Electrical Transport Properties in ZnO Bulk, c/ZnO and ZnMgO/ZnO/ZnMgO Heterostructures

TL;DR

This study analyzes electrical transport in ZnO and related heterostructures, identifying key scattering mechanisms and factors influencing electron mobility, with implications for improving device performance.

Contribution

It provides a detailed quantitative analysis of scattering parameters and mobility enhancement factors in ZnO heterostructures, including correction methods for interface effects.

Findings

Dislocation density reduction improves electron mobility.

Hopping conduction dominates below 50K in ZnO.

Enhanced mobility linked to better electron confinement and interface quality.

Abstract

In this paper, the reported experimental data in [Sci. Rep., 2012, 2, 533] related to electrical transport properties in bulk ZnO, ZnMgO/ZnO, and ZnMgO/ZnO/ZnMgO single and double heterostructures were analyzed quantitatively and the most important scattering parameters for controlling electron concentration and electron mobility were obtained. Treatment of intrinsic mechanisms included polar-optical phonon scattering, piezoelectric scattering and acoustic deformation potential scattering. For extrinsic mechanisms, ionized impurity, dislocation scattering, and strain-induced fields were included. For bulk ZnO, the reported experimental data were corrected for removing the effects of a degenerate layer at the ZnO/sapphire interface via a two layer Hall effect model. Also, donor density, acceptor density and donor activation energy were determined via the charge balance equation. This sample exhibited hopping conduction below 50K and dislocation scattering closely controlled electron mobility closely. The obtained results indicated that the enhancement of electron mobility in double sample, compared with the single one, can be attributed to the reduction of dislocation density, two dimensional impurity density in the potential well due to background impurities, and/or interface charge and strain-induced fields, which can be related to better electron confinement in the channel and enhancement in the sheet carrier concentration of 2DEG in this sample.