SnOx and a-Si thin-films based photodiode in a flexible substrate for visible spectral region

Abstract

Thin-films based photodiodes are an advantageous alternative to the photodetectors based on semiconductor doping processes, especially in optical sensors implemented on non-semiconductor substrates. This is the first report of a p-i-n junction photodiode, based on n-SnOx/p-SnOx and amorphous silicon (a-Si) thin-films, fabricated in a polymeric, flexible and photosensitive substrate, only considering different annealing conditions and thicknesses of evaporated metallic Sn and sputtered a-Si. Seebeck coefficient measurements were performed, using a custom-built setup, to assess the implementation of n- and p-type thin-films. The obtained Seebeck coefficients were −167 µV/K and +266 µV/K for the n-SnOx and p-SnOx, respectively. X–ray diffraction (XRD) analysis also confirmed the deposition of an a-Si thin-film as the intrinsic layer of the p-i-n junction. The photodiode responsivity and response times were measured, using a custom-built optical setup for the visible spectral region. The measured responsivity (at 0 V reverse bias) was 2.8 µA/W at 572 nm and the rise and fall times were 0.203 s and 0.312 s, respectively. The developed photodiode provides a promising solution for high level light detection applications in flexible optical sensors.