally strained on the substrate lattice parameter causing a local change in the bands profile along the growth direction. The differences between an ideal rectangular potential and the real profile are shown. The output files of this program consist in the band profiles for electrons, heavy and light holes, which will be used by the program PLSIMUL (described in a subsequent article) to compute the corresponding quantized levels to be compared with experimental 4 K photoluminescence data.