Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session H33: Plasmons and Photocurrets in 2D Materials |
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Sponsoring Units: DCMP Chair: Steven Bennett, Naval Research Laboratory Room: 296 |
Tuesday, March 14, 2017 2:30PM - 2:42PM |
H33.00001: Abstract Withdrawn
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Tuesday, March 14, 2017 2:42PM - 2:54PM |
H33.00002: Electrically-tunable exciton-plasmon coupling in van der Waals heterostructures You Zhou, Alexander High, Giovanni Scuri, Alan Dibos, Luis Jauregui, Kristiaan De Greve, Dominik Wild, Mikhail Lukin, Philip Kim, Hongkun Park Two dimensional transition metal dichalcogenide monolayers (TMDMs) are promising candidates for integrated optoelectronic devices. TMDMs can be stacked onto other van der Waals materials and the resulting heterostructures can be transferred onto various functional substrates. In addition, TMDMs exhibit tightly-bound, direct-gap excitons, which can be electrostatically controlled by applying a gate voltage. In this work, we employ such response to realize integrated on-chip optical modulators by coupling excitons in tungsten diselenide (WSe$_{\mathrm{2}})$ based van der Waals heterostructures to plasmonic waveguides fabricated on single crystalline silver. The enhanced light-matter interaction in the integrated nanoplasmonic waveguide-TMDM system allows us to realize high-performance non-resonant electro-optic switches that function both at 4 K and at room temperature. [Preview Abstract] |
Tuesday, March 14, 2017 2:54PM - 3:06PM |
H33.00003: Plasmon reflection by a narrow gap in a 2D conducting plane Bor-Yuan Jiang, Eugene Mele, Michael Fogler Graphene and other 2D conductors have recently attracted much interest in the context of controlled plasmon propagation and plasmonic circuits. This motivates us to study a prototypical plasmon reflector: a narrow strip of reduced local conductivity in an otherwise homogeneous conducting plane. The reflection coefficient of the plasmon is a function of two dimensionless parameters, the conductivity contrast and the gap width in units of the plasmon wavelength. Our analytical and numerical calculations show that the reflection coefficient possesses a sequence of high-transmission resonances of Fabry-Perot type as well as a low-transmission ``anti-resonance." In particular, the plasmon can be completely reflected by a gap of width much smaller than the plasmon wavelength because of the cancellation between the capacitive and inductive couplings of the two sides of the strip. [Preview Abstract] |
Tuesday, March 14, 2017 3:06PM - 3:18PM |
H33.00004: Controlling plasmon propagation in graphene using electrostatic local gates Sai S Sunku, Rebeca Ribeiro-Palau, Erik F Young, Loan T Le, Cory R Dean, Dimitri N Basov Compared to plasmons in traditional noble metals, plasmons in graphene have an inherent advantage in that they can be tuned by an external gate voltage. Several theoretical proposals have incorporated this idea to design electrostatic gates that produce a spatially inhomogeneous conductivity and allow unprecedented control over plasmon propagation. In this talk, we will present the fabrication of two such local gate structures. The first design aims to realize a tunable plasmonic reflector by using a metallic carbon nanotube as an ultranarrow gate. The second design consists of a pair of metal gates separated by a narrow slit, allowing the formation of a narrow p-n junction. Preliminary data from scanning near-field optical microscopy (SNOM) will also be presented. [Preview Abstract] |
Tuesday, March 14, 2017 3:18PM - 3:30PM |
