Interface simulation of strained and non-abrupt III–V quantum wells. Part 2: energy level calculation versus experimental data

Abstract

This work describes a program able to compute the allowed energy levels and the respective wavefunctions of strained In 1 − x Ga x As y P 1 − y In 1 − z Ga z As w P 1 − w for electrons, light and heavy holes in single- and multi-quantum wells and superlattices. Ground and excited states can be detected. The problem of non-abrupt interfaces has been taken into account. The computation on intentionally strained QW structures can be performed. The simulation of coupled wells may also be done, allowing theoretical prediction on the 4 K photoluminescence emission of superlattices. The adopted mathematical approach has been treated in details. The results of the presented simulations performed on heterostructures grown by low-pressure metallorganic vapor phase epitaxy and by chemical beam epitaxy heterostructures are compared with 4 K Fourier transform photoluminescence and with room temperature IR absorption data. The data used as input by this program are previously computed by the program BANDSTRAIN (described in a previous paper). In this work also the simulation of high resolution X-ray diffraction patterns is briefly presented and compared with the experimental curves; it is shown how the combined simulations of PL and X-ray data is a powerful tool in the interfaces characterization. Finally, qualitative information is extracted from high-resolution transmission electron microscopy micrographs.