Preparation And Properties Study Of Transparent Conductive In₂O₃:Sn And ZnO:Al Thin Films

Due to big carrier concentration and optical band gap,transparent conductive oxide thin films exhibit outstanding optical and electrical properties,such as low resistivity and high transmittance in the visible range etc．At present,this kind of material system include In2O3,SnO2,ZnO and dopant system In2O3:Sn(ITO),SnO2:Sb,SnO2:F,ZnO:Al(ZAO) etc．Among them,SnO2(TO) and In2O3:Sn(ITO) films have been widely used in liquid crystal display and solar cell as transparent electrode．Al-doped ZnO films show good electrical and optical properties and emerge as a potential alternative candidate for ITO films．Furthermore,they offer a number of advantages compared to the predominant ITO films nowadays:(i) cheap and abundant raw materials；(ii) nontoxicity；(iii) good stability in hydrogen plasma,which is of significance for applications related to amorphous silicon solar cell．Many processes are used to prepare transparent conductive films such as magnetron sputtering,vacuum reactive evaporation,chemical vapor deposition,sol-gel,laser-pulsed deposition．Among these methods,magnetron sputtering is the most widely used technique for preparing thin films owing to its high deposition rate and good uniformity etc．ITO and ZAO films were prepared by RF magnetron sputtering in pure argon gas atmosphere using In2O3 and ZnO target mixed with SnO2(10wt%) and Al2O3 (3wt%) respectively,and the effect of process parameters on the structural,electrical and optical properties of ITO and ZAO films werestudied．In addition,ZAO films were deposited by reactive magnetron co-sputtering from two separate metallic targets of Zn(DC) and Al(RF) in Argon and oxygen atmosphere． During deposition,Al concentration was determined by the RF power of Al target．ITO thin films deposited at the substrate temperature of 300℃ have preferred orientation of (222),the lattice shrinkage is ascribed to the replacement of Sn4+ for In3+,the visible transmittance of 80% and the minimum specific resistance of 6.8×10-4Ωcm were obtained．The peak position of ZAO films prepared at low temperature shifts to the lower angle comparable to that of bulk ZnO due to the residual stress；as-deposited post-annealed ZAO films was polycrystalline with the hexagonal crystal structure and had a strongly preferred orientation of c axis perpendicular tothe substrate surface,the minimum resistivity and average transmittance to the visible light are 7.5×10-4Ωcm and 85% respectively。During deposition of ZAO films,oxygen and substrate temperature have great influence on the optical and electrical properties．The surface sheet resistance decreases with increasing RF power of Al target,ZAO thin films show minimum resistivity at the power of 120W．The conductivity get worse with further increase in RF power．...