Field Effect Phototransistor Based on Thin Film Ag2S Nanocrystals

Silver sulfide as a direct bandgap semiconductor is a promising candidate for fabrication of photodetectors. Although several photodetectors have been reported based on silver sulfide, it has not been used to fabricate a phototransistor device so far. In this paper, fabrication and characterization of a solution-processed field-effect transistor based on Ag2S channel is reported. Ag2S nanocrystals (NCs) were synthesized by a facile method and deposited on a back-gate silicon electrode by spin-coating method. Ag2S NCs channel was shown n-type behaviour and the photoresponse was investigated by mean of a 750 nm wavelength optical source. The fabricated device showed excellent photo responsivity (more than 1 A/W) and high specific detectivity (more than 1012).