Optical second harmonic generation in encapsulated single-layer InSe

Leisgang, Nadine; Roch, Jonas G.; Froehlicher, Guillaume; Hamer, Matthew J.; Terry, Daniel J.; Gorbachev, Roman; Warburton, Richard J.

doi:10.1063/1.5052417

Cited by 30 publications

(18 citation statements)

References 22 publications

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“…The angular dependence of the SHG response that can be measured, for example, by rotating the crystal, and measuring the SHG polarization and intensity can provide important information on 2D materials anisotropy. [ 244,252,253 ] Considering normal incidence geometry, the angular dependent SHG susceptibilities for the point group C 2 ν and D 3h had been calculated. The corresponding angulardependent polar plots of SHG are shown in Figure 20d–f, together with the corresponding frequency of the excitation field, ω and the maximum χ (2) values.…”

Section: Applications: Theory and Experiments Prospectmentioning

confidence: 99%

Recent Advances in 2D Metal Monochalcogenides

Sarkar

Stratakis

2020

Advanced Science

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The family of emerging low‐symmetry and structural in‐plane anisotropic two‐dimensional (2D) materials has been expanding rapidly in recent years. As an important emerging anisotropic 2D material, the black phosphorene analog group IV A –VI metal monochalcogenides (MMCs) have been surged recently due to their distinctive crystalline symmetries, exotic in‐plane anisotropic electronic and optical response, earth abundance, and environmentally friendly characteristics. In this article, the recent research advancements in the field of anisotropic 2D MMCs are reviewed. At first, the unique wavy crystal structures together with the optical and electronic properties of such materials are discussed. The Review continues with the various methods adopted for the synthesis of layered MMCs including micromechanical and liquid phase exfoliation as well as physical vapor deposition. The last part of the article focuses on the application of the structural anisotropic response of 2D MMCs in field effect transistors, photovoltaic cells nonlinear optics, and valleytronic devices. Besides presenting the significant research in the field of this emerging class of 2D materials, this Review also delineates the existing limitations and discusses emerging possibilities and future prospects.

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Section: Applications: Theory and Experiments Prospectmentioning

confidence: 99%

Recent Advances in 2D Metal Monochalcogenides

Sarkar

Stratakis

2020

Advanced Science

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“…The integrated intensities of the experimentally measured SHG were used to calculate the magnitudes of the pervolume second-order susceptibility c (2) for these systems, as ranked among other systems in the NIR/Vis in Figure 1c. 8,13,16,[19][20][21][22][23] . When comparing to other 2D materials, only values calculated by modeling the system as a polarizable sheet were used, since previous assumptions of a bulk model for monolayer MoS2 have resulted in a 900× overestimate of its c (2) .…”

Section: Main Textmentioning

confidence: 99%

Unexpected Near-Infrared to Visible Nonlinear Optical Properties from 2-D Polar Metals

et al. 2020

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Nonlinear frequency mixing (e.g. harmonic generation) and polarization rotation of electromagnetic waves are the foundation of many important and emergent applications, including laser technologies, optical switches, and frequency combs, among others. 1 The current state-ofthe-art for second-order harmonic generation is achieved using a sequence of multiple quantum wells that are designed to enhance transitions resonantly at both fundamental and harmonic frequencies. 2 However, these systems are intrinsically limited to the mid infrared, precluding their operation at frequencies relevant for optical imaging and telecommunications. Therefore, new materials that can achieve large nonlinear optical responses over a broader range of frequencies are needed. Here, we describe near-infrared-to-visible second harmonic generation for two-

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“…Few-layer InSe (γ-phase) belongs to point group C3v, while monolayer InSe belongs to point group D3h with additional zz  mirror symmetry. The broken inversion symmetry gives rise to high nonlinearities as in the optical second harmonic generation of monolayer and few-layer InSe [73][74][75] .…”

Section: Crystal Structure and Raman Scatteringmentioning

confidence: 99%

The optical properties of few-layer InSe

Song

Huang

Wang

et al. 2020

Journal of Applied Physics

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Few-layer InSe draws tremendous research interests owing to the superior electronic and optical properties. It exhibits high carrier mobility up to more than 1000 cm 2 /Vs at room temperature. The strongly layer-tunable band gap spans a large spectral range from near-infrared to the visible. In this perspective, we systematically review the optical properties of few-layer InSe. Firstly, the intrinsic optical and electronic properties are introduced. Compared to other two-dimensional (2D) materials, the light-matter interaction of few-layer InSe is unusual. The band gap transition is inactive or extremely weak for in-plane polarized light, and the emission light is mainly polarized along the out-of-plane direction. Secondly, we will present several schemes to tune the optical properties of few-layer InSe such as external strain, surface chemical doping and van der Waals (vdW) interfacing.Thirdly, we survey the applications of few-layer InSe in photodetection and heterostructures.Overall, few-layer InSe exhibits great potential not only in fundamental research, but also in electronic and optoelectronic applications. / 42Furthermore, the applications of few-layer InSe in optoelectronics will be discussed in section Ⅳ.Finally, we present an outlook on the future study of the optical properties in section Ⅴ. II. The intrinsic optical and electronic properties of few-layer InSe A. Layer-dependent band structuresThe band structures of 2D materials can exhibit strong layer dependence due to the quantum confinement in the out-of-plane direction. For instance, there exists an indirect-to-direct bandgap transition for the TMDCs with thickness decreasing from bilayer to monolayer 18,19 . Another wellknown example is BP, possessing largely layer-tunable direct bandgap from the visible (the optical band gap is 1.73 eV for monolayer) to mid-infrared range (0.35 eV for bulk) [30][31][32][33] . The band structures of few-layer InSe can be largely modified by changing the layer number according to the DFT and/or tight binding (TB) calculations [40][41][42][43][44][45][46][47] (for a book see 48 ) as well as PL experiments 34,35,[49][50][51][52][53][54] . Fig. 1(a) shows the DFT band structure of monolayer InSe 43 . There are two interband transitions near the Γ point in Brillouin zone in which we are interested. One is the band gap transition between the valence band maximum (Se-pz orbital dominated) and the conduction band minimum (In-s orbital dominated), marked as transition-A. Another one is the interband transition between the deeper valence bands (degenerate Se-px/y orbitals dominated) and the conduction band (In-s orbital dominated), which is labeled as transition-B. For few-layer InSe, the valence/conduction band splits into subbands due to the interlayer interactions, resulting in a reduced band gap. Bandurin et al.systematically performed PL measurements on monolayer and few-layer InSe encapsulated by hexagonal boron nitride (hBN) 35 . Note that the PL peak is originated from the light emission of excitons, whose energy ...

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Optical second harmonic generation in encapsulated single-layer InSe

Cited by 30 publications

References 22 publications

Recent Advances in 2D Metal Monochalcogenides

Recent Advances in 2D Metal Monochalcogenides

Unexpected Near-Infrared to Visible Nonlinear Optical Properties from 2-D Polar Metals

The optical properties of few-layer InSe

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