Study on electrical properties of n-type transparent and conductiveCdIn22O44 thin film and the optimum preparation parameters for large- area film

Abstract

Transparent and conductive oxides CdIn22O44 thin films wer e prepared by radio-frequency reactive sputtering from a Cd-In alloy target in Ar+O22 atmosphere. The structure and constitution of the films were obtained by x-ray diffraction. All films prepared contained the polycrystalline CdIn22O44 while a secondar y crystalline phase of CdO was also present. Theoretically, it is proposed that three types of point defects play the most important role in affecting the carri er concentration and the scattering of conduction electrons, namely, oxygen vaca ncies, impure point defects and dissolved surplus oxygen trap centers. By the me asurement and computing for Hall and themopower, we could get carrier concentrat ion, Hall mobility, effective mass and relaxation time. At the same time, this p aper formulated the effect on optical band-gap due to band-gap narrowing and B urstein-Moss (B-M) shift, and a proper substrate temperature, namely Tss≈280℃, was used in sputtering for getting higher transmittance of light. Analy sis indicated that better thin films were prepared at oxygen density of 8%. By p ost-deposition heat treatment, a charge-carrier mobility of 31×10-4-4m2/V·s and resistivity of 189×10-5Ω·m were obtained, and the thin films also retain high visible transmittance.