Geometry-induced electron doping in periodic semiconductor nanostructures

TL;DR

This paper explores how nanograting geometry in semiconductor layers induces electron doping without impurities, affecting electron concentration and mobility in various hetero- and homojunction nanostructures.

Contribution

It introduces the concept of geometry-induced doping in multilayer nanostructures and analyzes how layer geometry and material properties influence electron concentration.

Findings

G-doping levels of 10^18-10^19 cm^-3 achieved

High G-doping occurs with small band gap differences

Geometry controls electron concentration in nanostructures

Abstract

Recently, new quantum features have been observed and studied in the area of nanostructured layers. Nanograting on the surface of the thin layer imposes additional boundary conditions on the electron wave function and induces G-doping or geometry doping. G-doping is equivalent to donor doping from the point of view of the increase in electron concentration n. However, there are no ionized impurities. This preserves charge carrier scattering to the intrinsic semiconductor level and increases carrier mobility with respect to the donor-doped layer. G-doping involves electron confinement to the nanograting layer. Here, we investigate the system of multiple nanograting layers forming a series of hetero- or homojunctions. The system includes main and barrier layers. In the case of heterojunctions, both types of layers were G-doped. In the case of homojunctions, main layers were G-doped and barrier layers were donor-doped. In such systems, the dependence of n on layer geometry and material parameters was analysed. Si and GaAs homojunctions and GaAs/AlGaAs, Si/SiGe, GaInP/AlGAs, and InP/InAlAs heterojunctions were studied. G-doping levels of 10^18-10^19 cm^-3 were obtained in homojunctions and type II heterojunctions. High G-doping levels were attained only when the difference between band gap values was low.