Theoretical calculations of the transition energies of a hydrogenic impurity in GaAs/GaAlAs multi-quantum wells in magnetic fields applied at any angle

Abstract

Calculations are made of the energies of the dominant transition (1s to 2p+1-like) of a hydrogenic donor impurity in a multi-quantum-well (MQW) system subject to a magnetic field applied at an angle theta to the direction of growth of the MQW layers. The model used involves constructing suitable basis states, and then performing a matrix diagonalization procedure. The results are compared to the available experimental data, including the extreme cases of fields perpendicular ( theta =0 degrees ) and parallel ( theta =90 degrees ) to the layers. The results are also found to compare well with the results of existing variational calculations.

Donors bound to X valleys in type-II GaAs–AlAs quantum well structures

“…For narrow AlAs layers ͑less than 55 Å͒ the X x,y valleys are higher in energy than the X z valleys, but for larger AlAs layers the X x,y valleys are lower in energy due the effect of residual lattice-mismatch strain. 2 Theoretical studies on shallow impurities in quantum wells used mainly variational techniques [3][4][5] which have compared successfully with measurements in several experimental situations, [5][6][7] and were concentrated mainly on GaAs-AlGaAs type-I quantum wells. Effects of ⌫ϪX mixing on the binding energies of shallow donors in GaAs-AlAs type-I quantum wells, near to the type-I-to-type-II transition, were studied by Wang et al 8 recently, but otherwise there was little effort for the calculation of binding energies in type-II GaAs-AlAs quantum wells.…”

Binding energies of a hydrogenic impurity and of a Wannier exciton in an arbitrary corner structure

“…A variational approach is an effective method for the study of impurity and exciton states in low-dimensional systems. The impurity and exciton binding energies obtained by the variational theory have been successfully compared with a variety of experimental results obtained by many researchers [2,[6][7][8][9][10][11]. Usually, step structures exist at the interfaces of low-dimensional structures [12,13], and this affects their electronic and optical properties considerably.…”

Quantum well excitons in a high magnetic field

“…In addition to the many variational-type calculations which had been cited in Shi et al [1], alternative theoretical approaches for the related problem of the shallow donor in single quantum well (SQW) and multi-quantum well (MQW) systems have been given. Two of the authors (JLD and CAB) have been involved in a matrix diagonalization procedure developed originally by Dunn and Pearl [5] and extended in Barmby et al [6][7][8][9] for the case of magnetic fields pointing at different angles relative to the QW layers. Another of the authors (BSM) has used analytical methods to study shallow donor impurity states and energy levels in cases of large magnetic fields [10,11].…”