A5009182091- Semiconductor materials and devices
- Graphene research and applications
- Advanced Chemical Physics Studies
- High-pressure geophysics and materials
- Electronic and Structural Properties of Oxides
- 2D Materials and Applications
- Boron and Carbon Nanomaterials Research
- Semiconductor materials and interfaces
- Ferroelectric and Negative Capacitance Devices
- Quantum and electron transport phenomena
- Ferroelectric and Piezoelectric Materials
- Advancements in Semiconductor Devices and Circuit Design
- Inorganic Fluorides and Related Compounds
- Superconductivity in MgB2 and Alloys
- Surface and Thin Film Phenomena
- MXene and MAX Phase Materials
- Quantum, superfluid, helium dynamics
- Topological Materials and Phenomena
- Transition Metal Oxide Nanomaterials
- Crystallography and molecular interactions
- Diamond and Carbon-based Materials Research
- Advanced NMR Techniques and Applications
- Collagen: Extraction and Characterization
- Quantum many-body systems
- Advanced Thermodynamics and Statistical Mechanics
University of California, Berkeley
2018-2024
The University of Texas at Austin
2023
Lawrence Berkeley National Laboratory
2018-2023
Yale University
2012-2019
Interface (United States)
2016-2019
University of New Haven
2019
Bilkent University
2009
Electronic structure calculations have been instrumental in providing many important insights into a range of physical and chemical properties various molecular solid-state systems. Their importance to fields, including materials science, sciences, computational chemistry device physics, is underscored by the large fraction available public supercomputing resources devoted these calculations. As we enter exascale era, exciting new opportunities increase simulation numbers, sizes, accuracies...
The relative orientation of successive sheets, i.e. the stacking sequence, in layered 2D materials is central to electronic, thermal, and mechanical properties material. Often different sequences have comparable cohesive energy, leading alternative stable crystal structures. Here we theoretically experimentally explore van der Waals bonded material hexagonal boron nitride (h-BN). We examine total electronic bandgap, dielectric response tensor for five distinct high symmetry both bulk bilayer...
The combined effects of doping and biaxial strain explain the transformation HfO<sub>2</sub> grains into ferroelectric phase observed during thermal annealing.
J. Glazer and M. Z. Dogan, Trans. Faraday Soc., 1953, 49, 448 DOI: 10.1039/TF9534900448
The development of room-temperature sensing devices for detecting small concentrations molecular species is imperative a wide range low-power sensor applications. We demonstrate room-temperature, highly sensitive, selective, and reversible chemical based on monolayer the transition metal dichalcogenide Re0.5Nb0.5S2. device exhibits thickness dependent carrier type, upon exposure to NO2 molecules, its electrical resistance considerably increases or decreases depending layer number. selective...
Fine control over material synthesis on the nanoscale can facilitate stabilization of competing crystalline structures. Here, we demonstrate how carbon nanotube reaction vessels be used to selectively create one-dimensional TaTe3 chains or two-dimensional TaTe2 nanoribbons with exquisite chain number nanoribbon thickness and width. Transmission electron microscopy scanning transmission reveal detailed atomic structure encapsulated materials. Complex superstructures such as multichain...
Imposing additional confinement in two-dimensional (2D) materials can yield further control over the associated electronic, optical, and topological properties. However, synthesis of ultra-narrow nanoribbons (NRs) remains a challenge, particularly for transition metal dichalcogenides (TMDs), synthesizing TMD NRs narrower than 50 nm has remained elusive. Here, we report vapor-phase TaS2 NRs. The are grown within hollow cavity carbon nanotubes, thereby limiting their lateral dimensions layer...
Using a real-space high-order finite-difference approach, we investigate the electronic structure of large spherical silicon nanoclusters. Within Kohn-Sham density functional theory and using pseudopotentials, report self-consistent field convergence system with over 100 000 atoms: ${\mathrm{Si}}_{107,641}{\mathrm{H}}_{9,084}$ nanocluster diameter 16 nm. Our approach uses Chebyshev-filtered subspace iteration to speed up eigenspace, blockwise Hilbert space-filling curves sparse matrix-vector...
A single atomic layer of ZrO2 exhibits ferroelectric switching behavior when grown with an atomically abrupt interface on silicon. Hysteresis in capacitance-voltage measurements a gate stack demonstrate that reversible polarization the structure couples to carriers First-principles computations confirm existence multiple stable states and energy shift semiconductor electron result from between these states. This monolayer represents new class materials for achieving devices transcend...
J. H. Schulman and M. Z. Dogan, Discuss. Faraday Soc., 1954, 16, 158 DOI: 10.1039/DF9541600158
The strong interaction at an interface between a substrate and thin film leads to epitaxy provides means of inducing structural changes in the epitaxial film. These induced material phases often exhibit technologically relevant electronic, magnetic, functional properties. 2×1 surface Ge(001) applies unique type constraint on films perovskite oxide BaTiO_{3} where change bonding symmetry non-bulk-like crystal structure BaTiO_{3}. While complex is predicted using first-principles theory, it...
