Preparation and Characteristics Study of Polystyrene/Porous Silicon Photodetector Prepared by Electrochemical Etching

Novel doped polystyrene (PS)/porous silicon (PSi) heterojunction photodetector prepared by solution cast and electrochemical techniques is proposed here. The structural and optical properties of polystyrene film and porous silicon surface were investigated using X-ray diffraction (XRD), scanning electron microscope, Fourier transformed infrared (FT-IR), and UV-Vis spectrophotometer. XRD data confirmed that the PS film was amorphous in nature and the porous silicon was nanocrystalline. The optical properties showed that the average optical transmittance and the optical energy gap of PS film were 80% and 3.2eV, respectively. The electrical properties revealed that the electrical resistivity and mobility of the doped polystyrene film were 3x10(4)cm and 4.5x10(-5)cm(2)V(-1)s(-1), respectively. Photoluminescence PL of porous silicon was investigated. Dark I-V characteristics revealed that the PS/PSi heterojunctions prepared with an etching time of 5min exhibited better-rectifying properties than that of PS/PSi heterojunction prepared at 10min. The figures of merit of the photodetectors such as spectral responsivity, external quantum efficiency, and detectivity were investigated and compared with Au/PSi Schottky photodetectors. Minority carrier lifetime of the photodetectors was measured using open circuit voltage decay method.