Nanostructured-NiO/Si heterojunction photodetector

We investigated the fabrication of heterojunction photodetectors consisting of nanostructured NiO and Si. The spin coating of colloidal Ni(OH)₂ and subsequent thermal annealing at 400 °C in air ambient led to the formation of NiO, in which a number of nanosheets (50–80 nm in size and 11–15 nm in height) were aggregated. The 263-nm-thick NiO showed an average optical transmittance of 83.7% in the wavelength range of 250–1500 nm and exhibited an energy bandgap of 3.69 eV. The nanostructured NiO/Si heterojunction photodetectors exhibited clear rectifying I-V behavior in the dark condition and showed prominent photovoltaic properties under illumination. Time-dependent photocurrent analysis showed that the photoresponsivity was 156.3 µA/W, 418 µA/W and 1.678 mA/W at the source wavelength of 385, 515, and 620 with optical power densities of 1.1, 0.69, and 0.22 mW/cm², respectively.