Effect of magnetic field quantization on the shallow acceptor spectrum in strained Ge/GeSi heterostructures

We presents a calculation of acceptor energy states in Ge/GeSi heterostructures in the presence of a magnetic field performed within an effective mass approach. Both spatial quantization and the effect of the strain due to the mismatch between the Ge and GeSi layers have been accounted for. Together with energy states and wavefunctions we have calculated the matrix elements associated with the electromagnetic interaction in the dipole approximation. The results so obtained have provided the basis for a microscopic interpretation of photoresponse spectra as a function of the magnetic field up to 50 kOe, which were measured at 4.2 K. The theory is found to agree satisfactorily with experiments and has enabled us to obtain a close correlation between the photoresponse spectra and the spatial profile of the acceptor concentration inside the heterostructure.