Portal de Periódicos da CAPES

Binding energies of excited shallow acceptor states in GaAs/ Ga 1 − x …

1989; American Physical Society; Volume: 40; Issue: 8 Linguagem: Inglês

10.1103/physrevb.40.5602

1095-3795

Alfredo Pasquarello, Lucio Claudio Andreani, R. Buczko,

Advanced Semiconductor Detectors and Materials

Binding energies of shallow acceptor states in GaAs/${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Al}}_{\mathrm{x}}$As quantum wells are calculated as a function of the well width. The complex valence-band structure is taken into account in a four-band effective-mass theory. The acceptor envelope function is expanded in valence envelope functions in the two-dimensional k space. In this way, the boundary conditions are satisfied by construction. The effect of different dielectric constants in well and barrier materials is taken into account by considering infinite series of image charges. This method of calculation is appropriate for all positions of the acceptor centers, both inside the well and in the barrier, and is particularly suited to evaluate binding energies of excited states. Examples of charge-density distributions of ground and excited states are presented for different positions of the acceptor centers. A first-order perturbation calculation is used to obtain the binding energy of the ground state for on-center acceptors. Theoretical predictions of the transition energies from ground to excited states are found to be in good agreement with available experimental data obtained from far-infrared absorption measurements.