Low‐Dimensional‐Materials‐Based Photodetectors for Next‐Generation Polarized Detection and Imaging

Abstract

The vector characteristics of light and the vectorial transformations during its transmission lay a foundation for polarized photodetection of objects, which broadens the applications of related detectors in complex environments. With the breakthrough of low‐dimensional materials (LDMs) in optics and electronics over the past few years, the combination of these novel LDMs and traditional working modes is expected to bring new development opportunities in this field. Here, we mainly focus on the state‐of‐the‐art progress of LDMs as polarization‐sensitive components in polarized photodetection and even the imaging, with emphasis on the relationship between traditional working principle of polarized photodetectors (PPs) and photoresponse mechanisms of LDMs. Particularly, from the view of constitutive equation, the existing works are reorganized, reclassified and reviewed. The perspectives on the opportunities and challenges are also discussed. We hope that this work can provide a more general overview in the use of LDMs in this field, sorting out the way of related devices for “more than Moore” or even the “beyond Moore” research.This article is protected by copyright. All rights reserved

Polarization-Sensitive Self-Powered Schottky Photodetector with High Photovoltaic Performance Induced by Geometry-Asymmetric Contacts

“…Meanwhile, the difference in the work function between Au and ReSe 2 denoted by the average Fermi level difference (ΔE f ) can be calculated by the equation ΔE f = W Au − W ReSed 2 = eSPD ReSed 2 − eSPD Au . 2 According to the Gaussian distributions from the corresponding regions of Figure 2b,e, the built-in electric fields in region A 1 and region B 1 are measured to be about 15 and 53 meV, respectively. Besides, as shown in Figure S4c,d, the built-in electric fields in region A 2 and region B 2 are measured to be about 19 and 59 meV, respectively.…”

“…Intuitively, the photocurrent signals originate from the whole region B rather than region A, which reveals that region B with a bigger surface potential mainly contributes to the generation of photocurrent, further confirming the influence of the difference in the Schottky barrier height. In the meanwhile, the photoactive area of region B is about 16.07 μm 2 . In general, short-circuit current (I SC ) and open-circuit voltage (V OC ) in the asymmetric Schottky photodetector can be obtained with the equations 27 where J SC is the short-circuit current density and W S/D and t S/D represent the widths and the thicknesses at region A or region B near the channel, respectively.…”

“…Similarly, the W ReSe 2 is smaller than the W Au in region B 2 and region A 2 . Meanwhile, the difference in the work function between Au and ReSe 2 denoted by the average Fermi level difference (Δ E f ) can be calculated by the equation Δ E f = W Au – W ReSe 2 = eSPD ReSe 2 – eSPD Au . According to the Gaussian distributions from the corresponding regions of Figure b,e, the built-in electric fields in region A 1 and region B 1 are measured to be about 15 and 53 meV, respectively.…”

“…Polarization-sensitive photodetection plays an important part in both military and civilian fields including optical fiber communication, environmental monitoring, and remote imaging. − For decades, commercial polarization-sensitive photodetectors have been established on hybrid systems composed of bulky polarized optical components and detector units and arrays. However, such systems inevitably face many issues, including large volume, high cost, and processing difficulty, which still need to be resolved. − In recent years, benefiting from the advantages of in-plane anisotropy, high optical absorption coefficient, and thickness-dependent band gap, low-symmetry two-dimensional (2D) materials have been proven to be promising candidates for high-performance self-powered photodetectors. − In particular, 2D ReSe 2 has an indirect band gap of 1.2–1 3 eV.…”

“…. 10,73 Remarkably, the Raman intensity can be well-fitted by the equation I = μ 2 cos(θ + φ) 2 + ω 2 sin(θ + φ) 2 + ν 2 2ν(μ + ω)sin(θ + φ)cos(θ + φ), where θ and φ are the rotation angle and the angle between the AC and the defined 0°, respectively. 10 Obviously, as shown in Figure 5b,c, the maximum and minimum values of polarization Raman intensity for the inplane A g modes (118 and 283 cm −1 ) are 60°(240°) and 150°( 330°), respectively, which can be used to determine the armchair (AC) and zigzag (ZZ) directions of the multilayered ReSe 2 nanosheet in device#1.…”