Dielectric Contrast Tailoring for Polarized Photosensitivity toward Multiplexing Optical Communications and Dynamic Encrypt Technology

Abstract

A selective-area oxidation strategy is developed to polarize high-symmetry 2D layered materials (2DLMs). The dichroic ratio of the derived O-WS2/WS2 photodetector reaches ∼8, which is competitive among state-of-the-art polarization photodetectors. Finite-different time-domain simulations consolidate that the polarization-sensitive photoresponse is associated with anisotropic spacial confinement, which gives rise to distinct dielectric contrasts for linearly polarized light of various directions and thus the polarization-dependent near-field distribution. Furthermore, selective-area oxidation treatment brings about dual effects, comprising the in situ formation of seamless in-plane WS2 homojunctions by thickness tailoring and the formation of out-of-plane O-WS2/WS2 heterojunctions. As a consequence, the recombination of photocarriers is markedly suppressed, resulting in outstanding photosensitivity with the optimized responsivity, external quantum efficiency, and detectivity of 0.161 A/W, 49.4%, and 1.4 × 1011 Jones for an O-WS2/WS2 photodetector in a self-powered mode. A scheme of multiplexing optical communications is revealed by harnessing the intensity and polarization state of light as independent transmission channels. Furthermore, dynamic encryption by leveraging the polarization state as a secret key is proposed. In the end, broad universality is reinforced through the induction of linear dichroism within 2D WSe2 crystals. On the whole, this study provides an additional perspective on polarization optoelectronics based on 2DLMs.

Multilayer SnS2/few-layer MoS2 heterojunctions with in-situ floating photogate toward high-performance photodetectors and optical imaging application

“…As shown in Fig. 4d-i, for all the three devices, both responsivity and detectivity decrease with increasing light intensity, which are consistent with previous studies on 2DLMsbased photodetectors [72,73]. Basically, as the incident photons increase, more photocarriers are generated and the occupied trap states increase.…”

Ultrabroadband Imaging Based on Wafer‐Scale Tellurene

“…On one hand, linear dichroism can be introduced through extrinsic symmetry engineering such as strain modulation [63][64][65] and dielectric contrast tailoring. [66] On the other hand, the anisotropy of tellurene can be restored by oriented growth of tellurene. [67] As for the further improvement of photosensitivity, taking advantage of the excellent compatibility of the room-temperature growth, several improvement strategies with broad universality, such as the integration of optical waveguides/cavities/ light-trapping structures, [68][69][70] dielectric engineering, [71] modification of optical antennas, [72] defect engineering, [73] selected-area electrostatic gating, [57] contact engineering, [74] etc., can theoretically be exploited to enhance the light-tellurene interactions, promote the exciton dissociation, and prolong the carrier lifetime.…”

Advances in Flexible Organic Photodetectors: Materials and Applications

“…Among these two-dimensional semiconductors are layered MoS 2 , WS 2 , MoSe 2 , InSe, black phosphorous, SnS 2 , SnSe 2 , and GaSe, which are being investigated extensively for optoelectronics as they exhibit high absorption coefficients and tunable properties. Among these layered materials, SnSe 2 is a potential candidate for optoelectronic applications owing to its high intrinsic absorption coefficient [ 148 ] and being an earth-abundant and environmentally benign compound. SnSe 2 exhibits a hexagonal CdI 2 crystal structure with n-type conductivity and a direct bandgap of around 1.2 eV.…”