Investigation on Transparent, Conductive ZnO:Al Films Deposited by Atomic Layer Deposition Process.

Kai Zhao,Dedong Han,Bin Liu,Jingye Xie,Yudi Zhao,Yi Wang,Junchen Dong

doi:10.3390/nano12010172

Abstract

Transparent electrodes are a core component for transparent electron devices, photoelectric devices, and advanced displays. In this work, we fabricate fully-transparent, highly-conductive Al-doped ZnO (AZO) films using an atomic layer deposition (ALD) system method of repeatedly stacking ZnO and Al2O3 layers. The influences of Al cycle ratio (0, 2, 3, and 4%) on optical property, conductivity, crystallinity, surface morphology, and material components of the AZO films are examined, and current conduction mechanisms of the AZO films are analyzed. We found that Al doping increases electron concentration and optical bandgap width, allowing the AZO films to excellently combine low resistivity with high transmittance. Besides, Al doping induces preferred-growth-orientation transition from (002) to (100), which improves surface property and enhances current conduction across the AZO films. Interestingly, the AZO films with an Al cycle ratio of 3% show preferable film properties. Transparent ZnO thin film transistors (TFTs) with AZO electrodes are fabricated, and the ZnO TFTs exhibit superior transparency and high performance. This work accelerates the practical application of the ALD process in fabricating transparent electrodes.

Highlights

Transparent electrodes combine high transmittance and low resistivity well, making them core components in the fields of photoelectric devices, transparent electron devices, advanced displays, and solar cells [1,2,3]
We demonstrated high-performance, transparent ZnO thin film transistors TFTs, where the ZnO active layer, Al2 O3 gate dielectric, and Al-doped ZnO (AZO) electrodes are all deposited by the atomic layer deposition (ALD) process
For the ALD-deposited AZO electrodes, the device performance of the ZnO TFTs has been significantly improved in this work [21]

Summary

Introduction

Transparent electrodes combine high transmittance and low resistivity well, making them core components in the fields of photoelectric devices, transparent electron devices, advanced displays, and solar cells [1,2,3]. The representative transparent electrodes include transparent conductive oxide (TCO) films, graphene and carbon nanotubes, metal nanowires, metal meshes, and ultrathin metal films [4,5,6]. TCO films are the most widely utilized transparent electrodes due to their flexibility, high uniformity, large-scale fabrication, and the fact that they are a mature technology [7,8]. Typical TCO transparent electrodes are InSnO (ITO) films, which have been commercialized for more than three decades [9]. The development of low-cost TCO films play a role in maintaining the prevalence of them

Methods

Results

Conclusion