Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session F42: Non-Chalcogenide 2D Materials and Quantum DotsLive
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Sponsoring Units: DCMP Chair: Tiancong Zhu, UC Berkeley |
Tuesday, March 16, 2021 11:30AM - 11:42AM Live |
F42.00001: Widely Tunable Mid-Infrared Light Emission in Thin-Film Black Phosphorus Chen Chen, Xiaobo Lu, Bingchen Deng, Xiaolong Chen, Qiushi Guo, Cheng Li, Chao Ma, Shaofan Yuan, Kenji Watanabe, Takashi Taniguchi, Li Yang, Fengnian Xia We report the widely tunable mid-infrared light emission from dual-gate hexagonal boron nitride (hBN)/Black Phosphorus (BP)/hBN heterostructure devices. The photoluminescence (PL) from an intrinsic ~20-layer BP flake can be continuously tuned from 3.7 to 7.7 μm with a moderate displacement field of up to 0.48 V/nm, spanning 4 μm in mid-infrared. The PL emission remains linearly polarized under the external bias due to the preservation of the optical transition rule. The gate dependence of the band structure and optical conductivity in BP have been further investigated by first-principle calculations. Moreover, the radiative decay probably dominates over other nonradiative decay channels in the PL experiments. Our results reveal the great potential of thin-film BP in tunable mid-infrared light emitting and lasing applications. |
Tuesday, March 16, 2021 11:42AM - 11:54AM Live |
F42.00002: Prediction of novel 2D auxetic semiconductors with high carrier mobilities and unusually low lattice thermal conductivities Xin Chen, duo wang, Xiaobiao Liu, Linyang Li, Biplab Sanyal A perpetual search for new two-dimensional (2D) materials with novel properties has led to many important discoveries in recent times. Using evolutionary structure search methods combined with ab initio theory, we have found two low energy structural types of 2D A2B (A=Cu, Ag, Au, and B = S, Se) auxetic semiconductors having direct bandgaps in the range 1.09−2.60 eV and high electron mobilities. Cu2B and Ag2B have the possibility of achieving highly anisotropic hole transport with the application of a uniaxial strain. Due to the ionic bonding nature, s-A2B structures have unusually low lattice thermal conductivities down to 1.5 W m−1 K−1 at 300 K, showing great promise for new generation thermoelectric devices. Moreover, they are found to have ultralow Young’s moduli (down to 20 N/m), which are lower than most previously reported 2D materials. Finally, some of these structures are found to have in-plane negative Poisson’s ratios under the application of strain along the diagonal direction. |
Tuesday, March 16, 2021 11:54AM - 12:06PM Live |
F42.00003: Spinoidal Doping Structures in Sulfurized Molybdenum Carbide Anna Binion, Lavish Pabbi, Riju Banerjee, Fu Zhang, Mauricio Terrones, Eric Hudson Nanometer scale control of doping variations is a key part of the development of nanoscale electronics. In this talk, we report results of STM and AFM investigations of spatial doping variations in sulfurized MoC. We find that highly doped regions appear in a spinodal pattern, and that although the surface of the material remains atomically flat, these large doping variations lead to apparent height changes of up to one nanometer in STM topographs, with sharp transitions between doped and undoped regions, giving the appearance of pits. We will discuss the impact of these doping variations on local density of states measurements, their interplay with Moire patterns, and their evolution with further sulferization. |
Tuesday, March 16, 2021 12:06PM - 12:18PM Live |
F42.00004: Extraordinary Phase Coherence Length in Epitaxial Halide Perovskites Liangji Zhang, Isaac King, Kostyantyn Nasyedkin, Pei Chen, Lili Wang, Richard Staples, Richard R Lunt, Johannes Pollanen Inorganic halide perovskites have emerged as a promising platform for a wide range of applications from solar energy harvesting to computing. With the recent advent of epitaxial thin film growth of halide perovskites it is now possible, for the first time, to investigate low-dimensional quantum electronic devices based on these materials. We leverage advances in vapor-phase epitaxy of halide perovskites to perform low-temperature quantum electrical and magnetotransport measurements on single-domain cesium tin iodide (CsSnI3) epitaxial thin film devices. The low field magnetoresistance carries signatures of coherent quantum interference effects and spin-orbit coupling. We find that the low-temperature phase coherence length for charge carriers in this material exceeds that reported in two-dimensional electron systems in silicon, gallium arsenide, and graphene. These results open the door to epitaxial halide perovskite heterostructures for investigating and exploiting coherent quantum electronic effects for applications in spintronics and spin-orbitronics. |
Tuesday, March 16, 2021 12:18PM - 12:30PM Live |