H33.00005: Theory of interaction-induced renormalization of Drude weight and plasmon frequency in chiral multilayer graphene Wang-Kong Tse, Xiao Li We develop a theory for the optical conductivity of doped multilayer graphene including the effects of electron-electron interactions. Applying the quantum kinetic formalism, we formulate a set of pseudospin Bloch equations that governs the dynamics of the nonequilibrium density matrix driven by an external \emph{a.c.} electric field under the influence of Coulomb interactions. These equations reveal a dynamical mechanism that couples the Drude and interband responses arising from the chirality of pseudospin textures in multilayer graphene systems. We demonstrate that this results in an interaction-induced enhancement of the Drude weight and plasmon frequency strongly dependent on the pseudospin winding number. Using bilayer graphene as an example, we also study the influence of higher-energy bands and find that they contribute considerable renormalization effects not captured by a low-energy two-band description. We argue that this enhancement of Drude weight and plasmon frequency occurs generally in materials characterized by electronic chirality. [Preview Abstract] |
Tuesday, March 14, 2017 3:30PM - 3:42PM |
H33.00006: Quantum plasmonics through retarded Coulomb coupling to graphene electrons Andrii Iurov, Danhong Huang, Godfrey Gumbs, Wei Pan, Alexei Maradudin The retarded Coulomb couping of the surface plasmon mode to the collective excitation of Dirac electrons in a neighboring graphene monolayer is investigated and the characteristics of the resulting hybrid quantum- plasmon modes are discussed. The unique dispersion relations of these quantum-plasmon modes are expected to be experimentally observable. For double-layer graphene, the interplay between the interlayer Coulomb interaction and the retarded coupling of a surface plasmon mode to each sheet is obtained. As a significant correction to the static dielectric function of the host cladding layer on top of the conductor surface, the effective scattering matrix for coupled double-layer graphene and a thick conductor is obtained for constructing an effective-medium theory, which includes the role of both the Coulomb interaction between electrons in different graphene sheets and the retarded Coulomb coupling of these layers to the conductor. A scattering matrix can be employed for an effective-medium theory to calculate the optical properties of inserted conducting nanodots and nanorods between graphene and a conductor which can be applied to a super-resolution near-field imaging beyond the diffraction limit for functionalized biomolecules attached to these nanodots and nanorods. [Preview Abstract] |
Tuesday, March 14, 2017 3:42PM - 3:54PM |
H33.00007: Effects of the electron-plasmon interactions on the transport properties of a pristine graphene and a graphene coupled with Au nanoparticle arrays Wei Qin, Guanghui Chen, Laiming Wei, Changgan Zeng, Zhenyu Zhang Graphene has been revealed as an appealing material for designing two-dimensional electronic devices due to its inherently weak electron-phonon scattering and correspondingly large carrier mobility. In the high temperature regime, the phonon-limited resistivity depends linearly on the temperature. Here, we first study the effects of interactions between the conduction electrons and the intrinsic plasmon modes of a pristine graphene monolayer on the transport properties of graphene. Within Boltzmann transport theory, we find a nonlinear temperature-dependent correction to the linear dependence of the resistivity as a result of the electron-plasmon scattering. Next, we generalize to systems consisting of a monolayer graphene proximity coupled with Au nanoparticle arrays. In the regions covered by the Au nanoparticles, the electron-electron interactions are further altered by the presence of the nanocavity plasmon modes between the nanoparticles and graphene. We find that the relaxation time of the hybrid system is much longer than that of pristine graphene, leading to enhanced dephasing length of the conduction electrons. These findings are discussed in connection with our experimental observations. [Preview Abstract] |
Tuesday, March 14, 2017 3:54PM - 4:06PM |
