Photon-assisted tunneling for sub-bandgap light detection in silicon PN-doped waveguides

Abstract

We demonstrate silicon ridge waveguide photo-detectors capable of sub-bandgap light absorption and avalanche multiplication. The proposed waveguide photo-detectors contain highly doped PN junction, where a strong electric field can generate the photon-assisted tunneling current for sub-bandgap light incidence and amplify the generated photo-current by the avalanche multiplication effect. The voltage-dependent sub-bandgap absorption coefficient and multiplication gain are experimentally evaluated for various doping configurations to find optimal photo-response with low dark currents. As a result, our representative silicon waveguide photo-detector gives sub-bandgap responsivities of ~10 and ~2 A/W under the applied reverse bias voltage of -8.3 V for near-infrared wavelengths of 1.31 and 1.52 μm, respectively. The voltage-dependent frequency photo-response is also demonstrated with theoretical verification.

High photoresponsivity and broadband photodetection with a band-engineered WSe2/SnSe2 heterostructure

“…The electron and hole wave functions have a tail which extends into the band gap, enhancing the e-h interactions with subbandgap photons. 59 Thus, under such a high built-in electric field, our device has the potential to allow the photo-excited carrier generation with a photon energy smaller than the intrinsic band-gap of WSe 2 and transfer to the conduction band of SnSe 2 . 53,60 The magnitude of the photocurrent under the 980 nm laser is around 2.6 times larger than that generated under the 1550 nm laser because the photon energy of 980 nm is higher than that of 1550 nm.…”

Photodetector based on heterostructure of two-dimensional WSe2/In2Se3

“…The edges of the conduction and the valence band are tilted along the direction of the electronic field. The wave functions of the electron and hole can extend a tail into the forbidden band increasing the e-h interactions with the sub-band gap photons [52][53][54]. Thus, a photon with the energy smaller than the band gap of WSe 2 and In 2 Se 3 can allow the photo-excited carrier generation.…”

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

“…Detectors for broadband optical signals consist of two main classes. One is narrow band gap semiconductors (such as germanium, , group III–V/II–VI compounds, , other narrow band gap two-dimensional materials, and colloidal quantum dots with tunable band gaps , ) and the other is all-silicon detectors which utilize two-photon absorption, , sub-band gap absorption, , surface-state absorption, , and optically assisted carrier tunneling absorption physical effects of silicon to achieve light absorption below the energy gap. Considering requirements such as room-temperature operation, nontoxicity, and low cost, all-silicon detectors offer unparalleled advantages over these narrow band gap semiconductor detectors.…”