UV illumination effects on electrical characteristics of metal–polymer–semiconductor diodes fabricated with new poly(propylene glycol)-b-polystyrene block copolymer

Au/poly(propylene glycol)-b-polystyrene/n-Si (D1) and Au/poly(propylene glycol)-b-polystyrene(HAuCl4 dispersed)/n-Si (D2) diodes were fabricated and their response to UV illumination was investigated using current–voltage measurements in dark and under various illumination intensities (50–250 mW/cm2). Scanning Electron Microscope micrographs of the diodes were provided for morphological analysis. Main electrical parameters; such as ideality factor, barrier height and reverse saturation current, are calculated using Thermionic Emission and Norde’s method, and it was found that they show dependence on UV illumination. Ideality factor values of D1 and D2 diodes in dark is 2.53 and 2.29 whereas they are 3.37 and 3.39 under 100 mW/cm2 UV illumination, respectively. A noticeable effect of UV illumination is the considerable increase of current in the reverse bias region compared with current in dark such that current value increases by ∼103 times with 100 mW/cm2 UV illumination for both diodes. Furthermore, density distribution profiles of surface states in these diodes were also investigated.