Negative-donor centers in semiconductors and quantum wells

The negative-donor centers ${\mathit{D}}^{\mathrm{-}}$ in a magnetic field in semiconductors and quantum wells are studied by an effective-mass model that is solved exactly by a diffusion quantum Monte Carlo method. For ${\mathit{D}}^{\mathrm{-}}$ in bulk GaAs, excellent agreement is found between theory and magneto-optical experiments. For ${\mathrm{D}}^{\mathrm{-}}$ in a 100-Å GaAs/ ${\mathrm{Ga}}_{0.75}$ ${\mathrm{Al}}_{0.25}$As quantum well, a sevenfold increase in binding energy over that of the bulk case is predicted at zero field, and the calculated field-dependent ground-state energy is in good agreement with the interpretation of recent high-field magneto-optical data.