Ultrasensitive and Self‐Powered Terahertz Detection Driven by Nodal‐Line Dirac Fermions and Van der Waals Architecture

Abstract

Terahertz detection has been highly sought to open a range of cutting-edge applications in biomedical, high-speed communications, astronomy, security screening, and military surveillance. Nonetheless, these ideal prospects are hindered by the difficulties in photodetection featuring self-powered operation at room temperature. Here, this challenge is addressed for the first time by synthesizing the high-quality ZrGeSe with extraordinary quantum properties of Dirac nodal-line semimetal. Benefiting from its high mobility and gapless nature, a metal-ZrGeSe-metal photodetector with broken mirror symmetry allows for a high-efficiency photoelectric conversion assisted by the photo-thermoelectric effect. The designed architecture features ultrahigh sensitivity, excellent ambient stability, and an efficient rectified signal even above 0.26 THz. Maximum responsivity larger than 0.11 A W −1 , response time of 8.3 μs, noise equivalent power (NEP) less than 0.15 nW Hz −1/2 , and demonstrative imaging application are all achieved. The superb performances with a lower dark current and NEP less than 15 pW Hz −1/2 are validated through integrating the van der Waals heterostructure. These results open up an appealing perspective to explore the nontrivial topology of Dirac nodal-line semimetal by devising the peculiar device geometry that allows for a novel roadmap to address targeted terahertz application requirements.

Doped Polyaniline/Graphene Composites for Photothermoelectric Detectors

“…, where k B is the Boltzmann constant, T is the temperature, and R refers to the device resistance. 35 By increasing the loading of graphene concentration from 5 to 30 wt %, the overall photoresponse rises from 1.0 to 2.5 V W −1 (Figure 4a). The NEP decreases to its lowest position in the 10 −10 range under the same measuring condition.…”

“…Due to the stable photoresistances, the prominent noise in such detectors is due to the fluctuation of carriers’ thermodynamic motion, also called the John–Nyquist noise. Therefore, NEP can be evaluated as follows: , where k B is the Boltzmann constant, T is the temperature, and R refers to the device resistance . By increasing the loading of graphene concentration from 5 to 30 wt %, the overall photoresponse rises from 1.0 to 2.5 V W –1 (Figure a).…”

Excitonic Insulator Enabled Ultrasensitive Terahertz Photodetection with Efficient Low‐Energy Photon Harvesting

“…Among them, the 1/ f noise is related to the change of electronic state, which usually occurs at low modulation frequency (below 1 kHz). [ 5 ] During our test, the modulation frequency is over 1 kHz, so it can be ignored in our system. Therefore, the main noise sources are v t and v b in our system, which originate from the thermal motion of carriers due to the nonzero ohmic resistance and the generation of carriers under bias voltage, [ 5 ] respectively.…”

“…[ 5 ] During our test, the modulation frequency is over 1 kHz, so it can be ignored in our system. Therefore, the main noise sources are v t and v b in our system, which originate from the thermal motion of carriers due to the nonzero ohmic resistance and the generation of carriers under bias voltage, [ 5 ] respectively. Inherently, the total noise current density can be obtained from the electrical characteristic of the detector by the formula i n = ( v t 2 + v b 2 ) 1/2 / r = (4 k B T / r + 2 qI DS ), [ 57 ] where k B is Boltzmann constant, T is the temperature, r is the resistance of the detector, q is elementary charge, and I DS is the dark current of the detector.…”

“…THz wave is located in the cross transition region of microwave electronics and infrared photonics, which promises it a wide range of applications, including security check, biomedical, wireless communication, and remote sensing. [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ] Current THz detectors based on different device structures and detection mechanisms of pyroelectric/Golay cells, [ 8 ] Schottky diode detectors, [ 9 ] quantum well detectors, [ 10 ] bolometers, [ 11 ] and field‐effect transistors detectors [ 12 ] suffer from some drawbacks, such as low sensitivity, complex material and device fabrication process, or low‐temperature dependence. [ 13 , 14 , 15 ] The main challenge and technical bottleneck of THz photodetection is the large mismatch between the nanoscale active region and the extremely long wavelength of the incident THz wave, resulting in low photoelectric conversion efficiency.…”