High responsivity, low dark current, heterogeneously integrated thin film Si photodetectors on rigid and flexible substrates

We report thin film single crystal silicon photodetectors (PDs), composed of 13- 25 μm thick silicon, heterogeneously bonded to transparent Pyrex® and flexible Kapton® substrates. The measured responsivity and dark current density of the PDs on pyrex is 0.19 A/W - 0.34 A/W (λ = 470 nm - 600 nm) and 0.63 nA/cm(2), respectively, at ~0V bias. The measured responsivity and dark current density of the flexible PDs is 0.16 A/W - 0.26 A/W (λ = 470 nm - 600 nm) and 0.42 nA/cm(2), respectively, at a ~0V bias. The resulting responsivity-to-dark current density ratios for the reported rigid and flexible PDs are 0.3-0.54 cm(2)/nW and 0.38-0.62 cm(2)/nW, respectively. These are the highest reported responsivity-to-dark current density ratios for heterogeneously bonded thin film single crystal Si PDs, to the best of our knowledge. These PDs are customized for applications in biomedical imaging and integrated biochemical sensing.