H33.00008: Understanding Graphene-induced Large Shift of Surface Plasmon Resonance (SPR) of Au Films: The Challenge of Microscopic Modeling for Macroscopic Observation Kamrul Alam, Chao Niu, Yanan Wang, Wei Wang, Yang Li, Chong Dai, Xiaonan Shan, E.Joe Charlson, Xiang-Tian Kong, Yandi Hu, Alexey Belyanin, Gila Stein, Zhaoping Liu, Jonathan Hu, Zhiming Wang, Jiming Bao With the emergence of Graphene and other 2D materials, it was proposed that capping Au film with graphene could improve the performance of SPR based sensors due to enhanced local field and surface chemical adsorption. Such enhanced SPR sensitivity is further modelled and experimentally confirmed by many groups. However, the very SPR angle shift induced by 2D materials and its physics has been overlooked. We investigated the graphene induced SPR shifts in air by comparing experiment with modelling. A shift of 0.30$^{\mathrm{0}}$ is observed and it is 3 times larger than that from conventional modeling. We show steps to build more realistic model and evaluate the effect on SPR from surface morphologies of Au and graphene, anisotropy of graphene, and charge transfer between graphene and Au. This study illustrates the challenges in understanding the SPR of noble metal films modified by atomic scale materials and calls for more advanced and realistic modelling. [Preview Abstract] |
Tuesday, March 14, 2017 4:06PM - 4:18PM |
H33.00009: Photocurrent Switching of Monolayer MoS$_{\mathrm{2}}$ using Metal-Insulator Transition Jin Hee Lee, Hamza Zad Gul, Hyun Kim, Byoung Hee Moon, Subash Adhikari, Jung Ho Kim, Homin Choi, Young Hee Lee, Seong Chu Lim We achieve photocurrent switching of monolayer molybdenum disulfide (MoS$_{\mathrm{2}})$ by controlling the metal--insulator transition (MIT). N-type semiconducting MoS$_{\mathrm{2}}$ that is under a large negative gate bias, generates photocurrent by an optical excitation that is attributed to the increase of excess carriers in the conduction band. However, under a large positive gate bias that causes a phase shift from the semiconducting to a metallic MoS$_{\mathrm{2}}$ the photocurrent by excess carriers in the conduction band by the laser disappears by enhanced electron--electron scattering. Thus, no photocurrent is detected in metallic MoS$_{\mathrm{2}}$ Our results indicate that the photocurrent of MoS$_{\mathrm{2}}$ can be switched by MIT transition that is controllable using the gate bias. [Preview Abstract] |
Tuesday, March 14, 2017 4:18PM - 4:30PM |
H33.00010: Electrical and Photoconductivity study on few layers ReSe$_{\mathrm{2}}$ Nihar Pradhan, Carlos Garcia, Bridget Isenberg, Daniel Rhodes, Shahriar Memaran, Joshua Holleman, Stephen McGill, Luis Balicas Transition metal dichalcogenides (TMDs) have emerged as attractive materials for electronic and optoelectronic device applications due to their tunable band gap as a function of layers and easier to produce single atomic layer form, which could be potential pathways beyond CMOS technologies. Among the TMDs semiconductors, extensive research has been conducted on few compounds such as MoS$_{\mathrm{2}}$, WS$_{\mathrm{2}}$, and WSe$_{\mathrm{2}}$ focusing on electrical and optical properties of single-to-few atomic layers. These compounds show direct band gap transition when exfoliated to single layer from bulk crystals. However, there are other layered materials such as ReS$_{\mathrm{2}}$, ReSe$_{\mathrm{2}}$, InSe, etc. are recently reported displays direct band gap irrespective to the number of layers, makes promising application in optoelectronics. Here, we present an intrinsic electrical and photoconductivity study on less studied ReSe$_{\mathrm{2}}$ compound, mechanically exfoliated on to the Si/SiO$_{\mathrm{2}}$ substrate. The field-effect mobility at room temperature of few-layered ReSe$_{\mathrm{2}}$ device is \textasciitilde 10cm$^{\mathrm{2}}$/Vs. Hopefully we will also present the detail electrical transport properties of ReSe$_{\mathrm{2}}$ field-effect transistors as a function of temperature. [Preview Abstract] |
Tuesday, March 14, 2017 4:30PM - 4:42PM |
H33.00011: Temperature Dependent Photocurrent Spectroscopy of Few Layer CuIn$_{\mathrm{7}}$Se$_{\mathrm{11}}$ Milinda Wasala, Prasanna Patil, Sujoy Ghosh, Sidong Lei, Robert Vajtai, Pulickel Ajayan, Saikat Talapatra Group III-VI based 2D semiconductor, due to their exotic optical properties, could possibly lead to multifunctional opto-electronic applications such as tunable photo detectors. Here, we report on the detailed study on temperature dependent photocurrent spectroscopy of few layer CuIn$_{\mathrm{7}}$Se$_{\mathrm{11}}$, mechanically exfoliated from crystals grown using chemical vapor transport technique. CuIn$_{\mathrm{7}}$Se$_{\mathrm{11}}$ photocurrent spectra reveals the information about the direct band gap, indirect band gap as well as the band gap variation with the temperature. Further, the gate voltage can be used to tune the wavelength dependent photoresponse nature of these materials. These key findings and comparative analysis of group III-VI based photo detectors will be discussed. [Preview Abstract] |
