PREPARATION AND PHOTOELECTROCHEMISTRY OF SEMICONDUCTING WS2 THIN-FILMS

Crystalline 2H-WS2 thin films were prepared by thermal decomposition o f amorphous WS3 films sputter-deposited onto a thin Ni layer. Structur al, electrical, and photoelectrochemical properties were investigated. Room temperature photoconductivity and photoelectrochemical response were shown to arise from the same interband transitions as in single c rystals. The photocurrent spectra measured as a function df wavelength revealed a structure due to excitonic transitions. Surface modificati on by adsorption of ethylenediaminetetraacetic acid was shown to incre ase the photocurrent and to reduce the exciton recombination rate. A r ectifying solid-liquid junction, having a barrier height of 0.45 V, wa s formed with the p-WS2 films immersed in the aqueous [Fe(CN)(6)](3-/4 -) redox electrolyte.