Dependence of structural, electrical and optical properties of undoped indium oxide films on thickness

For highly conducting transparent films, thickness is an important parameter. This investigation optimizes the film thickness to obtain high electrical conductivity without appreciably affecting the transparency. Undoped Indium oxide films having different thickness have been deposited on Corning glass (7059) by using the spray pyrolysis technique. Study of the structural, electrical and optical properties of these films reveals that the mobility increases as the film thickness increases till its value is 6500 A° after which the mobility decreases. This behaviour of the mobility is closely related to the crystallinity of the films. A high value of mobility of 53 cm 2V −1s −1 has been achieved. The variation in the number of charge carriers with thickness is small. At 6500 A° the lowest value of resistivity obtained is 9.3 × 10 −4щ cm and the visible transmission is 82 %. Another interesting feature of this work is the improvement in both electrical and optical film properties for the thickest film (1.03 μm) when the substrate temperature is increased from 425°C to 475°C.