Characterization of n-Type and p-Type ZnS Thin Layers Grown by an Electrochemical Method
Electrodeposition of n-type and p-type thin-film layers of ZnS was carried out using a simple two-electrode system and aqueous solutions of ZnCl2 and (NH4)2S2O3 with different Zn2+ concentrations. X-ray diffraction measurements show that the ZnS layers deposited from both solutions are amorphous. Optical absorption measurements show low absorbance of the layers with energy bandgap in the range of 3.68 eV to 3.78 eV after postdeposition annealing. Photoelectrochemical cell measurements show that both n-type and p-type ZnS thin layers can be electrodeposited by simply changing the concentrations of the deposition solutions. With higher Zn2+ concentration in the bath, n-type ZnS films were deposited, while p-type ZnS films were deposited with lower Zn2+ concentration. The estimated resistivity of layers from both solutions using I–V measurements were 3.0 × 104 Ω cm and 2.0 × 104 Ω cm, respectively, for n-ZnS and p-ZnS. Scanning electron microscopy shows that the deposited films consist of particles with good surface coverage of the glass/fluorine-doped tin oxide substrate.