Improved photoresponse of porous silicon photodetectors by embedding CdSe nanoparticles

Abstract

The paper presents the effect of incorporating colloidal cadmium selenide nanoparticles on the characteristics of porous silicon Al/porous Si/p-Si photodetectors prepared with 7 mA/cm² electrochemical etching for 15 min. The spherical cadmium selenide nanoparticles of size 35-60 nm, synthesized by laser ablation in methanol, had covered the pore walls of porous silicon matrix. Structural, morphological and optical properties of porous silicon and cadmium selenide nanoparticles were characterized by X-ray diffraction, photo-luminescence, Fourier transformation infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy and UV-Vis spectrophotometer. Electrical and photosensitivity of porous silicon photodetectors have been investigated before and after the embedding of cadmium selenide nanoparticles. The ideality factor of porous silicon has decreased after the incorporation of cadmium selenide nanoparticles in porous silicon. Photodetector sensitivity has increased from 0.5 to 0.8 A/W at 800 nm after embedding CdSe NPs in silicon pores.