Optical and Electrical Properties of Copper Doped Cadmium Oxy-Sulphide Quaternary Thin Films by MOCVD Technique

Sabur Abiodun Ayinde

doi:10.11648/j.ijmsa.20170604.19

Abstract

A prepared single solid source precursor was used for the deposition of copper doped oxy-sulphide thin films on glass substrate by MOCVD technique. This was achieved by the pyrolysis of the prepared precursors at 420°C with a flow rate of 2.5 dm<sup>3</sup>/min for 2 hours. The deposited films were characterized using Rutherford Backscattering Spectroscopy (RBS), Scanning Electron Microscopy (SEM), UV-visible spectrophotometry and four point probe method. RBS analysis showed that the expected elements are present while the thickness was estimated to be 889 nm. The SEM images of the deposited film showed a fine structure with densely packed grains of uniform grain size of about 80 nm, well distributed throughout the entire substrate which is polycrystalline in nature. The film revealed an average transmittance of 80% in the visible region with a direct bandgap of 2.41 eV. The absorbance of the film was observed to be low in the visible and near-infrared regions, and high in UV region. The values of 1 <img width="80" height="16" src="http://article.sciencepublishinggroup.com/journal/123/1231164/image001.png"/> and <img width="62" height="16" src="http://article.sciencepublishinggroup.com/journal/123/1231164/image002.png"/> were obtained as the sheet resistance and resistivity of the film respectively. The deposited quaternary thin film is found to be a promising candidate as window layer and absorber layer for cost effective photovoltaics.

Highlights

Cadmium Sulphide (CdS) belongs to group II-IV semiconductor with wide band gap energy (2.42 eV) [1] covering the visible spectrum range
The aim of this work is to study the morphological, optical and electrical properties of copper doped cadmium oxy-sulphide thin films prepared by metal organic chemical vapour deposition (MOCVD) technique, such that it could be used as an absorber layer for a typical solar cell
Attempt has been made in this study to deposit copper doped cadmium oxy-sulphide thin films from a single solid source precursor using MOCVD method

Summary

Introduction

Cadmium Sulphide (CdS) belongs to group II-IV semiconductor with wide band gap energy (2.42 eV) [1] covering the visible spectrum range. It is a direct band gap material and one of the most useful semiconductor materials with its wide range of applications in semiconductor devices such as fabrication of solar cells as optical windows [2], piezo-electronic and optoelectronic [3] devices such as thin film optical integrated circuits. In the case of thin film solar cells, it has been reported that efficient thin film solar cells are obtained using CdS as an n-partner. The highest efficiency so far reported for CdS thin film solar cells is 16.5% [11]. Chalcogenides copper sulphide (CuS) have found wide range application in the fabrication of microelectronic devices, optical filters as well as in low

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