Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session M21: Photocurrents in 2D Materials |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Romina Yalovetzky, JPMorgan Chase Room: Room 213 |
Wednesday, March 8, 2023 8:00AM - 8:12AM |
M21.00001: High-performing BP/MoTe2 mid-infrared photodetectors integrated with silicon waveguides Po-Liang Chen, Tian-Yun Chang, Jia-Xin Li, Wei-Qing Li, Chang-Hua Liu, Yueyang Chen, Arka Majumdar Developing high-performing and silicon compatible mid-infrared photodetectors will greatly benefit mid-infrared silicon photonics, useful to chemical sensing and medical diagnostics applications. But currently, it remains challenging to integrate mid-IR optoelectronics, such as II−VI or III−V semiconductors, with silicon photonics due to the mismatched lattice constant. To this regard, using the emerging two-dimensional (2D) materials has been considered as an alternative approach, as they could offer a wide variety of band gaps and can be assembled with each other to form van der Waals heterostructures. Among diverse 2D materials, black phosphorus (BP) is promising candidate for mid-IR applications, because it owns a direct and narrow band gap. In this talk, we will introduce a new type of hybrid photodetector, which is composed of black phosphorus/molybdenum ditelluride van der Waals heterostructures integrated with a silicon-on insulator waveguide. Our mid-infrared optoelectronic characterizations indicate our device could exhibit high responsivity (up to ~0.85 A/W) and ultrafast rise/decay time (~30ns and ~58ns, respectively) at room temperature condition. In addition, we show its noise equivalent power could be comparable to commercially available photodetectors. Such features suggest its usefulness to practical applications. |
Wednesday, March 8, 2023 8:12AM - 8:24AM |
M21.00002: Bulk photovoltaic effect in 2D materials from density functional theory and real-time dynamics Juan José Esteve-Paredes, Mikhail Malakhov, Alejandro Uría, Juan José Palacios, Antonio Picón The bulk photovoltaic effect (BPVE) is a phenomenon that consists in the generation of a DC current in a material under ilumination with strong enough oscillating electric fields. This effect is intrinsic and occurs in non-centrosymmetric materials without the need of heterostructures or interfaces. The second-order current that contributes to the BPVE is known as the shift-current. First-principles Density Functional Theory (DFT) calculations of this quantity have been carried out during the last decade, seeking efficient materials that can be used for solar energy conversion. In this talk, we present two DFT-based methodologies to evaluate the first and second-order (DC) responses based on (i) evaluating the frequency-dependent perturbative expressions and (ii) soving the time-dynamical equations for the density matrix incuding an electric pulse. The use of Gaussian basis sets saves computational effort, where typical expressions containing expensive “sums over bands” become expeditious. More remarkably, our time-dynamics approach allows to include electron-hole effects in the calculation of shift currents, a theoretical challenge with almost no general understanding yet. We apply our methodology to several 2D crystals that elucidate the enormous changes in the shift current, inlcuding both a huge redshift in energy and qualitative changes in its shape, when one goes beyond a single-particle DFT approach. |
Wednesday, March 8, 2023 8:24AM - 8:36AM |
M21.00003: Semimetal-Monolayer Transition Metal Dichalcogenides Photodetectors for Wafer-Scale Ultraviolet Photonics Akm S Newaz, Hon-Loen Sinn, Aravindh Kumar, Eric Pop Atomically thin two-dimensional (2D) transition metal dichalcogenides (TMDs), such as MoS2, are promising candidates for nanoscale photonics because they demonstrate strong-light matter interactions due to the planar exciton effect and because of their stability in air. However, Fermi level pinning due to metal-induced gap (MIGS) states at the metals-monolayer MoS2 interface limits the application of optoelectronic devices based on conventional metals because of the relatively high contact resistance of the Schottky contacts that lead to poor current-delivery capability. On the other hand, a semimetal-TMD-semimetal device can overcome this limitation, where the MIGS are sufficiently suppressed and can result in ohmic contacts. Here we demonstrate the optoelectronic performance of a bismuth-monolayer (1L) MoS2-bismuth device with ohmic electrical contacts and extraordinary optoelectronic properties. To address the wafer-scale production, we grew full coverage 1L MoS2 by using the solid-source chemical vapor deposition method. We measured high photoresponsivity of 300 A/W in the UV regime at 77 K, which translates into an external quantum efficiency (EQE) ~ 1000 or 105%. By measuring time-resolved photocurrent, we have found that the 90% rise time of our devices at 77 K is 0.1 ms, which suggests that the current devices can operate at the speed of ~ 10 kHz. The combination of large-array device fabrication, high sensitivity, and high-speed response offers great potential for applications in photonics that includes integrated optoelectronic circuits, light sensing, and pixel arrays for high-resolution cameras, biomedical imaging, covert communication, and fire monitoring. |
