Electrical and optical properties of Al-doped ZnO and ZnAl2O4 films prepared by atomic layer deposition

Qiongqiong Hou,Fanjie Meng,Jiaming Sun

doi:10.1186/1556-276x-8-144

Abstract

ZnO/Al2O3 multilayers were prepared by alternating atomic layer deposition (ALD) at 150°C using diethylzinc, trimethylaluminum, and water. The growth process, crystallinity, and electrical and optical properties of the multilayers were studied with a variety of the cycle ratios of ZnO and Al2O3 sublayers. Transparent conductive Al-doped ZnO films were prepared with the minimum resistivity of 2.4 × 10−3 Ω·cm at a low Al doping concentration of 2.26%. Photoluminescence spectroscopy in conjunction with X-ray diffraction analysis revealed that the thickness of ZnO sublayers plays an important role on the priority for selective crystallization of ZnAl2O4 and ZnO phases during high-temperature annealing ZnO/Al2O3 multilayers. It was found that pure ZnAl2O4 film was synthesized by annealing the specific composite film containing alternative monocycle of ZnO and Al2O3 sublayers, which could only be deposited precisely by utilizing ALD technology.

Highlights

In the ZnO-Al2O3 composite material system, Al-doped zinc oxide (AZO) and zinc aluminate (ZnAl2O4) spinels are well known for their applications in optoelectronic devices and chemical industry
The ultraviolet (UV) peak at around 387 nm is from the near-band-edge emission of crystalline ZnO, while the broad peak around 600 nm can be ascribed to the radiative recombination at the defects in ZnO films
AZO and ZnAl2O4 films were prepared by alternating atomic layer deposition (ALD) of ZnO/Al2O3 laminates using DEZn, TMA and water

Summary

Introduction

In the ZnO-Al2O3 composite material system, Al-doped zinc oxide (AZO) and zinc aluminate (ZnAl2O4) spinels are well known for their applications in optoelectronic devices and chemical industry. AZO was considered as an alternative low-cost transparent conductive oxide material instead of indium tin oxide in photovoltaic cells and displays [1,2]. AZO and ZnAl2O4 thin films have been deposited by different techniques [7], such as sol–gel coating [8], pulsed laser deposition [9], chemical vapor deposition [10], radio-frequency sputtering [11], and atomic layer deposition (ALD) [12,13]. ALD technology has been employed to grow transparent conductive AZO films with low resistivity in the order of 10−3 Ω·cm [14,15].

Methods

Results

Conclusion