Optoelectronic properties of nanocrystalline tungsten oxide thin films

Tungsten oxide (WO/sub 3/) is an important electronic material investigated for solid state sensors, electrochromic and optoelectronic devices. In this study, optoelectronic properties of nanocrystalline WO/sub 3/ thin films, prepared by vacuum evaporation followed by thermal annealing were investigated. The structural and optoelectronic properties were measured for systematically annealed samples in 100-600/spl deg/C range. It was found that the optical transmittance and electrical conductivity were varied in 10-80% range and 10/sup -3/- 10/sup -8/ (/spl Omega/.cm)/sup -1/ range, respectively, by change of annealing temperature. Study of surface and structural properties reveals that pronounced effect on properties can be made by annealing even at 100/spl deg/C. Results indicated that the properties Of WO/sub 3/ can be tuned by annealing process because of change of crystallinity from amorphous to nanomonocrystalline to polycrystalline structures.