Obtaining Nanostructured ZnO onto Si Coatings for Optoelectronic Applications via Eco-Friendly Chemical Preparation Routes.

Mirela Petruta Suchea,Cosmin Romanitan,Alexandra Manousaki,Zacharias Viskadourakis,Rabia Ikram,Maria Androulidaki,George Kenanakis,Evangelia Petromichelaki,Petronela Pascariu

doi:10.3390/nano11102490

Abstract

Although the research on zinc oxide (ZnO) has a very long history and its applications are almost countless as the publications on this subject are extensive, this semiconductor is still full of resources and continues to offer very interesting results worth publishing or warrants further investigation. The recent years are marked by the development of novel green chemical synthesis routes for semiconductor fabrication in order to reduce the environmental impacts associated with synthesis on one hand and to inhibit/suppress the toxicity and hazards at the end of their lifecycle on the other hand. In this context, this study focused on the development of various kinds of nanostructured ZnO onto Si substrates via chemical route synthesis using both classic solvents and some usual non-toxic beverages to substitute the expensive high purity reagents acquired from specialized providers. To our knowledge, this represents the first systematic study involving common beverages as reagents in order to obtain ZnO coatings onto Si for optoelectronic applications by the Aqueous Chemical Growth (ACG) technique. Moreover, the present study offers comparative information on obtaining nanostructured ZnO coatings with a large variety of bulk and surface morphologies consisting of crystalline nanostructures. It was revealed from X-ray diffraction analysis via Williamson–Hall plots that the resulting wurtzite ZnO has a large crystallite size and small lattice strain. These morphological features resulted in good optical properties, as proved by photoluminescence (PL) measurements even at room temperature (295 K). Good optical properties could be ascribed to complex surface structuring and large surface-to-volume ratios.

Highlights

As the optical character of the material depends on its structure, size, and shape of building blocks and the resulting surface structure that is a direct consequence of the preparation process, the main goal of this work is to compare the optical properties of various kinds of nanostructured zinc oxide (ZnO) coatings resulting from different kinds of syntheses, including a few green routes
This study focused on the development of various kinds of nanostructured ZnO onto Si substrates via chemical route synthesis using both classic solvents and some usual non-toxic beverages to substitute the expensive high purity reagents acquired from specialized providers
Scanning electron microscopy Scanning Electron Microscopy (SEM) micrographs were analyzed in order to examine the morphology of the prepared samples, while energy dispersive X-ray EDX analysis provided their elemental analysis

Summary

Introduction

As the optical character of the material depends on its structure, size, and shape of building blocks and the resulting surface structure that is a direct consequence of the preparation process, the main goal of this work is to compare the optical properties of various kinds of nanostructured ZnO coatings resulting from different kinds of syntheses, including a few green routes. Nanomaterials 2021, 11, 2490 evaluating PL spectral properties of ZnO layers grown onto Si substrates and relating them to the specific bulk and surface structure via respective synthesis routes. The wurtzite-type structure of ZnO is the most thermodynamically stable form of this semiconductor and exhibits a wide bandgap at around 3.37 eV [1,2]. Many deposition techniques were used during ZnO thin films history: physical growth methods, chemical methods, and combinations of them. Aqueous chemical growth, sol-gel, dip coating, and biosynthesis are the most common ones [3,4,5,6,7,8,9,10,11,12,13,14]

Objectives

Methods

Results

Conclusion