F42.00005: Highly coherent single photon emission from charge tunable GaAs quantum dots Giang Nguyen, Liang Zhai, Matthias Löbl, Clemens Spinnler, Alisa Javadi, Julian Ritzmann, Andreas D. Wieck, Arne Ludwig, Richard J. Warburton Efficient generation and detection of coherent single photons are key to advances in photonic quantum technologies. Among many quantum emitters, GaAs quantum dots are promising as they emit close to the red part of the spectrum. This wavelength range is important as it contains the peak sensitivity of silicon detectors and operating wavelengths of a rubidium memory. However, GaAs QDs usually suffer from random telegraph noise (blinking) due to an unstable charge environment. This charge noise also leads to broadened optical linewidths and photon-bunching (J.-P. Jahn, et al., Phys. Rev. B 92, 245439 (2015)). |
Tuesday, March 16, 2021 12:30PM - 12:42PM Live |
F42.00006: EDSR spectroscopy of a single hole confined in a gated GaAs double quantum dot Olivia Ellis, Marek Korkusinski, Sergei Studenikin, Aviv Padawer-Blatt, Jordan Ducatel, Alex Bogan, Louis Gaudreau, David Guy Austing, Andrew Stanislaw Sachrajda, Lisa A Tracy, Terry Hargett, John L. Reno This research presents theoretical and experimental studies of a single hole confined in a gated GaAs double quantum dot (DQD) [1,2], using microwave excitation to achieve Electric Dipole Spin Resonance (EDSR). Weak hyperfine hole-nuclear interactions and strong spin-orbit interactions (SOI) make the hole spin a promising candidate for a qubit. Electrical excitation via EDSR, apart from performing spin qubit rotations, is a powerful spectroscopic tool in determining the energy spectra of the confined hole. When plotted as a function of interdot detuning, B-field, and interdot tunneling, the spectra reveal tunability of the hole effective g-factor using electrical means. EDSR also reveals hybridization of hole orbitals and lead states, giving another mechanism of the g-factor tuning. The calculated spectra are compared to the experimental results of EDSR spectroscopy detected in transport in the high source-drain voltage regime. Given the accurate fits to the experimental data, the model can be used as a predictive tool in design of coherent control of the hole spin qubit. |
Tuesday, March 16, 2021 12:42PM - 12:54PM Live |
F42.00007: k.p theory of quantum dots with smooth alloy profiles Luc Robichaud, Jacob J Krich Due to their tunable electronic and optical properties, epitaxial quantum dots have many applications including lasers, solar cells and water splitting. Since most applications require that these electronic and optical properties be carefully tuned, models must capture all essential physics to enable accurate prediction of device functionality. Most quantum dot electronic structure models assume sharp material interfaces, even though epitaxial quantum dots frequently have alloy diffusion, creating diffuse interfaces. We present a Fourier-space k.p method for modelling the electronic structure of wurtzite quantum dots with continuous alloy profiles. We calculate strain and piezoelectric potentials with elastic and dielectric constants that vary smoothly with the alloy profile. Our method calculates single-particle electronic states of either isolated quantum dots or arrays of dots. We demonstrate our methodology on 1D GaN/InGaN quantum dot arrays, representing quantum dots grown in wires. In all cases, the effects of indium diffusion as occurs in molecular beam epitaxy are found to significantly modify the electronic structure of the dots. |
Tuesday, March 16, 2021 12:54PM - 1:06PM Live |
F42.00008: Ultra-long-working-distance Spectroscopy of Single Nanostructures with Aspherical Solid Immersion Microlenses Aleksander Bogucki, Lukasz Zinkiewicz, Magdalena Grzeszczyk, Wojciech Pacuski, Karol Nogajewski, Tomasz Kazimierczuk, Aleksander Rodek, Jan Suffczynski, Kenji Watanabe, Takashi Taniguchi, Piotr Wasylczyk, Marek Potemski, Piotr Kossacki In this work, we present aspherical micro-lenses which redirect emitted photons from semiconductor nanostructure into an ultra-narrow light cone of NA=0.016 - the outcoming light can be collected by a 1 inch-diameter lens at the distance of 590 mm from the sample [1]. The resulting working distance is more than 70 times longer than the one offered by conventional microscope objectives. Micro-lenses were fabricated by Two-Photon Polymerisation Direct Laser Writing (TPP-DLW), the technique which allows for three-dimensional printing of micro-objects made of transparent non-conductive resin that withstands cryogenic temperatures [2]. |
Tuesday, March 16, 2021 1:06PM - 1:18PM Live |
