Investigation on dark current and photoresponsivity of flexible single-crystal semiconductor photodetectors on plastic substrates

High-performance flexible photodetectors have drawn increasing attentions, and the dark current and photoresponsivity are the major performance parameters. Investigations on the influence factors and operation mechanisms of the dark current and photoresponsivity for the flexible photodetectors are highly desirable. In this paper, flexible single-crystal Si and Ge photodetectors on polyethylene terephthalate (PET) substrates were fabricated and characterized. The transferred single-crystal Si and Ge nanomembranes on PET substrates showed good crystal quality by x-ray diffraction and Raman spectroscopy. Based on the experimental and modeling results, the performance dependences on semiconductor materials, doping concentrations, dimensions of the intrinsic region, incident light wavelength and power were presented. The influential factors and the operation mechanisms for the performance dependence were discussed by analyzing the electric field distribution, energy band distribution, recombination rate, absorption coefficient, penetration depth and photogeneration rate based on the device model. The results provided useful guidelines to design high performance flexible single-crystal semiconductor photodetectors.