Strain modulation in crumpled Si nanomembranes: Light detection beyond the Si absorption limit

Abstract

Although Si is extensively used in micro-nano electronics, its inherent optical absorption cutoff at 1100-nm limits its photonic and optoelectronic applications in visible to partly near infrared (NIR) spectral range. Recently, strain engineering has emerged as a promising approach for extending device functionality via tuning the material properties, including change in optical bandgap. In this study, the reduction in bandgap with applied strain was used for extending the absorption limit of crystalline Si up to 1310 nm beyond its intrinsic bandgap, which was achieved by creating the crumpled structures in Si nanomembranes (NMs). The concept was used to develop a prototype NIR image sensor by organizing metal-semiconductor-metal–configured crumpled Si NM photosensing pixels in 6 × 6 array. The geometry-controlled, self-sustained strain induction in Si NMs provided an exclusive photon management with shortening of optical bandgap and enhanced photoresponse beyond the conventional Si absorption limit.

Strain-Engineering-Driven Photomechanical–Photoelectric Coupled Flexible Photodetector Based on Hexagonal Silicon Nanowire Films

“…The reported responsivities for wavelengths 1310 and 1550 nm are ∼35 and 4 μA·W –1 , respectively, which are low but demonstrate the near-infrared sensing capability of silicon under strain. Recently, Jong-Hyun Ahn reported a monocrystal silicon photodetector with a high responsivity of 33 mA·W –1 used for extending the absorption limit of crystalline Si up to 1310 nm beyond its intrinsic band gap, which was achieved by creating the wrinkled structures in monocrystal silicon nanomembranes. We had recently prepared narrow band gap hexagonal silicon nanowires and developed a very promising simple hexagonal silicon nanowire device for near-infrared (1319 nm) detection .…”