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Abstract: Transparent and conductive/semiconductive undoped indium oxide (InO x ) thin films were deposited at room temperature. The deposition technique used is the radio frequency (rf) plasma enhanced reactive thermal evaporation (rf-PERTE) of indium (In) in the presence of oxygen. The influence of oxygen partial pressure on the properties of these films is presented. The oxygen partial pressure varied between 3×10−2 and 1.3×10−1 Pa. Undoped InO x films, 100nm thick, deposited at the oxygen partial pressure of 6×10−2 Pa show a conductive behaviour, exhibit an average visible transmittance of 81%, a band gap around 2.7eV and an electrical conductivity of about 1100 (Ωcm)−1. For oxygen pressures greater than 6×10−2 Pa, semiconductive films are obtained, maintaining the visible transmittance. Films deposited at lower pressures are conductive but dark. From XPS data, films deposited at an oxygen partial pressure of 6×10−2 Pa show the highest amount of oxygen in the film surface and the lowest ratio between oxygen in the oxide crystalline and amorphous phases. [Copyright &y& Elsevier]

Abstract: Transparent undoped semiconductor indium oxide films were deposited by radio frequency (rf) plasma enhanced reactive thermal evaporation (rf-PERTE) of indium at low substrate temperature. It was experimentally verified that the variation of rf power density has a strong influence on the electrical and structural properties of the films. The thickness of the InO x films is of about 100nm. Results show that InO x films show an average visible transmittance of about 85% and energy gap of about 2.6eV. Structural and electrical conductivity measurements show that films are polycrystalline and there exists a linear variation of conductivity logarithm vs reciprocal of temperature. Electrical conductivity variation of 17.6 to 5.8×10−3 (Ω cm)−1 for films produced at rf power densities ranging from 3.9 to 78.1mWcm−3 was obtained. This controllable semiconductor behavior can therefore satisfy the requirement of a particular application for these type of films. [Copyright &y& Elsevier]

Abstract: Transparent, undoped semiconductive thin films of zinc oxide were deposited by radio frequency plasma enhanced reactive thermal evaporation of zinc rods in the presence of oxygen at room temperature, without any post-deposition annealing treatments. The study of the variation of rf power, in the range 5–200W, on the main properties of these films was made. A decrease of the electrical conductivity of these films with increasing rf power was observed (10−3 to 10−12 (Ωcm)−1), respectively, while the average visible transparency was kept practically constant (≈80%). From this initial study, a set of bottom-gate type thin-film transistors were made using the most promising semiconductor materials. Preliminary I(V) measurements showed all transistors working, with best results obtained from zinc oxide material deposited at the lowest rf power (20W), within the deposition conditions range which leads to semiconductive material. Such devices presented an I on (20V)/I off (−5V) ratio of 6×106 and a field-effect mobility of 0.37cm2/(Vs). [Copyright &y& Elsevier]