ELECTRICAL, OPTICAL, AND STRUCTURAL-PROPERTIES OF INDIUM-TIN-OXIDE THIN-FILMS DEPOSITED ON POLYETHYLENE TEREPHTHALATE SUBSTRATES BY RF-SPUTTERING

Indium-tin-oxide (ITO) is a transparent conducting material which is d eposited as a thin film on glass substrates for use in opto-electronic devices. However, there are several applications for which ITO films on polymeric substrates are desirable. The sheet resistance, optical t ransmittance, and microstructure of as-deposited ITO thin films on unh eated polyethylene terephthalate substrates were studied using rf sput ter deposition. During separate deposition runs, the partial pressure of oxygen was varied from 5% to 20% and the deposition time was varied from 15 to 120 min. No significant variations are observed in the she et resistance with respect to oxygen partial pressure; however, change s in sheet resistance were observed in ITO films deposited on differen t substrates for short deposition times (15 min). Additionally, the th ickness of the film (assumed to be proportional to the deposition time ) is shown to have a considerable impact on the sheet resistance and t he optical transmittance. The x-ray diffraction data coupled with the sheet resistance data suggest that ITO films exhibiting a preferred (4 00) orientation have the highest sheet conductance. The changes observ ed in the sheet resistance, optical transmittance, and the refractive index due to the thickness of the film or oxygen partial pressure duri ng deposition are explained on the basis of surface roughness, free ca rrier concentration, and the microstructure of the film. (C) 1998 Amer ican Vacuum Society.