Synthesis and characterization of zinc oxide thin films

Abstract

ZnO thin films were prepared by using the DC Reactive Magnetron Sputtering technique. The effect of the working pressure, substrate temperature, Fe-doping, and oxygen concentration in the gas ambient on the structural, optical and electrical properties of the grown films were studied. The working pressure inside the chamber has a vital effect on the quality of the films grown. It turned out that working at an optimum pressure of 400 mTorr, and without intentional substrate heating, gives highly crystalline and highly textured films. Heating the substrate generally reduced crystallinity at such a high pressure, and produced films with smaller grains. Films prepared with only oxygen inside the sputtering chamber were highly resistive, with resistivites in the range 105-106 Ω.cm. Argon must be introduced in the chamber to give conductive films. Optimum oxygen concentration that gave the least resitivities was about 1-1.6%. Fe-doping was tried at optimum conditions of working pressure and substrate temperature. XRD spectra showed that the solubility limit of iron in ZnO is greater than 8%. Energy band gap increased with increasing the iron concentration.