Binding and transition energies of off-center ${\mathit{D}}^{\mathrm{-}}$ impurity states in quantum wells and magnetic fields

The binding and transition energies of ${\mathit{D}}^0$ and ${\mathit{D}}^{\mathrm{-}}$ off center in GaAs-${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Al}}_{\mathit{x}}$As quantum wells (QW’s) in a magnetic field are reported. It is found that a magnetic field can make the binding energy of ${\mathit{D}}^{\mathrm{-}}$ off center in QW’s not only increase but also decrease and a very strong magnetic field can dissociate a ${\mathit{D}}^{\mathrm{-}}$ into an electron and a ${\mathit{D}}^0$. On the basis of analysis of the variation of ${\mathit{D}}^0$ and ${\mathit{D}}^{\mathrm{-}}$ transition energies with magnetic field, a method is proposed for experimentalists to confirm the ${\mathit{D}}^{\mathrm{-}}$ states in QW’s.