Probing the wave function of quantum confined states by resonant magnetotunneling

We have measured the low-temperature (4.2 K) current-voltage characteristics I(V) of a GaAs/(AlGa)As double-barrier resonant tunneling diode in which the quantum well is intentionally δ doped with Si donors. A peak in I(V) at low voltage is observed and attributed to resonant tunneling of electrons from two-dimensional free-electron-like states into the fully localized bound states of the shallow donors. The magnetic-field dependence of this peak is fundamentally different from that of the main resonance. We show that the Fourier spectrum of the shallow-donor wave function may be deduced from the variation of the peak amplitude with magnetic field.