Telecom-Band Waveguide-Integrated MoS₂ Photodetector Assisted by Hot Electrons

Abstract

We report a waveguide-integrated MoS2 photodetector operating at the telecom band, which is enabled by hot-electron-assisted photodetection. By integrating few-layer MoS2 on a silicon nitride waveguide and aligning one of the two Au electrodes on top of the waveguide, the evanescent field of the waveguide mode couples with the Au–MoS2 junction. Though MoS2 cannot absorb the telecom-band waveguide mode, the Au electrode could absorb it and generate hot electrons, which transfer to the beneath MoS2 channel due to the low Au–MoS2 Schottky barrier and generate considerable photocurrent. A photoresponsivity of 15.7 mA W–1 at a wavelength of 1550 nm is obtained with a low bias voltage of −0.3 V, which is also moderately uniform over the wide telecom band. A 3 dB dynamic response bandwidth exceeding 1.37 GHz is realized, which is limited by the measurement instrument. The demonstrated MoS2-based hot-electron photodetector not only outperforms other waveguide-integrated hot-electron photodetectors but also provides a strategy to extend the photodetection spectral range of two-dimensional materials. With the maturity of high-quality large-scale growth and flexible transfer of two-dimensional materials, their hot-electron photodetectors could be integrated on various photonic integrated circuits, including silicon, lithium niobate, polymers, etc.

High-performance hierarchical O-SnS/I-ZnIn2S4 photodetectors by leveraging the synergy of optical regulation and band tailoring

“…15 These handicaps conjointly lead to insufficient light absorption of 2DLM optoelectronic devices. To date, scientists and engineers have explored a variety of optical nano/micro-structures to ameliorate the photosensitivity of 2DLMs, including plasmonic optical antennas, 16 optical waveguides, 17 optical resonant cavities, 18 etc. However, these technologies suffer from their own shortcomings, such as exorbitant material cost, complicated manufacturing, limited enhancement factors, and so on.…”

High-responsivity MoS2 hot-electron telecom-band photodetector integrated with microring resonator

“…2(f). 15,16,18,[34][35][36][37][38][39] These comparisons have proven that the MoS2-based hot-electron photodetector constructed on the MRR possesses excellent electrical and optoelectronic properties.…”

“…15 Recently, our group demonstrated a MoS2-based hot-electron photodetector integrated with an optical waveguide showing 15.7 mA W -1 at a wavelength of 1550 nm. 16 However, their performance could be further improved by utilizing novel device structure/design that enhance the responsivity through increasing light absorption.…”

“…The derived responsivity under -1 V bias is 154.6 mA W -1 at a wavelength of 1516 nm, which is higher than the reported waveguide-integrated hotelectron MoS2 photodetector. 16 To quantify the sensitivity of a photodetector integrated on a waveguide, the normalized photocurrent-to-dark-current ratio (NPDR) is an important metric. As a result of the very low dark current while taking into account the extracted photoresponsivity, the NPDR of our device is remarkably high.…”

Plasmonic Resonance Enabling 2D Perovskite Single Crystal to Detect Telecommunication Light

“…[36] In recent years, hot carrier injection mechanism have also been implemented in 2D material based PDs in order to achieve broadband photoresponses. [38][39][40] For example, Zhang et al reported a hot-electron photodetector based on an Au/MoS 2 hybrid structure integrated with a dielectric microring resonator, which exhibited a high responsivity of 154.6 mA W −1 at the NIR wavelength of 1516 nm. [38] These works provide insights that plasmonic resonance may also functionalize as a promising strategy to extend the response spectrum of 2D perovskite PDs via the generation of hot carriers.…”