Impurity Properties of Inversion Layers with Electronic and Substrate Quantum Screening

Abstract

In this paper, the combined effect of electronic and substrate screening on impurity states in inversion layers is investigated theoretically. An explicit expression of the screened impurity interaction potential with an effective screening parameter, depending on the material and structural parameters, is established analytically for the first time. The main physical results are (a) an enhancement of the carrier saturation effect and (b) the dependence of the nature of the screening mechanism on the dielectric type (low-κ and high-κ) of the oxide layer. An experimentally measurable impurity binding energy is studied and numerically presented for realistic InSb/SiO2/SiO2/metal (ll-) and InSb/S(sulfur)/HfO2/metal (lh-κ type) multi-layer structures. A substantial enhancement of the binding energy is obtained with the non-degenerate Q2D EG for the ll-κ-type structure, reaching an almost fourfold value of the InSb bulk sample (~0.66 meV).