Abstract-Distinctive Performance of Terahertz Photodetection Driven by Charge‐Density‐Wave Order in CVD‐Grown Tantalum Diselenide

Lin Wang,  Jin Wang,  Changlong Liu,   Huang Xu,  Ang Li,  Dacheng Wei,   Yunqi Liu,  Gang Chen,  Xiaoshuang Chen,  Wei Lu,

https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.201905057?af=R

The quantum behavior of carriers in solid is the foundation of modern electronic and optoelectronic technology, but it is still facing huge challenges within inherited single‐particle quantum processes working at the millimeter wave/terahertz (THz) band. Here, a straightforward strategy for the direct detection of millimeter wave/THz photons in a sub‐wavelength metal‐TaSe2‐metal structure under strong interaction with a localized field of surface plasmon is proposed. By breaking the inversion symmetry under the perturbations of electric field and atomic reconstruction from van der Waals integration, the nonequilibrium electronic states under a radiant field can be manipulated in a collective fashion, leading to a large photocurrent responsivity over 40 A W−1 and noise equivalent power less than 1 pW Hz−1/2 even at room temperature. A more than 40‐fold enhancement in responsivity is achieved when transitioning from the normal phase to the CDW phase. The findings shed fresh light on the understanding of the delicate balance in the charge‐ordered phase, and facilitate the exploitation of a correlated electron system for optoelectronic applications in fields of security, remote sensing, and imaging.

Abstract-Ultrasensitive Room‐Temperature Terahertz Direct Detection Based on a Bismuth Selenide Topological Insulator

Weiwei Tang,   Antonio Politano,  Cheng Guo,   Wanlong,  Guo,   Changlong Liu,   Lin Wang,  Xiaoshuang Chen,  Wei Lu,

https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.201801786

Despite their huge application capabilities, millimeter‐ and terahertz‐wave photodetectors still face challenges in the detection scheme. Topological insulators (TIs) are predicted to be promising candidates for long‐wavelength photodetection, due to the presence of Dirac fermions in their topologically protected surface states. However, photodetection based on TIs is usually hindered by the large dark current, originating from the mixing of bulk states with topological surface states (TSSs) in most realistic samples of TIs. Here millimeter and terahertz detectors based on a subwavelength metal–TI–metal (MTM) heterostructure are demonstrated. The achieved photoresponse stems from the asymmetric scattering of TSS, driven by the localized surface plasmon‐induced terahertz field, which ultimately produces direct photocarriers beyond the interband limit. The device enables high responsivity in both the self‐powered and bias modes even at room temperature. The achieved responsivity is over 75 A/W, with response time shorter than 60 ms in the self‐powered mode. Remarkably, the responsivity increases by several orders of magnitude in the biased configuration, with the noise‐equivalent power (NEP) of 3.6 × 10−13 W Hz−1/2 and a detectivity of 2.17 × 1011cm Hz−1/2 W−1 at room temperature. The detection performances open a way toward realistic exploitation of TIs for large‐area, real‐time imaging within long‐wavelength optoelectronics.

Abstract-Black-Phosphorus Terahertz Photodetectors

Leonardo Viti, Jin Hu, Dominique Coquillat, Wojciech Knap, Alessandro Tredicucci, Antonio Politano, Miriam Serena Vitiello

https://arxiv.org/abs/1805.00735

The discovery of graphene and the related fascinating capabilities have triggered an unprecedented interest in inorganic two-dimensional (2D) materials. Despite the impressive impact in a variety of photonic applications, the absence of energy gap has hampered its broader applicability in many optoelectronic devices. The recent advance of novel 2D materials, such as transition-metal dichalcogenides or atomically thin elemental materials, (e.g. silicene, germanene and phosphorene) promises a revolutionary step-change. Here we devise the first room-temperature Terahertz (THz) frequency detector exploiting few-layer phosphorene, e.g., a 10 nm thick flake of exfoliated crystalline black phosphorus (BP), as active channel of a field-effect transistor (FET). By exploiting the direct band gap of BP to fully switch between insulating and conducting states and by engineering proper antennas for efficient light harvesting, we reach detection performance comparable with commercial detection technologies, providing the first technological demonstration of a phosphorus-based active THz device.

