Limiting Effect of Interface States Density on Photoelectric Properties of Sol–Gel n-ZnO/p-Si Heterojunction

An n-ZnO/p-Si heterojunction was elaborated using the sol–gel spin-coating technique and simulated by two-dimensional (2D) numerical simulations. The structural, optical, electrical, and photoelectrical properties were investigated. X-ray diffraction (XRD) analysis confirmed the hexagonal wurtzite structure of ZnO. Scanning electron microscopy (SEM) analysis revealed a homogeneous granular structure with mean grain size of 71.42 nm. High optical transmittance and low reflectance in the visible range were measured by ultraviolet–visible (UV–Vis) spectrophotometry. Photoluminescence (PL) measurements revealed the presence of VO, VZn, Zni, and OZn intrinsic defects. Hall-effect measurements showed a charge carrier density of $$1.29\times {10}^{19}\,{\text{cm}}^{-3}$$ , mobility of $$1.41\times {10}^{-2}\,{\text{cm}}^{2}{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$$ and resistivity of $$34.25\,\Omega\,\mathrm{cm}$$ in the ZnO layer. Under illumination, the n-ZnO/p-Si structure showed the following photoelectric parameters: JSC = 4.62 × 10–5 A/cm2, Voc = 0.385 V, and fill factor (FF) of 31.45%. Finally, simulations using Atlas Silvaco software revealed the existence of an interface states density of around 5 × 1014 cm–2, which limits the photoelectric performance of the structure.