Wednesday, March 8, 2023 8:36AM - 8:48AM |
M21.00004: Dirac plasmon-assisted dynamically tunable LWIR photodetection at room temperature based on nanopatterned monolayer graphene Muhammad Waqas Shabbir, Arindam Dasgupta, Tianyi Guo, Manobina Karmakar, Debashis Chanda The detection of long-wave infrared (LWIR) photons is challenging at room temperature due to the low photon energy. The uncooled microbolometers suffer from low sensitivity, slow response, and tedious multi-step complex lithographic processes. Mercury Cadmium Telluride (MCT) detector needs cryogenic cooling and complex, low-yield ROIC hybridization. The newly emerging colloidal quantum dot (CQD) based detectors suffer from high dark currents, inefficient carrier transport, and poor LWIR performance. We present a spectrally selective ultrafast LWIR detector based on CVD grown large area nanopatterned graphene (NPG). By introducing nanopatterns (circular holes arranged in a hexagonal array), the absorption in the LWIR band for monolayer NPG coupled to the Fabry Perot cavity is enhanced up to 80% because of excitation of cavity –coupled localized surface plasmons (LSPs) around the edges of circular holes. This asymmetric device’s active detector area consists of partially nanopatterned graphene. The LSPs on the nanopatterned side create hot carriers that give rise to the Seebeck effect at room temperature, achieving a large responsivity of R ≈ 104 V/W, a detectivity exceeding D* ≈ 109 Jones, and an ultrafast response time of the order of 100 ns in 8-12 μm band. |
Wednesday, March 8, 2023 8:48AM - 9:00AM |
M21.00005: Tunable excitons in multilayer graphene for on-chip infrared spectroscopy Dasol Kim, Zhengguang Lu, Tonghang Han, Elaine D McVay, Kyung-Han Hong, Tomas Palacios, Long Ju AB-stacked bilayer graphene (BLG) and ABC-stacked trilayer graphene (TLG) host strong exciton resonances in mid-infrared to far-infrared spectral range. These excitons can be tuned by an out-of-plane electric field in a dual-gated field effect transistor device configuration. Firstly, I will show the basic exciton properties by using an FTIR-photocurrent spectroscopy technique, which feature a linewidth down to ~0.4 meV and a peak infrared absorption of more than 40%. Then I will demonstrate the concept of on-chip spectroscopy using these graphene devices as tunable infrared detectors. By electrically scanning the exciton resonance across the infrared spectral range, sharp absorption features corresponding to molecular fingerprints can be readily resolved in both the DC detection mode and AC-modulated detection mode. These on-chip spectrometers avoid conventional grating-based and FTIR spectrometers—opening up new routes for infrared detection and spectroscopy. |
Wednesday, March 8, 2023 9:00AM - 9:12AM |
M21.00006: Optical Response and Hot Carrier Dynamics simulations for High Photoconversion in monolayers of Tellurene Alexandre R Rocha, Cesar P Villegas An appropriate band gap and long relaxation times for photoexcited hot carriers are some of the features required from a good candidate for photovoltaic applications. In this talk, using of ab initio many-body perturbation theory, including the spin–orbit interaction, we investigate the photocarrier generation and dynamics in α-Tellurene [1]. We show that photoexcited electrons are mainly generated in the near-infrared range, forming excitons that are strongly bound, compared to its bulk counterpart. We also explore the role of the electron–phonon and electron-electron interactions in the relaxation of charged carriers. We find that the electronic states in the first conduction band minimum couple weakly with phonons, yielding longer hot electron lifetimes, and mean free paths up to 37 nm. We also show that the extraction of hot holes may result in a challenging task as these carriers possess sub-3 nm mean free paths. We finally estimate that 1-nm-thick α-Te provides a short-circuit current density of 6.7 mA/cm2 and a maximum power conversion efficiency of 4.4%, comparable to other layered materials, which highlights its potential for efficient photovoltaic device development. |
Wednesday, March 8, 2023 9:12AM - 9:24AM |