Abstract-Uncooled EuSbTe3 photodetector highly sensitive from ultraviolet to terahertz frequencies

Biao Wang, Dong Wu, Hai Zhu, Huibin Zhou, Jian Wei, Nan Lin Wang, Jiasen Niu, Ping Zheng, Yingxin Wang, Yingying Niu, Yu Quan Su, Ziran Zhao

http://iopscience.iop.org/article/10.1088/2053-1583/aa939c/pdf

Light probe from Uv to THz is critical in photoelectronics and has great applications ranging from imaging, communication to medicine. However, the room temperature ultrabroadband photodetection across visible down to far-infrared is still challenging. The challenging arises mainly from the lack of suitable photoactive materials. Because that conventional semiconductors, such as silicon, have their photosensitive properties cut off by the bandgap and are transparent to spectrum at long-wavelength infrared side. Comparatively, the dielectrics with very narrow band-gap but maintain the semiconductor-like electrical conduction would have priorities for ultrabroadband photodetection. Here we report on EuSbTe3 is highly sensitive from ultraviolet directly to terahertz (THz) at room temperature. High photoresponsivities 1 ~ 8 A W-1 reached in our prototype EuSbTe3 detectors with low noise equivalent power (NEP) recorded, for instances ~ 150 pW  Hz-1/2 (at λ = 532 nm) and ~0.6 nW  Hz-1/2 (at λ = 118.8 µm) respectively. Our results demonstrate a promising system with direct photosensitivity extending well into THz regime at room temperature, shed new light on exploring more sophisticated multi-band photoelectronics

Abstract-Heterostructured hBN-BP-hBN Nanodetectors at Terahertz Frequencies

http://onlinelibrary.wiley.com/doi/10.1002/adma.201601736/abstract

By reassembling the thin isolated atomic planes of hexagonal borum nitride (hBN) with a few layer phosphorene (black phosphorus BP), hBN/BP/hBN heterostructures were mechanically stacked to devise high efficiency THz photodetectors operating in the 0.3–0.65 THz range, from 4K to 300K, with a record signal-to-noise ratio of 20000.

Abstract-Terahertz photodetector based on double-walled carbon nanotube macrobundle–metal contacts

Yingxin Wang, Xiangquan Deng, Guowei Zhang, Jinquan Wei, Jia-Lin Zhu, Zhiqiang Chen, Ziran Zhao, and Jia-Lin Sun
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-23-10-13348

We report on the characterization of a terahertz (THz) photodetector with an extremely simple structure consisting of only a macroscopic bundle of double-walled carbon nanotubes (DWCNTs) suspended between two metal electrodes. Polarization-sensitive, broadband, and significant photoresponse occurring at the DWCNT–metal contacts under THz illumination are observed with room-temperature photocurrent and photovoltage responsivities up to ∼16 mA/W and ∼0.2 V/W at 2.52 THz, respectively. Scanning photocurrent measurements provide evidence that the photothermoelectric mechanism dominates the detector response. The simple geometry and compact nature of our device make it suitable for integration and show promising applications for THz detection.

© 2015 Optical Society of America

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Abstract-Terahertz photodetectors based on tapered semiconductor nanowires

L. Romeo¹, D. Coquillat², E. Husanu¹, D. Ercolani¹, A. Tredicucci³, F. Beltram¹, L. Sorba¹, W. Knap² and M. S. Vitiello^1,a)
 HIDE AFFILIATIONS
1 NEST, Scuola Normale Superiore and CNR—Istituto Nanoscienze, Piazza San Silvestro 12, I-56127 Pisa, Italy
2 Laboratoire Charles Coulomb, UMR 5221 CNRS-Universite' Montpellier 2, 34095 Montpellier, France
3 Dipartimento di Fisica, Università di Pisa, Largo Pontecorvo 3 and NEST, CNR - Istituto Nanoscienze, 56127 Pisa, Italy
a) miriam.vitiello@sns.it
Appl. Phys. Lett. 105, 231112 (2014); http://dx.doi.org/10.1063/1.4903473

http://scitation.aip.org/content/aip/journal/apl/105/23/10.1063/1.4903473?showFTTab=true&containerItemId=content/aip/journal/apl

We report on the demonstration of Terahertz (THz) broadband detectors based on field effect transistors exploiting tapered semiconductor nanowires. The intrinsic asymmetry provided by the nanowires geometry allows to achieve responsivity values as high as 55 V/W (2.5 mA/W) and a noise-equivalent-power of 3 × 10⁻¹⁰ W/Hz^1/2 independent of the specific gate voltage applied. The possibility to reduce the number of terminals required to the source and drain contacts only and the technological feasibility of multi-pixel arrays are promising for the realization of compact and integrated THz matrix array detection systems.