Modified perturbational method for the magnetoexciton ground state in quantum wells.

Abstract

We have developed a modified perturbational approach for the calculation of the heavy-hole exciton ground state in semiconductor quantum-well type-I structures in the presence of a magnetic field applied in the direction parallel to the growth axis. In the envelope-function approximation, ignoring the valence-band-mixing effect, the unperturbed wave function is expressed in terms of subband wave functions in the growth axis and the product of two-dimensional hydrogen and oscillatorlike wave functions for the in-plane component. For the exciton ground state, two variational parameters are used in the unperturbed wave functions to cover an arbitrary strength of the magnetic field in a rigorous manner. A simple relation between the binding energy at the zero field and the diamagnetic shift at low fields is derived in an analytic form. The heavy-hole in-plane mass is considered as an adjustable parameter, and this provided a method for obtaining the heavy-hole in-plane mass from a comparison of the present calculation and experimental results. Calculated results are compared with available experimental data of GaAs/(In,Ga)As strained quantum wells. The magnetic behavior of the heavy-hole exciton ground state is discussed for various growth parameters, such as the well width and indium fraction.