Band alignment at a ZnO/GaN (0001) heterointerface

Abstract

We report the experimental results of the valence band offset at a ZnO/GaN (0001) heterointerface. The ZnO/GaN (0001) heterointerface is prepared by growing a ZnO layer on (0001) GaN/Al2O3, in which the ZnO layer is epitaxially deposited by plasma-assisted molecular-beam epitaxy, while the GaN template is prepared by metalorganic chemical-vapor deposition. Ex situ ultraviolet and x-ray photoelectron spectroscopy have been used to measure the valence band offset ΔEV. The photoelectron spectroscopy measurements are done before and after Ar+ ion cleaning of the surfaces. Type-II band alignments with band offsets of ΔEV=1.0 eV (before cleaning) and 0.8 eV (after cleaning) with the valence band maximum of GaN being placed above that of ZnO are obtained.

Depth-resolved cathodoluminescence study of zinc oxide nanorods catalytically grown on p-type 4H-SiC

“…In optoelectronics ZnO possesses potential for various applications such as light-emitting diodes and lasers [3,4]. However the stable and reproducible p-type doping in ZnO is still a problem, which is hindering the realization of a ZnO p-n homo-junction diode [5]. The hetero-junction devices often show less efficiency than homo-junction devices because an energy barrier is created at the junction, which decreases carriers injection efficiency.…”

The band alignment of Cu2O/ZnO and Cu2O/GaN heterostructures

“…Robertson and Clark 11 used local density approximation (LDA) with a screened exchange hybrid density functional. As can be seen from Table II), which are to be compared to the theoretical and experimental data of Robertson and Clark, 11 Hong et al, 19 and Liu et al 20 Hong et al gave two values, before and after cleaning (value in brackets) with Ar + -ion irradiation of the surfaces, while Liu et al investigated the influence of polar and non-polar (values in brackets in Table II) surfaces on the CBO and VBO.…”

Hybrid density functional study of band alignment in ZnO–GaN and ZnO–(Ga1−xZnx)(N1−xOx)–GaN heterostructures

“…For example, Hong et al measured the valence band offset (∆E VBO ) at a ZnO/GaN (0001) heterointerface by means of ex situ ultraviolet and x-ray photoemission spectroscopy (UPS/XPS). The ∆E VBO was estimated to be 0.8 eV -1.0 eV in their work 10 . Veal et al evaluated the ∆E VBO of ZnO/GaN heterojunctions using the transitivity rule of the natural band offsets between III-V compounds and II-IV compounds.…”

“…Considerable efforts have been made to determine this parameter both experimentally [10][11][12] and theoretically. [13][14][15] However, these works gave quite different values.…”