Oxidation of MBE-Grown ZnTe and ZnTe/Zn Nanowires and Their Structural Properties.

Katarzyna Gas,Wojciech Szuszkiewicz,Maciej Sawicki,Slawomir Kret,Tomasz Wojtowicz,Eliana Kamińska,Wojciech Zaleszczyk

doi:10.3390/ma14185252

Katarzyna Gas, Wojciech Szuszkiewicz + Show 5 more

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https://doi.org/10.3390/ma14185252

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Abstract

Results of comparative structural characterization of bare and Zn-covered ZnTe nanowires (NWs) before and after thermal oxidation at 300 °C are presented. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, and Raman scattering not only unambiguously confirm the conversion of the outer layer of the NWs into ZnO, but also demonstrate the influence of the oxidation process on the structure of the inner part of the NWs. Our study shows that the morphology of the resulting ZnO can be improved by the deposition of thin Zn shells on the bare ZnTe NWs prior to the oxidation. The oxidation of bare ZnTe NWs results in the formation of separated ZnO nanocrystals which decorate crystalline Te cores of the NWs. In the case of Zn-covered NWs, uniform ZnO shells are formed, however they are of a fine-crystalline structure or partially amorphous. Our study provides an important insight into the details of the oxidation processes of ZnTe nanostructures, which could be of importance for the preparation and performance of ZnTe based nano-devices operating under normal atmospheric conditions and at elevated temperatures.

Highlights

We report the results of our studies of the low-temperature oxidation of molecular beam epitaxy (MBE)-grown ZnTe-based nanowires
The base ZnTe NWs are grown on GaAs (111)-oriented substrates by molecular beam epitaxy (MBE) at 400 ◦ C employing a gold-catalyzed vapor-liquid-solid (VLS) mechanism, following the method detailed in references [26,27]
The as-grown material is depicted in the left panels, whereas the morphology of the corresponding NWs after the oxidation is shown in the right panels

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, Switzerland.Attribution (CC BY) license (https://creativecommons.org/licenses/by/ 4.0/).One-dimensional (1D) semiconductor nanostructures, such as nanowires (NWs), nanotubes, nanorods, and others, have attracted a great deal of attention due to their potential applications as building blocks in electronic and optoelectronic nanodevices [1]. There are two major approaches to the fabrication of these 1D structures. The “top-down” approach uses nano-lithography followed by a suitable chemical etching. In the “bottom-up”

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