Photosensitive properties of Schottky type photodiodes prepared by spin coating of isoniazid Schiff base thin film on p-Si

In this study, a layer of isonicotinohydrazide and pyrene-based Schiff base (PyMIs) was formed on the front side of a p-Si semiconductor using the spin coating method, and an Al/PyMIs/p-Si/Al diode was fabricated. The I-V characteristics of the fabricated diode were measured under dark and from 20 to 100 mW/cm2 illumination intensities for both forward and reverse bias. Diode parameters, including saturation current ( I_0 ), ideality factor (n), and barrier height ( φ_b ) were investigated for all measurements based on thermionic emission theory. The values n changed from 2.51 to 2.05, and the φ_b changed from 0.77 eV to 0.86 eV as light intensity increased from dark to 100 mW/cm2. The series resistance ( R_s ) values of the diode were investigated using the modified Norde’s function and Cheung’s functions. An analysis of the forward log( I ) - log( V ) plot of Al/PyMIs/p-Si (MOmS)-type diode specified the carrier transport domination by ohmic conduction in the lower bias regions, by the space-charge-limited current (SCLC) at medium bias regions and the trap-charge limit current (TCLC) transport mechanism at higher bias regions. The fabricated diode exhibited typical photodiode behavior with reverse current values increasing from 9.13 × 10− 6 A to 1.05 × 10− 4 A, respectively. Furthermore, I-V characteristics illuminated from 20 to 100 mW/cm2 were also studied, and they indicated that the Al/PyMIs/p-Si diode could operate in a photovoltaic regime.