Fabrication of Au/NiO/p-Si/Al Schottky barrier photodiode with NiO interface and determination of electrical and optical parameters from I−V characteristics

This work presents the fabrication and detailed characterization of a Schottky barrier photodiode with a nickel oxide (NiO) interlayer in the Au/NiO/p-Si/Al structure, aiming to surpass the performance limits of conventional silicon-based photodetectors. The wide bandgap (∼3.6 − 4.0 eV) and p-type carrier transport properties of NiO were exploited to optimize the conventional Au/p-Si interface. The device was successfully fabricated using low-cost and scalable methods, and its electrical and photoelectric performance were characterized at room temperature (T = 300 K) under irradiance intensities ranging from 0 mW/cm2 to 100 mW/cm2. The Current-Voltage (I-V) analyses revealed that the diode exhibited significant deviations from the ideal Thermionic Emission (TE) theory: the ideality factor (n) increased from 1.52 in the dark to 4.34 under 100 mW/cm2, while the barrier height (Φb) decreased from 0.78 eV to 0.51 eV. This indicates that the series resistance (Rs) effect and the barrier height irregularities increased under light. Photodetector parameters confirmed that the device has an exponential response to light. The photosensitivity (S) and detectivity (D*) values ​​showed a continuous and exponential increase with increasing light intensity. The device achieved a competitive D* value of 1.75 × 108 Jones at the highest light intensity (100 mW/cm2). This result proves that the Au/NiO/p-Si/Al structure maximizes the signal-to-noise ratio at high light levels and is a suitable candidate for high-sensitivity optical sensing applications.