Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session G67: Wide Band Gap, Diamond, and NV CentersFocus Recordings Available
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Sponsoring Units: DMP Chair: Vigneshwaran Chandrasekaran, Los Alamos National Lab; Matthew McCluskey, Washington State University Room: Hyatt Regency Hotel -Hyde Park |
Tuesday, March 15, 2022 11:30AM - 12:06PM |
G67.00001: Impurity-related Charge-state Transition Levels in β-Ga2O3 Invited Speaker: Lasse Vines Gallium sesquioxide (β-Ga2O3) is an ultra-wide band gap semiconductor (Eg ≈ 4.8 eV) which has attracted considerable attention in recent years for its potential use in power electronics and UV photo-detectors. For β-Ga2O3 to live up to its potential, the influence of impurity related defects on its electrical and optical properties needs to be better understood. Indeed, deep level transient spectroscopy (DLTS) and steady state photocapacitance spectroscopy (SSPC) show that several electrically active defect levels are present in as grown material, or may arise after irradiation or thermal treatments. For example, iron and titanium are typical impurities in bulk β-Ga2O3, and we have shown that these impurities exhibit defect levels in the upper part of the band gap, as observed by DLTS and SSPC, and also confirmed by density functional calculations. Using SSPC, it has also been possible to identify the optical signatures related to Fe and Ti. Here, we will present the status of understanding electrically active defects related to impurities in β-Ga2O3, and discuss recent results on defect levels arising after hydrogenation. |
Tuesday, March 15, 2022 12:06PM - 12:18PM |
G67.00002: Single photon emission from donor bound excitons in ZnSe quantum wells Aziz Karasahin, Robert M Pettit, Nils von den Driesch, Marvin M Jansen, Alexander Pawlis, Edo Waks Donor impurities in ZnSe have been shown to create shallow bound excitons. The radiative recombination of such bound excitons can be employed for single-photon generation. In this study, we investigate Cl doped ZnSe quantum wells for their radiative properties. We demonstrate single-photon generation from Cl-bound excitons. We support our findings with photoluminescence excitation (PLE) and resonant photoluminescence measurements. In addition, we characterize the temperature-dependent lifetime of the emission and discuss the possible decay mechanisms. Lastly, we investigate the Zeeman levels of the ground state electron by performing magneto-spectroscopy. |
Tuesday, March 15, 2022 12:18PM - 12:30PM |
G67.00003: Cascaded emission from localized biexcitons in ZnSe Robert M Pettit, Aziz Karasahin, Nils von den Driesch, Marvin M Jansen, Alexander Pawlis, Edo Waks We report on the observation of cascaded single photon emission from localized biexcitons in a ZnSe quantum well delta doped with chlorine donor atoms. The formation of localized biexciton states was verified through excitation power density and polarization resolved micro-photoluminescence spectroscopy. The emission cascade was observed via time-resolved lifetime decay and single photon correlation measurements. |
Tuesday, March 15, 2022 12:30PM - 12:42PM |
G67.00004: Rare-earth defects in wide band-gap semiconductors Khang Hoang Rare-earth (RE) defects are of great interest for luminescence and quantum information science. Yet defect physics of RE-doped wide band-gap semiconductors is currently not well understood. First-principles defect calculations based on a hybrid DFT/Hartree-Fock approach can provide a detailed understanding of the atomic and electronic structure, energetics, and optical properties of RE dopants in solid compounds [1]. In this talk, we discuss (i) the interaction between the RE dopants in the lanthanide series and the GaN host and its implications on intra-f and band-to-defect luminescence, and (ii) RE-related defects in CaS and SrAl2O4 and their role in persistent luminescence mechanisms. [1] K. Hoang, Phys. Rev. Mater. 5, 034601 (2021). |
Tuesday, March 15, 2022 12:42PM - 12:54PM |