M21.00007: Simulation on tip-induced nanoscale magneto-photocurrent in 2-dimensional electron systems Wenjun Zheng, Makoto Tsuneto, Zengyi Du, Yinming Shao, Suheng Xu, Ran Jing, Dmitri N Basov, Mengkun Liu Lattice symmetry and electron properties of 2-dimensional (2D) materials can be investigated by measuring photocurrent. In this work, we use the magneto scanning near-field optical microscope (m-SNOM) to map the nanoscale photocurrent of graphene under a magnetic field. Via tip-enhanced optical excitation and tip-induced local thermogradient, the magnetic field yields an anisotropic magnetothermal effect. We will show our simulation of the 2D nanoimaging of tip-initiated photocurrent/voltage with varying temperatures, magnetic field, incident photon energy, and electric properties of 2D electron systems. We found that our toy model matches recent experiments very well. The calculation predicts a quantized and edge photocurrent which would be observed by m-SNOM at low temperatures in future experiments. |
Wednesday, March 8, 2023 9:24AM - 9:36AM |
M21.00008: Visualizing Moiré ferroelectricity by plasmons and nano-photocurrent in twisted WSe2 structures Shuai Zhang, Yang Liu, Zhiyuan Sun, Xinzhong Chen, Baichang Li, Samuel L Moore, Song Liu, Sebastian E Rossi, Jordan M Fonseca, Birui Yang, Matthew Fu, Tsaichun Pan, Dorri Halbertal, Xinyi Xu, James Schuck, Xiaodong Xu, Xiaoyang Zhu, Abhay N Pasupathy, Mengkun Liu, Michael M Fogler, James C Hone, Dmitri N Basov Ferroelectricity, with spontaneous electric polarization, in two dimensional (2D) materials enriches assembled van der Waals heterostructures with intriguing properties. Recently, the already wide spectrum of ferroelectric physics and applications has further broadened following the discovery of moiré ferroelectricity at the interfaces of stacked 2D materials. In these moiré ferroelectric materials, the polarization amplitude and its switching are expected to be governed by the local stacking configurations. In addition, it has been extensively predicated that such ferroelectric domains could influence both optical and optoelectronic responses. However, probing these properties remains challenging because the moiré scale is far below the optical diffraction limit. Here, we employ scattering-type scanning near-field optical microscopy (s-SNOM) and photocurrent nanoscopy to study the ferroelectricity in marginally twisted WSe2 at the nanometer scale. The ferroelectric domains are visualized via the plasmonic excitation. Ferroelectric polarization direction and magnitude can be extracted from the plasmonic excitation spectra. Moreover, the photocurrent nanoscope demonstrates that the optoelectronic properties can be non-volatilely modulated by the ferroelectric domains. These findings offer a new paradigm for studying ferroelectricity and open up new prospects for optoelectronic devices. |
Wednesday, March 8, 2023 9:36AM - 9:48AM |
M21.00009: Efficient brightening of momentum-indirect dark excitons in ML InSe Shao-Yu Chen, Naomi T Paylaga, Chang-Ti Chou, Jiawei Ruan, Chia-Chun Lin, Takashi Taniguchi, Kenji Watanabe, Raman Sankar, Yang-Hao Chan, Wei-Hua Wang Manipulating bright and dark excitons in two-dimensional (2D) materials is a key to understanding many-body correlations of exciton and further developing exciton-mediated applications. On the one hand, bright excitons can directly couple to the light and exhibit great oscillator strengths. On the other hand, dark excitons have a much longer population lifetime and diffusion length, greatly enhancing the exciton-matter interactions. In this work, we investigated the photoluminescence of hexagonal boron nitride-encapsulated monolayer indium selenide (ML InSe). Remarkably, for the first time, we found ML InSe exhibits pronounced luminescence from the momentum-indirect dark excitons, comparable to the few-layer and bulk counterparts. The brightening of dark exciton in ML InSe is attributed to the efficient acoustic phonon-assisted recombination facilitated by strong exciton-phonon coupling and the extended wavefunction in momentum space. Moreover, the asymmetric line shape in PL spectra for atomically thin InSe can be well accounted for by a carrier localization model, reflecting the unique properties of long lifetime and diffusion length of dark excitons. These unique excitonic properties of atomically thin InSe provide potential avenues for manipulating the tightly-bound dark excitons of 2D material-based photovoltaic and photocatalytic applications. |
Wednesday, March 8, 2023 9:48AM - 10:00AM |
