CHARACTERIZATION OF INDIUM-DOPED ZINC-OXIDE FILMS DEPOSITED BY PYROLYTIC SPRAY WITH DIFFERENT INDIUM COMPOUNDS AS DOPANTS

The results of a systematic study of the electrical, optical, structur al and surface properties of thin ZnO:In films are presented. The film s were deposited by the spray pyrolysis technique. The spraying soluti on was zinc acetate diluted in methanol and the indium doping was achi eved by adding indium acetate, indium nitrate and indium sulfate at di fferent concentrations up to [In]/[Zn]=3 at%. The films grown at low t emperature show regular and uniformly smooth surfaces with no texturiz ation. Films grown at high temperature show rough surfaces. All the fi lms are polycrystalline and grow with a (101) preferred orientation. T he electrical resistivity measured at room temperature shows a minima in all cases as a function of the substrate temperature, The lowest va lue, rho=2 x 10(-3) Omega cm, was obtained by doping with indium aceta te at a [In]/[Zn]=3 at% concentration. For films about 0.6 mu m thick the average transmittance was better than 85%. A shift in the energy g ap due to a variation in the carrier concentration was observed. This shift is explained with a model in which the Burstein-Moss effect and the electron-electron exchange interaction are considered.