Preparation and Characterization of CoevaporatedCd1−xZnxSAlloy Thin Films

Wei Li,Lili Wu,Lianghuan Feng,Zhen Sun,Jingquan Zhang,Jiayi Yang

doi:10.1155/2011/969214

Abstract

Cd1-xZnxSthin films have been prepared by the vacuum coevaporation method. The structural, compositional, and optical properties ofCd1-xZnxSthin films have been investigated using X-ray diffraction, X-ray fluorescence, and optical transmittance spectra. As-depositedCd1-xZnxSthin films are polycrystalline and show the cubic structure forx=1and hexagonal one forx<1with the highly preferential orientation. The composition ofCd1-xZnxSthin films determined from Vegard's law and quartz thickness monitors agrees with that determined from the X-ray fluorescence spectra. Optical absorption edge of optical transmittance forCd1-xZnxSthin films shows a blue shift with the increase of the zinc content. The band gap forCd1-xZnxSthin films can be tuned nonlinearly withxfrom about 2.38 eV for CdS to 3.74 eV for ZnS. A novel structure for CuInS2-based solar cells with aCd0.4Zn0.6Slayer is proposed in this paper.

Highlights

ZnS-based II-VI materials can form ternary alloys, such as Cd1−xZnxS, with a direct fundamental band-gap range from 2.4 to 3.7 eV at room temperature
From X-ray diffraction (XRD) patterns, one can see that the diffraction angle (2θ) shifts towards a slightly higher angle with increasing x (Zn content) in the thin films
Cd1−xZnxS thin films with the required composition have been successfully deposited on glass substrates by the vacuum coevaporation method

Summary

Introduction

ZnS-based II-VI materials can form ternary alloys, such as Cd1−xZnxS, with a direct fundamental band-gap range from 2.4 to 3.7 eV at room temperature. The energy position of the conduction band is changed primarily by varying the Zn content These materials have potential applications for efficient electron-confined structures, photovoltaic heterojunction, and electro-optical devices. The replacement of CdS with the higher band-gap Cd1−xZnxS has led to a decrease in window absorption losses and has resulted in an increase in the shortcircuit current [1]. This Cd1−xZnxS ternary compound is a useful buffer material for fabrication of p-n junctions without lattice mismatch [2].

Experimental Details

Results and Discussion

Conclusions