Optical properties of prussian blue thin films and electrical characteristics of Ag/prussian blue/p-Si/Al photodetectors for low-optical power latch-switching applications

The influences of film thickness on the energy bandgap and optical dielectric loss of Prussian Blue (PB) were examined to fabricate Ag/Prussian Blue (PB)/p-Si/Al photodetectors. The morphological characteristics of the spin-coated Prussian Blue (PB) nanostructured films were investigated by FESEM, and 30% of the analyzed particle size distributions were equal to 70 +/- 3 nm. An empirical mathematical relationship that correlates the estimated bandgap (E-g eV) values to the film thickness (d nm) is concluded. An empirical equation correlates the estimated energy bandgap to the film thickness, d(nm) = QEg(-s) where: Q = 15.7 and S = -3.63 with standard errors 4 and 1, respectively. The extracted bandgap energies are equal to 3.622, 3.630, 3.641 and 3.678 eV with indirect transition type for the fabricated Prussian Blue (PB) films with thicknesses equal to 76, 92, 109 and 125 nm, respectively. The real part of the refractive index in the near-infrared region is parameterized by using different theoretical [(Drude-Voigt), analytical Cauchy and Forouhi and Bloomer] formulas. When 2.33 eV > Tan delta > 1.52 eV, the induced electric dipoles increase rapidly, and the value of T decreases from 0.43 to 0.03 with the increase of the film's thickness from 76 to 125 nm, respectively. The plots of the measured parallel capacitance, C-S, conductance, and G(p) illustrate a memory hysteresis loop, and the recorded data is analyzed and simulated by impedance spectroscopy analysis. The fabricated Ag/Prussian Blue (76 nm)/p-Si/Al devices are investigated in dark and illumination conditions. The evaluated responsivity showed a linear mathematical relation against the reverse applied voltage ranging from 1.95 to - 0.9 V. This optical switching region may be helpful for lower power switching optoelectronics (from 6 to 18 mW/cm(2)).