Phonon ionization of neutral donors in lightly doped GaAs: A model for the conductance oscillations in semiconductor-insulator-semiconductor tunnel structures

A model of space-charge generation by phonon ionization of neutral donors in the n-type GaAs layer of the Hickmott tunnel device is presented. Various features associated with the periodic structures in the junction conductance, such as peak narrowing in magnetic fields attributed to magnetoimpurity resonance, are explained in terms of one-dimensional LO-phonon emission and ionization rate. The high-temperature data in the experiment of Lu, Tsui, and Cox on In-InP contacts is interpreted in terms of carrier capture by ionized impurities with LO-phonon emission, which is the inverse mechanism of LO-phonon ionization. Theoretical results compare well with the experiment.