A Wide‐Range Photosensitive Weyl Semimetal Single Crystal—TaAs

et al. 2020

Adv Elect Materials

Infrared (IR) photodetectors are essential for optical communication, imaging, and medical and environmental monitoring technologies. However, current IR photodetectors relying on conventional narrow‐gap semiconductors require strict lattice match epitaxy and expensive manufacturing methods, and the incompatibility with complementary metal‐oxide‐semiconductor technique cannot meet the requirement of high integration and miniaturization. Here, the controllable growth of an ultrathin narrow‐gap semiconductor Cr2S3, with thickness down to unitcell of ≈1.85 nm, is reported using chemical vapor deposition method. The as‐grown 2D Cr2S3 exhibits outstanding environmental stability with negligible degradation even after exposure in air for more than two months. By combining the optics Fourier transfer infrared spectrometer with density functional theory calculations, the bandgap of the synthesized Cr2S3 nanoflakes is determined to be 0.15 eV. A photodetector based on the 2D Cr2S3 exhibits a high responsivity (14.4 A W−1 at 520 nm, 6.0 A W−1 at 808 nm, and 3.0 A W−1 at 1550 nm) and excellent detectivity (4.0 × 1010 Jones at 520 nm, 1.7 × 1010 Jones at 808 nm, and 8.3 × 109 Jones at 1550 nm) under ambient conditions. These findings indicate that the air‐stable 2D narrow‐gap semiconductor Cr2S3 can act as a highly competitive candidate for broadband photodetector application and fundamental photophysics investigation.

Section: Figurementioning

confidence: 95%

An Atomically Thin Air‐Stable Narrow‐Gap Semiconductor Cr₂S₃ for Broadband Photodetection with High Responsivity

Xie

et al. 2020

Adv Elect Materials

“…One of the main factors that hinders the development of photonics and optoelectronics is the lack of materials with broad‐band optical response and strong light–matter interaction. Therefore, it is an urgent need and many efforts have been devoted to searching for this kind of novel materials …”

Section: Introductionmentioning

confidence: 99%

Two‐Dimensional GeP‐Based Broad‐Band Optical Switches and Photodetectors

Nie

Advanced Optical Materials

et al. 2019

photonics and optoelectronics is the lack of materials with broad-band optical response and strong light-matter interaction. Therefore, it is an urgent need and many efforts have been devoted to searching for this kind of novel materials. [2][3][4][5] The broad-band optical response of 2D nanomaterial is related to the unique band structure and electronic properties. [1] Graphene exhibits a wide-spectral photonic response from ultraviolet to the radio-wave regimes owing to its gapless and conical-shape band structure. However, lack of intrinsic bandgap makes graphene-based devices suffer from relatively small on/off ratio, large dark current, and poor photo response. The relative low absorption and high non-saturable loss of graphene in optical response limit its extensive applications. [6][7][8][9] Following graphene, the most studied 2D transition metal dichalcogenides (TMDCs) possess a bandgap ranging from 1.0 to 2.0 eV, indicating their practical optoelectronic applications are not available in midinfrared (MIR) wavelength range. [10,11] After graphene and TMDCs, black phosphorus (BP), the most thermodynamically stable allotrope of phosphorus, has been thoroughly studied as a novel 2D layered material since early 2014. [12] It has triggered significant interests in both scientific research and potential electronic, optoelectronic, and biomedicine applications because of its unique and exotic properties. [13][14][15] Layered BP has a direct bandgap with layer-dependent variation over ≈0.3-2.0 eV, which gives rise to broad-band optical properties from visible to MIR region. The intrinsic layer-dependent direct bandgap gives rise to high on/off ratio and low dark current for electronic devices and makes BP an appropriate 2D material for MIR photonic applications. Moreover, the bandgap of BP can be efficiently tuned by electrical gating, which should pave the way for optoelectronic devices. [16] BP presents puckered structure with in-plane anisotropy, which results in specific dichroic optical properties of light absorption and photoluminescence. [17] However, easy oxidation under ambient environment is the biggest obstacle that significantly impedes its practical applications. [14,[18][19][20][21][22] Therefore, how to improve the long-term stability of BP has become a challenge.Germanium phosphide (GeP), a typical 2D group IV-V semiconductor, has attracted significant attention due to the advantages of higher thermodynamic stability than black phosphorus (BP), widely tunable bandgap, high carrier mobility, and in-plane anisotropy. However, its photonic and optoelectronic properties have not been extensively explored so far. Herein, large size and high-quality GeP single bulk crystal is successfully grown by flux method and stripped into 2D nanosheets with liquid phase exfoliation (LPE) and spin-coating methods. The broad-band photonic and optoelectronic properties of 2D GeP nanosheets are systematically investigated. First principles calculations are performed to verify its widely tunable bandgap from 0.43 eV f...

“…Over the past few years, topological insulator and Dirac semi‐metal material have risen a great interest in quantum physics research . These emerging materials have remarkable potential for LIR detection due to its distinct electronic structure . Such novel materials also need to combine with other materials to promote entire performance .…”

Section: Recent Design Strategies For 2d‐based Photodetectorsmentioning

confidence: 99%

“…[90][91][92][93][94] These emerging materials have remarkable potential for LIR detection due to its distinct electronic structure. [95][96][97] Such novel materials also need to combine with other materials to promote entire performance. 39,73,98,99 Qiao et al incorporated a similar hexagonal symmetry Bi 2 Te 3 with graphene as shown in Figure 5G, the photodetector demonstrated a strong and broadband responsivity reach telecommunication band (35 A/W and extend to 1550 nm depicted in Figure 5H).…”

Section: Single Layer Enhanced Photoconductorsmentioning

confidence: 99%

Design strategies for two‐dimensional material photodetectors to enhance device performance

Han

Chen

et al. 2019

InfoMat

200

143

Two‐dimensional (2D) materials are intensively attractive for fabricating high sensitive photodetectors in terms of atomically thin flexible and ultrafast charge transport feature. Due to their atomically thin body, designing high performance detector requires new physical mechanisms and device structures. In this review, we classify design strategies and device structures into four categories depending on their physical mechanisms (photovoltaic effect, photoconductive effect, photothermoelectric effect or photobolometric effect, and surface plasma‐ wave‐assisted effect), and summarize the device performances. Finally, future prospects and development direction for 2D material photodetectors are described. Those design strategies descriptions about photoelectronic detector provide a reference for high responsivity and fast response speed photodetector at broadband sensing in the future.