Self‐Rolled‐Up Ultrathin Single‐Crystalline Silicon Nanomembranes for On‐Chip Tubular Polarization Photodetectors

Freestanding single‐crystalline nanomembranes and their assembly have broad application potential in photodetectors for integrated chips. However, the release and self‐assembly process of single‐crystalline semiconductor nanomembranes still remains a great challenge in on‐chip processing and functional integration, and photodetectors based on nanomembrane always suffer from limited absorption of nanoscale thickness. Here, a non‐destructive releasing and rolling process is employed to prepare tubular photodetectors based on freestanding single‐crystalline Si nanomembranes. Spontaneous release and self‐assembly are achieved by residual strain introduced by lattice mismatch at the epitaxial interface of Si and Ge, and the intrinsic stress and strain distributions in self‐rolled‐up Si nanomembranes are analyzed experimentally and computationally. The advantages of light trapping and wide‐angle optical coupling are realized by tubular geometry. This Si microtube device achieves reliable Ohmic contact and exhibits a photoresponsivity of over 330 mA W−1, a response time of 370 µs, and a light incident detection angle range of over 120°. Furthermore, the microtubular structure shows a distinct polarization angle‐dependent light absorption, with a dichroic ratio of 1.24 achieved at 940 nm. The proposed Si‐based microtubes provide new possibilities for the construction of multifunctional chips for integrated circuit ecosystems in the More than Moore era. Tubular microtubes of single‐crystalline Si nanomembranes for photodetectors are prepared by a releasing and rolling process. The tubular geometry can trap light to improve the photoresponsivity of ultra‐thin Si nanomembranes and demonstrate the advantage of wide‐angle light coupling. Furthermore, the Si microtubes exhibit obvious polarization angle‐dependent light absorption, enabling polarization‐sensitive detection in the range of visible to near‐infrared.