G67.00005: Multiconfigurational study of negatively charged silicon vacancy in 4H-SiC Kamal Wagle, Aleksander L Wysocki, Sophia E Economou, Pratibha Dev, Kyungwha Park Deep point defects in wide-gap semiconductors have emerged as promising systems for quantum information science applications. The prototype of such deep defects is the negatively charged nitrogen-vacancy defect in diamond. Recently, silicon carbide (SiC) has drawn attention as an alternative host for point defects due to its low price, mature fabrication technology, and telecom-range emission frequencies. A negatively charged silicon vacancy defect in 4H-SiC has a unique ground-state spin quartet and first-excited spin doublet with optical spin control and long spin coherence time. Although defect states inherently have many-electron characteristics, theoretical studies of defects are, so far, predominantly based on density-functional theory. We investigate the electronic structure of the Si vacancy defect by employing multiconfigurational quantum chemistry methods, including spin-orbit coupling. We recently demonstrated the predictive power of these methods by employing them to nitrogen vacancy center in diamond (Bhandari et al., Physical Review B 103, 014115 (2021)). For each defect, we determine the excitation energies between quartets and doublets, or within quartets or doublets, as well as the corresponding wave functions. Our results are compared to experimental data. |
Tuesday, March 15, 2022 12:54PM - 1:06PM |
G67.00006: Giant carrier capture cross section by an individual nitrogen vacancy center in diamond: Applications and theory Artur Lozovoi, Gyorgy Vizkelethy, Edward Bielejec, Yunheng Chen, Marcus Doherty, Johannes Flick, Carlos A Meriles The recent demonstration of charge transport between individual nitrogen vacancy centers in diamond1 opens up new opportunities for applications in quantum sensing and quantum information science, as well as for exploring fundamental physics of carrier transport and capture in semiconductors. In this talk, we discuss experimental results demonstrating “giant” hole capture cross section by a single negatively charged nitrogen vacancy center – 3*10-3 μm2. To explain this observation, we propose a theoretical framework that relies on unscreened, long-range Coulomb attraction between the trap and the carrier, which allows the hole to enter bound orbitals thereby forming bound exciton states. Carrier capture based on this process requires ultralow defect concentrations and is efficient at room temperatures. The proposed framework is supported by DFT and Monte Carlo calculations. Building on this, we explore the behavior of capture cross section as a function of temperature and applied electric field. As an immediate practical application, we demonstrate that the giant NV- capture cross section can be utilized for detection of dark charge emitters in diamond that otherwise remain optically undetectable2. |
Tuesday, March 15, 2022 1:06PM - 1:18PM |
G67.00007: Calculating the Adiabatic Charge Transition Level for the NV- to NV0 Transition in the Presence of Substitutional N or P in Diamond Rodrick Kuate Defo, Xingyu Zhang, Steven L Richardson, Efthimios Kaxiras Electroluminescence from color centers such as the nitrogen vacancy in diamond (NV-) is desirable as it would allow for nanometer scale spin qubit control. However, even when a point defect shows the signature of NV- in photoluminescence only the NV0 signature is observed in electroluminescence. Such an observation suggests ionization of the NV- before it achieves fluorescence. We have developed a formalism for calculating the adiabatic charge transition level for the NV- to NV0 transition in the presence of a substitutional N or P donor. When the NV- is in the presence of a substitutional P donor or a high concentration of substitutional N donors we indeed find that the calculated adiabatic charge transition levels correspond to ionization energies for the NV- that are smaller than the energy of its zero-phonon line.1 |
Tuesday, March 15, 2022 1:18PM - 1:30PM |
G67.00008: Demonstration of NV-detected NMR spectroscopy at 8.3 Tesla Benjamin M Fortman, Laura Mugica-Sanchez, Noah Tischler, Cooper M Selco, Yuxiao Hang, Karoly Holczer, Susumu Takahashi High field nuclear magnetic resonance (NMR) spectroscopy offers high spectral resolution and new insights into the study of complex biomolecules. The nitrogen-vacancy (NV) center, due to its unique properties, has enabled widespread study of nanoscale NMR at low magnetic fields [1]. However, conventional NV-detected NMR based on AC magnetic field sensing is not applicable at high magnetic fields, requiring the development of alternate techniques. Furthermore, there have been few studies of NV-detected NMR at high fields due to the technical challenges involved [2]. Within this work, we explore an NV-detected NMR technique suitable for applications of high field NMR [3]. We demonstrate optically detected magnetic resonance (ODMR) with the NV Larmor frequency of 230 GHz at 8.3 Tesla, corresponding to a proton NMR frequency of 350 MHz. We demonstrate the first measurement of electron-electron double resonance detected NMR (EDNMR) using the NV center and successfully detect 13C nuclear bath spins. The described technique is limited by the longitudinal relaxation time (T1), not the transverse relaxation time (T2). This work demonstrates a clear path to NV-detected NMR at even higher magnetic fields. |
