Optical and structural properties of undoped and palladium doped indium tin oxide films grown by pulsed laser deposition

The purpose of the present investigation is the fabrication of undoped and palladium doped indium tin oxide films by pulsed laser deposition and the analyses of their optical, waveguide and structural properties in view of optical sensor applications. The films are deposited at oxygen pressure from 5 to 20 Pa and substrate temperature between 200 and 450 deg. C. Palladium is used as a dopant since it is critical in improving the sensor's properties. The X-ray diffraction spectra show that all films are polycrystalline with preferential [1 1 1] orientation. The optical transmittance measured in the visible region has maximum values of 85-90% for films grown at oxygen pressure 15 Pa independently of the substrate temperature used. SEM, AFM and optical and investigations revealed that indium tin oxide films with 1 wt.% Pd have higher transmittance and better surface morphology than those with 3 wt.% Pd concentration. ITO films with minimum propagation losses of 2 dB cm-1 were deposited at substrate temperature 200 deg. C and oxygen pressure 5 Pa, but doped ITO films with minimum propagation losses were obtained at 400 deg. C and 15 Pa