Bendable Photodetector on Fibers Wrapped with Flexible Ultrathin Single Crystalline Silicon Nanomembranes

Abstract

Silicon (Si) nanomembranes (NMs) enable conformal covering on complicated surfaces for novel applications. We adopt classical fibers as flexible/curved substrates and wrap them with freestanding ultrathin Si-NMs with a thickness of ∼20 nm. Intrinsic defects in single-crystalline Si-NMs provide a flow path for hydrofluoric acid (HF) to release the NM with a consecutive area of ∼0.25 cm. Such Si-NMs with ultralow flexural rigidities are transferred onto a single-mode fiber (SMF) and functionalized into bendable photodetectors, which detects the leaked light when the fiber is bent. Our demonstration exemplifies optoelectronic applications in flexible photodetector for Si-NMs in a three-dimensional (3D) geometry.

Low‐dimensional nanomaterial/Si heterostructure‐based photodetectors

“…No obvious performance failure was observed with a bending radius less than 3 cm. To supplement these flexible planar devices, Mei's group wrapped optical single‐mode fibers with Si‐NMs to fabricate wire‐shaped Si‐based photodetectors (Figure B) . Despite the inferior performance in terms of the on/off ratio, the demonstrated photodetector still had the potential to detect light leakage in a bendable optical fiber.…”

“…Copyright 2018, Wiley‐VCH. B, Schematic diagram and optical image of a Si‐NM‐based photodetector on a bendable optical fiber . Copyright 2017, American Chemical Society…”

Assembly and Self‐Assembly of Nanomembrane Materials—From 2D to 3D

“…Panel (ii) of Figure b shows ratio of photocurrent and dark current varying with the curvature of fiber, and the calculated bending loss caused by curvature is also showed for comparison. A good agreement indicates that light leakage is absorbed by the Si nanomembrane, leading to sensitive photodetection …”

“…Here, the device is constructed by assembling Si nanomembrane on a 20 cm long fiber which guides light. As shown in panel (i) of Figure b, the Si nanomembrane contacts with silver paste to form metal–semiconductor–metal photodetector and the channel length is ≈100 µm . The small thickness of the Si nanoemmrbane and the wavy/wrinkle structure therein guaranteed very good flexibility and bending of the fiber cannot produce observable crack.…”

“…The small thickness of the Si nanoemmrbane and the wavy/wrinkle structure therein guaranteed very good flexibility and bending of the fiber cannot produce observable crack. It was noticed that when the fiber was bent, some portion of light was likely to leak from core to the outer surface and then absorbed by the device, which can be detected . Panel (ii) of Figure b shows ratio of photocurrent and dark current varying with the curvature of fiber, and the calculated bending loss caused by curvature is also showed for comparison.…”