Properties of indium oxide thin films prepared by reactive electron beam evaporation technique for EMI control

The phenomenon of electromagnetic interference (EMI) is well known. For the specific case of video displays the EMI control requires transparency in the visible spectrum. In the present paper, the EMI shielding properties of indium oxide (IO) thin films have been studied. These IO thin films of thickness ranging between 100-150 nm have been prepared on glass substrates by the reactive electron beam evaporation technique. The electrical and optical properties of these IO films have been studied by varying the substrate temperature. The films have a resistivity of the order of 1.0×10^-4 ohm cm and an optical transparency of 85%. It is found that the EMI shielding efficiency (SE) of IO films (of 100 nm thickness) is very much comparable to that of the silver coated metal sheet in the measured frequency range 1 MHz to 800 MHz. In order to understand these results, preliminary analyses have been carried out by evaluating the conducting carrier density and the AC magnetic susceptibility measurements. The analyses clearly indicate the required properties of IO films for EMI applications.