Tuesday, March 14, 2017 4:42PM - 4:54PM |
H33.00012: Three-body Annihilation at the Onset of Anomalous Photocurrent Suppression in Vertical Heterostrucutres of MoTe$_2$ Trevor Arp, Dennis Pleskot, Nathaniel Gabor We have developed a new photoresponse imaging technique that utilizes extensive data acquisition over a large parameter space. By acquiring a multi-dimensional data set, we fully capture the intrinsic optoelectronic response of two-dimensional heterostructure devices. Using this technique we have investigated the behavior of heterostructures consisting of molybdenum ditelluride (MoTe$_{2}$) sandwiched between graphene top and bottom contacts. Under near-infrared optical excitation, the ultra-thin heterostructure devices exhibit sub-linear photocurrent response that recovers within several dozen picoseconds. As the optical power increases, the dynamics of the photoresponse, consistent with 3-body annihilation, precede a sudden suppression of photocurrent. The observed dynamics near the threshold to photocurrent suppression may indicate the onset to a strongly interacting population of electrons and holes. [Preview Abstract] |
Tuesday, March 14, 2017 4:54PM - 5:06PM |
H33.00013: A giant enhancement of multiphoton absorption in single-layer molybdenum disulfide Feng Zhou, Wei Ji Identifying light absorption mechanisms in nanoscale materials, which are more efficient than those observed in bulk semiconductors, are of paramount importance to next-generation, infrared photo-detection. Here, we report considerable enhancement of degenerate two-photon absorption (2PA) and three-photon absorption (3PA) through two-dimensional (2D) excitonic effects in single-layer molybdenum disulfide (1L-MoS$_{\mathrm{2}})$. We theoretically predict that both degenerate 2PA and 3PA coefficients of 1L-MoS$_{\mathrm{2}}$ are enhanced by 10-1000 times in the near-infrared (NIR), as compared with those of bulk semiconductors. Our theoretical prediction is validated by measuring photocurrents induced by 2PA or 3PA in a 1L-MoS$_{\mathrm{2}}$ photo-detector at room temperature where excitons in the immediate vicinity of the bandgap are transferred to the conduction band by a very small amount of thermal energy and dissociated under an external electric field. Our finding lays theoretical foundation and provides experimental evidence for developing sensitive infrared multiphoton detectors for nano-photonics. [Preview Abstract] |
Tuesday, March 14, 2017 5:06PM - 5:18PM |
H33.00014: Electronic and optoelectronic device applications based on ReS$_{2}$ Erfu Liu, Mingsheng Long, Yaojia Wang, Yiming Pan, Chinghwa Ho, Baigeng Wang, Feng Miao Rhenium disulfide (ReS$_{2})$ is a unique semiconducting TMD with distorted 1T structure and weak interlayer coupling. We have previously investigated its in-plane anisotropic property and electronic applications on FET and digital inverters [1]. In this talk, we will present high responsivity phototransistors based on few-layer ReS$_{2}$. Depending on the back gate voltage, source drain bias and incident optical light intensity, the maximum attainable photoresponsivity can reach as high as 88,600 A W$^{-1}$, which is one of the highest value among individual two-dimensional materials with similar device structures. Such high photoresponsivity is attributed to the increased light absorption as well as the gain enhancement due to the existence of trap states in the few-layer ReS$_{2}$ flakes. The existence of trap states is proved by temperature dependent transport measurements. It further enables the detection of weak signals [2]. Our studies underscore ReS$_{2}$ as a promising material for future electronic and sensitive optoelectronic applications. References:[1] Erfu Liu, et al. Nature communications 6, 6991(2015). [2] Erfu Liu, et al. Advanced Functional Materials 26, 1938 (2016) [Preview Abstract] |
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