F42.00009: First principles study of the structural and electronic properties of the in-plane SiC/GeC heterostructures Safia Alharbi, Kazi Jannatul Tasnim, Ming Yu The atomic structures and electronic properties of the in-plane heterostructures composed of the polar SiC and GeC sheets (SiC/GeC) have been systematically studied within the framework of density functional theory. The mismatch of 5.4% between SiC and GeC sheet induces a strain in the combined heterostructures leading to a compression in the GeC domain and an expansion in the SiC domain, respectively. It was found that such strain strongly influences the electronic properties on the densities of states, the band gap, and the transition from in-direct to direct band gap. The partial charge distribution density, charge transfer, and the charge density difference analyses also revealed the effect of interface depending on either the armchair or the zigzag heterostructures. These results provide significant information to clarify the correlation between atomic structures and electronic properties of the in-plane SiC/GeC heterostructures and a fundamental picture for further theoretical studies and device design based on such ionic-like heterostructures. |
Tuesday, March 16, 2021 1:18PM - 1:30PM Live |
F42.00010: Exciton Fine Structure in Lead Chalcogenide Quantum Dots: Valley Mixing and Crucial Role of Intervalley Electron−Hole Exchange Serguei Goupalov, Ivan D. Avdeev, Mikhail O. Nestoklon We study the exciton fine structure in quantum dots of multi-valley lead chalcogenides [1]. We demonstrate that inter-valley electron-hole exchange interaction, ignored in previous studies, dramatically modifies the exciton fine structure and leads to appearance of the ultra-bright valley-symmetric spin-triplet exciton state dominating inter-band optical absorption. Valley mixing leads to brightening of other symmetry-allowed spin-triplet states which dominate low-temperature photoluminescence. Our results are in agreement with recent experiments on optical spectroscopy of individual PbS/CdS core/shell quantum dots yielding temperature dependences of photoluminescence line-shapes [2]. |
Tuesday, March 16, 2021 1:30PM - 1:42PM Not Participating |
F42.00011: Three terminal vibron coupled hybrid quantum dot thermoelectric
refrigeration. Swarnadip Mukherjee, Bitan De, Bhaskaran Muralidharan A three terminal nanoscale refrigeration concept [1] based on a |
Tuesday, March 16, 2021 1:42PM - 1:54PM On Demand |
F42.00012: Engineering 2D monolayer structures in II-V binary Zintl-phase compounds ZnX (X = As, Sb, Bi) Dinesh Thapa, Bipin Lamichhane, Chandani Nilanthika Nandadasa, Junseong Song, Sung Wng Kim, Kimoon Lee, Seong-Gon Kim Recently, two-dimensional (2D) materials have become an intriguing material because of its numerous applications in spintronics, optoelectronics, and sensing. We present the engineering of 2D monolayer structures in the orthorhombic compounds ZnX (X = As, Sb, Bi) that belong to the space group pbca using density functional theory (DFT). We showed the stability of the 2D monolayer (ML) structures on such materials based on i) the exfoliation energy criterion and ii) the phonon dispersion curve with the absence of imaginary modes. Our calculations on electronic band structures indicate the semiconducting nature of all the ML structures with a sizable bandgap of 1.52 eV (indirect), 0.94 eV (direct), and 0.63 eV (direct) in ZnX with X = As, Sb, and Bi respectively with decreasing trend of the forbidden gap with increasing size of electronegative X-atom. Surprisingly, the electronic properties of ZnBi change while going from metallic bulk to semiconducting monolayer. Our theoretical results on the monolayers of ZnX will pave the way for other theoretical and experimental researchers for further investigations. |
Tuesday, March 16, 2021 1:54PM - 2:06PM On Demand |
F42.00013: Integer and multiple fractional values of RH in gateless, millimeter-scale, monolayer epitaxial graphene p-n junctions Dinesh Patel, Albert F Rigosi, Martina Marzano, Mattias Kruskopf, Chieh-I Liu, Hanbyul Jin, David B Newell, Randolph E. Elmquist, Chi-Te Liang We grew nearly defect-free and monolayer epitaxial graphene (EG) on a hexagonal SiC substrate of centimeter-scale at 18500 C and developed a new technique to fabricate electrostatic-gate-free, monolayer EG devices. These devices were gated by static chemical doping, with designs including p-type and n-type regions in series and in 2x2 checkerboard patterns, using simple ultraviolet photolithography. This technique significantly reduces the device processing time compared to electron beam lithography and resulted in approximately 200 nm wide dissipation-free junctions. We performed the electromagnetic measurements of integer (1, 2, 3, 4, 5, 6, 7, and 8) and fractional (2/3, 8/7, 6/17, 12/13, 24/29, 32/57, and many more) multiples of the quantized Hall resistance in the ν=2 plateau (RH ≈12906 Ω) by applying single and multiple current injection points, respectively. Finally, we modeled all measured experimental data using an LTspice circuit simulator and predicted more complex embodiments of the quantum Hall resistance checkerboard. These simulations highlight the parameter space within which these devices could operate. |
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