Influence of the intrinsic length on p⁺-i-n⁺ Si nanowire avalanche photodetectors on flexible plastic substrates

In this paper, we report the construction of avalanche photodetectors (APDs) consisting of p⁺-type/intrinsic/n⁺-type (p⁺-i -n⁺) Si nanowires (NWs) on a flexible plastic substrate and investigate the photomultiplication characteristics of the APDs with different intrinsic lengths. The maximum avalanche gain and responsivity of the APDs excited by the 633 nm wavelength light are estimated to be 5.9×10⁴ and 1.4×10^-3 A/W, respectively, for an intrinsic length of 0.5 μm. The maximum avalanche gain is associated with an improvement of the photomultiplication properties and results in the efficient generation of photogenerated charge carriers in the intrinsic region of the Si NWs. Furthermore, the breakdown phenomena in our APDs in the flat and upwardly bent states are investigated.