Enhanced UV detection of ZnSnO3 hollow spheres: Dark current inhibition from excitons and homostructures based on excitation of oxygen vacancies

With the presence of triethanolamine (TEOA) and N,N-Dimethylformamide (DMF) as organic functional re-agents, ZnSn(OH)6 precursors composed of hollow-sphere particles were synthesized by co-precipitation method. Microstructure characterization shows that the crystallization growth of ZnSn(OH)6 precursor can be affected by DMF, and that its particle size and average grain size are changed with the mass ratio (x) of DMF to TEOA. Each ZnSnO3 sample (ZSO-x) from its ZnSn(OH)6 counterpart (ZSOH-x) is amorphous structure due to the generation of oxygen vacancy defects. When x is 0.75, the resulting ZSO-0.75 sample has a higher photo-to-dark-current ratio (10,976 at 3 V) than other samples under 365 nm illumination. Further comparison indicates that although ZSO-0.75 sample has more oxygen vacancies than ZSO-0 sample, the dark current of the former is less than that of the latter at the same voltage, which may be related to the formation of tight-binding excitons and homostructures based on the thermal excitation of oxygen vacancies.