Influence of cadmium content on the microstructure characteristics of dip coated nanocrystalline Zn1−xCdxS (0 ⩽ x ⩽ 0.9) and their heterojunction applications

Abstract

Nanocrystalline Zn1−xCdxS (0⩽x⩽0.9) thin films were prepared by dip-coating method. The compositional analyses were made by the energy dispersive X-ray technique (EDX). X-ray diffraction analyses (XRD) of the prepared samples were performed to investigate the crystalline structure and determine the main structural parameters using Williamson–Hall (W–H) model. The surface morphology and crystalline structure of nanocrystalline Zn1−xCdxS thin films were studied using the scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The estimated average crystallite size of Zn1−xCdxS by W–H analysis were compared with TEM results. It is found that the average crystallite size measured by W–H analysis is in good agreement with TEM results. The capacitance–voltage (C–V) characteristics of n-Zn1−xCdxS/p-Si heterojunction were measured at different temperatures ranging from 300 to 400K under dark condition. The dependence of C−2 on V for the heterojunctions was found to be almost linear which indicates that the prepared heterojunctions are abrupt and then the essential junction parameters were obtained. The built-in potential (Vb), the donor carrier concentration (ND) and the width of the depletion region (W) were studied as a function of Cd-content.