Influence of the distance between nozzle and substrate on the structural, photoluminescence, and detector characteristics of p-NiO/n-Si hetero-junction deposited by spray pyrolysis method

In the present investigation, p-NiO has been deposited on n-Si (100) substrate by the spray pyrolysis method. The effect of the distance between the substrate and the nozzle on the structural, photoluminescence, and detection properties has been well inspected. The highest film nucleation and the degree of crystallization were found at a distance between the nozzle and the substrate of 25 cm which is the preferred one that can affect the performance of the detector. The XRD analysis proved the polycrystalline system with a cubic structure for NiO. The FESEM analysis manifested nano and micro particles distributed on the Si layer, and the micro particles have porous like structures that play a significant role as photons guider. The photoluminescence measurement evinced three main peaks at the UV and visible regions of the electromagnetic spectrum, which is related to the near band edge emission and defects within the crystal, respectively. The I-V characteristics revealed a good conductivity under the UV illumination, and the highest current was recorded by a sample when the distance was 25 cm. The responsivity elucidated a high value at the UV region with 6.5 mA/W, and the current-time properties demonstrated good reproducibility, high stability and photoresponse, and rapid response, and recovery times of 0.375 s and 0.791 s, respectively at a lower bias voltage of 1.5 Volt under the UV photons source.