ZnOTe Compounds Grown by DC-Magnetron Co-Sputtering

Olga Sánchez,Manuel Hernández-Vélez

doi:10.3390/coatings11050570

Abstract

ZnOTe compounds were grown by DC magnetron cosputtering from pure Tellurium (Te) and Zinc (Zn) cathodes in O2/Ar atmosphere. The applied power on the Zn target was constant equal to 100 W, while the one applied on the Te target took two values, i.e., 5 W and 10 W. Thus, two sample series were obtained in which the variable parameter was the distance from the Te targets to the substrate. Sample compositions were determined by Rutherford Backscattering Spectroscopy (RBS) experiments. Structural analysis was done using X-Ray diffraction (XRD) spectrometry and the growth of the hexagonal w-ZnO phase was identified in the XRD spectra. RBS results showed high bulk homogeneity of the samples forming ZnOTe alloys, with variable Te molar fraction (MF) ranging from 0.48–0.6% and from 1.9–3.1% for the sample series obtained at 5 W and 10 W, respectively. The results reflect great differences between the two sample series, particularly from the structural and optical point of view. These experiments point to the possibility of Te doping ZnO with the permanence of intrinsic defects, as well as the possibility of the formation of other Te solid phases when its content increases. The results and appreciable variations in the band gap transitions were detected from Photoluminescence (PL) measurements.

Highlights

Zinc Oxide (ZnO) is a well-known II–VI semiconductor with direct band gap around 3.37 eV and large exciton binding energy (60 meV) at room temperature [1]
Two sample series of the ternary compound ZnOTe in thin films form were grown using DC magnetron cosputtering technique starting from highly pure independent zinc and tellurium targets in a controlled oxygen/argon atmosphere at room temperature
ZnO band gap energy obtained from PL spectra was estimated at 3.26 eV, well in agreement with previously obtained values

Summary

Introduction

Zinc Oxide (ZnO) is a well-known II–VI semiconductor with direct band gap around 3.37 eV and large exciton binding energy (60 meV) at room temperature [1]. The large range of industrial uses is strongly dependent on the experimental technique, parameters, preparation, and post-treatment of the grown samples etc Optimizing these factors is the greatest challenge in obtaining these materials’ benefits. RF magnetron sputtering using two independent targets of ZnTe and ZnO was used [28] All these techniques were used indistinctly for both ZnO-based thin films and nanostructured compounds. The main objective of this basic research was to study the effects of low and middle Te concentrations in the ZnO network which currently constitute an interesting scientific issue For this purpose, ZnO:Te thin films with different Tellurium atomic content and without any intentional heating were grown by using two separate, highly pure, and independent targets of Te and Zn. For this purpose, ZnO:Te thin films with different Tellurium atomic content and without any intentional heating were grown by using two separate, highly pure, and independent targets of Te and Zn Under these experimental conditions, we were able to get high control of the ZnOTe thin film composition. As far as we know, this is the first report of the growth and procedures to obtain ZnOTe alloys by DC magnetron cosputtering technique with independent Zn and Te cathodes

Methods

Results

Conclusion