Operator ordering of a position-dependent effective-mass Hamiltonian in lattice-matched semiconductor superlattices and quantum wells

The position-dependent effective mass Hamiltonian H=- (h/2)[m(z)](alpha )(Delta) [m(z)](beta )(Delta) [m(z)](alpha )+V(z) with 2(alpha) + (beta) =-1 is applied to the problem of periodic heterostructure with abrupt interfaces and discontinuous mass distribution. In order to determine the most suitable operator ordering, numerical results for interband and intersubband transition energies are compared with experimental data for various GaAs/AlxGa1-xAs superlattices and quantum wells. The ordering- related energy shift as a function of structural parameters (well thickness, barrier thickness and height) is investigated. We find that variation of kinetic energy operator ordering can cause transition energy shift exceeding 40 meV. The model with (alpha) = 0 and (beta) = -1 consistently produces the best fit to experimental results.