M21.00010: Bulk photovoltaic effect in 2D materials with electron-phonon interactions from first-principles Manuel Antonio A García Blázquez, Juan José Palacios, Juan José Esteve-Paredes The generation of a direct current in a solid under a uniform oscillating light field is a non-linear optical phenomenon known as bulk photovoltaic effect (BPVE). In non-magnetic materials under a linearly polarized field, the BPVE has two frequency-dependent contributions: the shift current, an intrinsic quantity derived from electrons in the perfect lattice; and the ballistic current, which arises from scattering processes (in particular the electron-phonon interaction). The possibility of realizing this inherently quantum effect in homogeneous, non-centrosymmetric materials has made BPVE an increasingly important topic in photovoltaics, but realistic numerical calculations have not been possible until recent years. Here we present a symmetry analysis of the atomistic expressions for the shift current and the phonon-assisted ballistic current, which allows to obtain convenient local selection rules in the Brillouin zone (BZ) as well as efficient implementations in the irreducible part of the BZ. These general results are then applied to the calculation of these two quantities in two-dimensional materials, such as an insulating single layer of GaSe, from first-principles electron and phonon calculations with the software Crystal. This is, to our knowledge, one of the first instances in which the phonon-assisted ballistic current has been computed in 2D materials. The impact of in- and out-of-plane strain on the shift current is also demonstrated, in regards to both numerical magnitudes and local selection rules. |
Wednesday, March 8, 2023 10:00AM - 10:12AM |
M21.00011: Active THz Optoelectronics Using Multilayer Graphene: tunable filters, phase modulators, and resonators. Sachin Sharma, Zhi Cai, Haley A Weinstein, Indu Amma, Stephen B Cronin, Ioannis Chatzakis We present the active manipulation of THz waves by means of optoelectronic devices based on multilayer graphene (MLG) structures (~100 layers thick). The devices are based on the reversible intercalation of ions, which changes the carrier density of the MLG by as much as 2 orders of magnitude, thus, tuning the complex dielectric function ε(ω) in a controllable and reversible way. We tested our devices using terahertz time domain spectroscopy (THz TDS), and we quantified our ability to modulate terahertz radiation/light. Furthermore, finite difference time domain (FDTD) calculations were carried out to model and interpret the voltage-induced changes in ε(ω), extract phase information, and predict the behavior of more complex structures and devices. We observed under various applied voltages a clear shift in the reflected peak position to earlier times (for positive applied voltages) and later times (for negative applied voltages). The apparent peak delay and peak advance can be understood on the basis of phase shifts obtained by a modulation in the complex dielectric function (i.e., ε1 and ε2). Assuming a frequency of 1 THz, this modulation here corresponds to phase shifts of Δφ = ±1200. These results stand in contrast to those reported previously in which negligible phase shifts are observed. |
Wednesday, March 8, 2023 10:12AM - 10:24AM |
M21.00012: Far-Infrared Optical Spectroscopy of Quantum Matter at Millikelvin Temperatures Michael Onyszczak, Ayelet J Uzan, Yue Tang, Pengjie Wang, Yanyu Jia, Guo Yu, Tiancheng Song, Sanfeng Wu Many interesting quantum phenomena are associated with strongly correlated gaps at the energy scale in the far-infrared regime, and their observations are often optimized at ultra-low temperatures. They include integer and fractional quantum Hall effects, superconductivity in 2D materials and correlated states in moiré systems. Optical spectroscopy is a useful probe in determining the nature of these low energy states and excitations especially because light-matter interactions can couple to neutral excitations that are normally invisible to electronic probes. In this talk, we describe our efforts in developing a novel instrumental platform for implementing far-infrared optical spectroscopy on high quality 2D samples at milli-Kelvin temperatures. |
Wednesday, March 8, 2023 10:24AM - 10:36AM |
M21.00013: Far infrared Optical Studies of Monolayer WTe2 at Ultralow Temperatures Ayelet J Uzan, Michael Onyszczak, Yue Tang, Pengjie Wang, Yanyu Jia, Guo Yu, Tiancheng Song, Sanfeng Wu Monolayer tungsten ditelluride (WTe2) has been established as a highly intriguing 2D material, which exhibits various topological and correlated quantum phases, such as the quantum spin Hall insulator, excitonic insulator, and gate-induced superconductivity. Yet theoretical understanding of this unique 2D crystal remains poorly developed, including even its basic band structure and the effects of electron correlations on it. In this talk we describe our efforts in probing its electronic phases using our newly developed instrument that integrates far-infrared optical spectroscopy with a dilution refrigerator. With optics, we hope to reveal new information about monolayer WTe2 that is hidden from electronic transport |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700