Enhanced Light–Tellurium Interaction through Evanescent Wave Coupling for High Speed Mid‐Infrared Photodetection

Abstract

Mid‐infrared (MIR) waveguide‐integrated photodetector is essential for various applications in the fields of sensing and optical communications. However, it is challenging to integrate traditional MIR photoactive materials such as HgCdTe or III−V compounds with complementary metal‐oxide‐semiconductor (CMOS)‐compatible silicon platform due to the lattice mismatch. Tellurium (Te), a novel van der Waals (vdW) material with a narrow bandgap, high carrier mobility, and great air stability, is a promising candidate for high‐performance MIR detection. Here, high‐quality Te nanosheets are synthesized using a hydrothermal method and their carrier dynamics are characterized by transient reflection spectrum. The effect of mobility anisotropy on response speed is investigated intuitively by a free space phototransistor. Combining the strong evanescent wave of a waveguide architecture with the synergy effect between the carrier collection path and the highest mobility crystal orientation in Te, an integrated Te photodetector with enhanced light–matter interaction and reduced carrier transit time is achieved. For the first time, the MIR waveguide‐integrated Te photodetector with a responsivity of 2.3 A W−1 and a bandwidth of 4 GHz at 2015 nm is realized, which is the highest speed MIR photodetector based on narrow bandgap vdW materials to date.

High-Speed Carbon Nanotube Photodetectors for 2 μm Communications

“…The extracted 3 dB bandwidth is 40 GHz at V = −0.2 V. (c) The capacitance of the CNT photodetector extracted from the S 11 parameter. (d) Benchmarking of the 3 dB bandwidth of state-of-the-art high-speed photodetectors at the 2 μm band based on different materials, including silicon, group III–V systems (InGaAs, − InGaAs/GaAsSb, − GaInAsSb), group IV systems (GeSn − ), and two-dimensional materials (graphene, BP, and Te).…”

“…We further benchmark the bandwidth of our CNT photodetector with state-of-the-art high-speed photodetectors at the 2 μm band based on different materials (as shown in Figure d), including silicon, group III–V systems (InGaAs, − InGaAs/GaAsSb, − GaInAsSb), group IV systems (GeSn − ), and two-dimensional materials (graphene, BP, and Te). Our CNT photodetector has a bandwidth of 40 GHz, which is the highest value among all of the results from the previously reported high-speed photodetector in the 2 μm band.…”

“…33 In addition, a waveguide-integrated tellurium (Te) photodetector with a high responsivity of 2.3 A/W and a bandwidth of 4 GHz at 2 μm was developed. 35 However, it remains challenging to achieve CMOS-compatible highperformance photodetectors in the 2 μm band with both high responsivity and a large bandwidth over 30 GHz. Fortunately, CNTs, as one-dimensional semiconductor materials, have a small and tunable bandgap (0.3−1 eV), 36 and they are promising for achieving photodetection beyond 1.55 μm with a suitable diameter distribution.…”

“…Moreover, BP photodetectors exhibit a limited bandwidth of 1.33 GHz at 2 μm due to the large resistance–capacitance (RC) constant . In addition, a waveguide-integrated tellurium (Te) photodetector with a high responsivity of 2.3 A/W and a bandwidth of 4 GHz at 2 μm was developed . However, it remains challenging to achieve CMOS-compatible high-performance photodetectors in the 2 μm band with both high responsivity and a large bandwidth over 30 GHz.…”

TexSe1–x Photodiode Shortwave Infrared Detection and Imaging

“…[32,33] Te photodetectors thus could be compatible with CMOS readout circuitry; [34,35] and 5) Te enjoys large mobility of >1000 cm 2 V −1 s −1 , showcasing a very fast limiting response time of ≈10 ps (Supporting Information) and thereby enabling high-speed imaging. [36,37] Overall, Te and Te-Se alloys have great potential for CMOS-compatible infrared photodetector.…”