Improvement of electrical and optical properties of thin ITO films by modifying electrode spacing in DC magnetron sputtering

An important parameter in the deposition of thin-film Indium-Tin-Oxide layers by magnetron sputtering is the spacing between the anode and cathode electrodes, by which the conditions of plasma deposition and the properties of the resulting films are controlled. In this paper, thin ITO films are deposited on glass substrates using the DC-magnetron sputtering technique at RT for different electrode spacing. The thickness of the layers has been measured in the range 110-370 nm. The XRD studies confirm that crystalline structure of ITO is cubic bixbyite. The sheet resistance of the samples prepared at the electrode spacing of 5, 7, 9, and 11 cm, are 17.7, 16, 1723, and 5207 Ω/□, respectively. The transmittance of the films in the spectral range of 400-800nm is 75-85%. The lowest sheet resistance of 16 Ω/□ is obtained at the spacing of 7 cm, having a transparency of 85% and a thickness of 230nm, which confirms that it is appropriate for use as the transparent contact in amorphous silicon solar cells. For such samples the average grain size of the crystallites and the root-mean-square of the roughness of the surface are 50±5 nm and ≈1.97 nm, respectively. The process simulations are also achieved using xpdp1, X'Pert and MATLAB software.