Electron mobility in Gaussian heavily doped ZnO surface quantum wells

Abstract

We present a theory of the low-temperature mobility of electrons in a Gaussian heavily doped zinc oxide surface quantum well ͑ZnO SFQW͒, taking into account both surface impurity and surface roughness scattering. The theory also includes strong confinement due to spontaneous polarization charges on the surface of ZnO. The electron distribution is found to be shifted closer to the surface for the O-polar face, while far away therefrom for the Zn-polar one. Accordingly, both scatterings are remarkably enhanced in the former case, while reduced in the latter one. Further, high-temperature Coulomb correlation among the charged impurities at a high density in a sample subjected to thermal treatment is proven to significantly reduce scattering by them. Therefore, in such a sample, surface roughness scattering dominates the electron mobility, while for a sample without thermal treatment, both scatterings are important. Our theory provides a good quantitative explanation of the experimental data on electron transport, in particular, the different carrier-density dependences of the mobilities measured in O-polar face ZnO SFQWs prepared in different ways, by bombardment with H 2 + ions and by exposure to He + ions, which has not been explained so far.

Electron distribution in polar heterojunctions within a realistic model

“…As a result, combined roughness (CR) scattering, which is a combination of the effects from interface geometric roughness and polarization roughness, is found to be weakened [23]. Further, the value of the wave function at z L a = − near the interface is smaller, so alloy disorder (AD) scattering is also reduced [24].…”

“…In this paper we study the opposite case where the key scattering mechanisms are quite sensitive thereto [23,24]. Therefore, we examine the confinement effect within the realistic model of finite barrier, based on the modified Fang-Howard wave function [5].…”

A novel approach to the evaluation of the interface roughness scattering form factor in intersubband transitions

“…We will derive a formula in which the IFR scattering form factor is given in terms of quantities that are insensitive to the values of the wave functions at the interface. This form factor will be proper for cases that use approximate wave functions and the finite barrier model with the band bending effect [15,16].…”

Binding energy of hydrogenic impurity states in an inverse parabolic quantum well under static external fields

“…The hydrogenic impurities play a crucial role in the design of nano-structured semiconductor materials, due to the fact that they affect strongly their optical and electronic properties, such that to suit the engineer's needs [3,9,18,[20][21][22][23][24][25][26][27][28]. In addition, their influence can be controlled by the presence of external fields.…”