Tuesday, March 15, 2022 1:30PM - 1:42PM |
G67.00009: Near-surface NV centers in diamond with reduced decoherence Anton Pershin, Viktor Ivady, Adam Gali The quantum sensors, based on the NV- centers in diamond, are potential game changers for nuclear magnetic resonance (NMR) spectroscopy. In particular, they are able to supply a structural information on the surrounding spins from micron-scale sample volumes and at millimolar concentrations. In the NMR experiment, the signal-to-noise ratio drastically improves by positioning the target close to the NV- center. However, the near-surface NV- centers usually show poor spin-coherence time which precludes high spectral resolution. Here, we show that for the shallowest NV- centers, surface interferes with the alignment of the triplet sublevels and gives rise to a gradual increase of a rhombic zero-field splitting term. By performing the spin-dynamics simulations, we demonstrate that the newly-developed level anti-crossing enables to maintain the coherence time at close to the bulk values, yet providing a substantial improvement in the STN ratio. By calculating the coherence time in distorted NV- centers with the gCCE method, we evaluate the impact of the electron- and nuclear-spins on the property. We also discuss different types of surface termination and identify most suitable surfaces for quantum sensing. |
Tuesday, March 15, 2022 1:42PM - 1:54PM |
G67.00010: The Study of Electronic Properties of Nitrogen-vacancy Center in Diamond Using Band-unfolding Method Hana P Kadarisman, Naoya Yamaguchi, Fumiyuki Ishii The nitrogen-vacancy center in diamond in a negative charge state is a promising candidate for many applications, such as high-resolution sensors of electric fields [1] and qubits in quantum computers [2]. DFT calculations are often performed in a supercell system. However, as the supercell increases, the first Brillouin zone (FBZ) shrinks, and the bands get complicated. We have performed the unfolding-band method calculation to study the electronic properties of nitrogen-vacancy center diamond using the OpenMX code [4]. Our results show that the unfolded band of bulk diamond supercell and nitrogen-vacancy center in diamond have fewer lines than the conventional folded band one. The shapes of the unfolded energy bands agree with the primitive cell band. |
Tuesday, March 15, 2022 1:54PM - 2:06PM |
G67.00011: Optical responses of boron-vacancy defects in strained hexagonal boron nitride Du Li, Li Yang The recently discovered negatively charged boron vacancy defects in hexagonal boron nitride (h-BN), a layered van der Waals material, have great potential for applications of quantum qubit and sensing. However, neutral boron vacancy (VB) and negatively charged boron vacancy (VB-) have similar photoluminescence spectrum, which makes it hard to distinguish VB and VB- by usual optical characteristic tools. In this work, we report first-principles calculation of electronic band structures and optical absorption spectrum of VB and VB- single point defects in monolayer h-BN under external strain. We find that VB and VB- defects exhibit different optical responses to external strain, which may assist to probe the defect types. Meanwhile, the enhanced change of optical spectra of defects in strained h-BN may work for the application of strain sensors. |
Tuesday, March 15, 2022 2:06PM - 2:18PM |
G67.00012: High-throughput identification of point defects in SiC Joel Davidsson, Viktor Ivady, Rickard Armiento, Igor A Abrikosov There is a vast number of possible point defects that can exist in one material. Identifying which defect that best explains experimental observations is challenging and requires a lot of theoretical data. To produce this data, we performed high-throughput ab-initio calculations with ADAQ—a collection of automatic workflows that generates defects, screens for relevant properties such as formation energy and zero-phonon lines, fully calculates additional properties such as zero-field splitting and hyperfine coupling parameters for many different charge and spin states. We have created and screened 8355 single and double intrinsic defects in 4H-SiC. The results for these point defects show which defect type and configurations are the most stable, i.e., on the defect hull. In this presentation, we explore this database to highlight some interesting systems and explain experimental observations. |
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