Frustrated interactions can lead to short-range ordering arising from incompatible of fundamental physical quantities with the underlying lattice. The simplest example is triangular lattice spins antiferromagnetic interactions, where nearest-neighbor spin-spin cannot simultaneously be energy minimized. Here we show that engineering frustrated a possible route for controlling structural and electronic phenomena in semiconductor alloys. Using aberration-corrected scanning transmission electron...
We report a Kohn-Sham density functional theory calculation of system with more than 200 000 atoms and 800 electrons using real-space high-order finite-difference method to investigate the electronic structure large spherical silicon nanoclusters. Our choice was 20 nm nanocluster 202 617 13 836 hydrogen used passivate dangling surface bonds. To speed up convergence eigenspace, we utilized Chebyshev-filtered subspace iteration, for sparse matrix-vector multiplications, blockwise Hilbert...
Quantum phase transitions are often embodied by the critical behavior of purely quantum quantities such as entanglement or fluctuations. In regions, we underline a general scaling relation between entropy and one most fundamental simplest measure fluctuations, Heisenberg uncertainty principle. Then, show that latter represents sensitive probe superradiant in standard models photons Dicke Hamiltonian, which embodies an ensemble two-level systems interacting with quadrature single uniform...
We use density functional theory and Monte Carlo lattice simulations to investigate the structure of ZrO$_{2}$ monolayers on Si(001). Recently, we have reported experimental growth amorphous silicon their ferroelectric properties, marking achievement thinnest possible oxide [M. Dogan et al. Nano Lett., 18 (1) (2018)]. Here, first describe rich landscape atomic configurations monocrystalline Si determine local energy minima. Because multitude low-energy find, consider coexistence finite-sized...
Reversibly altering the physical structure of a material on-demand can lead to direct manipulation its electronic properties. In this work localized electron beam is used switch regions nanotube-encapsulated HfTe${}_{2}$ nanoribbons between metallic 1T phase and previously experimentally inaccessible semiconducting 1H phase. The change observed in-situ in high-resolution transmission microscope. Complementary theoretical studies provide details each energetics.
Growing thin films of ferroelectric oxides in direct contact with semiconductors is a key research goal due to its technological promise. This work presents comprehensive theoretical study ultrathin BaTiO${}_{3}$ on Ge. For the experimentally stable interface stoichiometry, there are two distinct interfacial configurations differing out-of-plane electrical polarizations. The can be made energetically degenerate by choosing an appropriate top electrode, thus enabling, principle, epitaxial...
As the simplest element in nature, unraveling phase diagram of hydrogen is a primary task for condensed matter physics. conjectured many decades ago, low-temperature and high-pressure part diagram, solid expected to become metallic with high superconducting transition temperature. The metallization may occur via band gap closure molecular or atomic solid. Recently, few experimental studies pushed achievable pressures into 400-500 GPa range. There are strong indications that at some pressure...
Metallic transition-metal dichalcogenides (TMDs) are rich material systems in which the interplay between strong electron–electron and electron–phonon interactions often results a variety of collective electronic states, such as charge density waves (CDWs) superconductivity. While most metallic group V TMDs exhibit coexisting superconducting CDW phases, 2H-NbS2 stands out with no ordering. Further, due to interlayer interaction, preparation ultrathin samples has been challenging, limiting...
Recent experimental developments in hydrogen-rich materials at high pressures have put this class of above others the race toward room-temperature superconductivity. As it is basis all class, efforts to determine properties pure solid hydrogen remain intense. Most notably, a recent study metallization identified crystal phase as $C2\text{/}c\text{\ensuremath{-}}24$ molecular up \ensuremath{\sim}425 GPa [Loubeyre et al., Nature (London) 577, 631 (2020)]. It possible that observed caused by...
A recent experimental study of the metallization hydrogen tracked direct band gap and vibron frequency via infrared measurements up to ∼425 GPa (Loubeyreet al(2020Nature577631). Above this pressure, has a discontinuous drop below minimum experimentally accessible energy (∼0.1 eV). The authors suggested that observation is caused by structural phase transition between theC2/c-24 molecular another such asCmca-12. Here, throughab initiocalculations pressure dependent gap, we find data...
Single-layer $\it{h}$-BN is known to have edges with unique magnetism, however, in the commonly fabricated multilayer $\text{AA}^{\prime}$-$\it{h}$-BN, edge relaxations occur that create interlayer bonds and eliminate unpaired electrons at edge. Recently, a robust method of growing unconventional Bernal-stacked (AB-$\it{h}$-BN) has been reported. Here, we use theoretical approaches investigate nitrogen-terminated zigzag AB-$\it{h}$-BN can be formed controlled fashion using high-energy...
A monolayer of ZrO2 has recently been grown on the Si(001) surface and shown to have ferroelectric properties, which signifies realization lowest possible thickness in oxides [M. Dogan et al., Nano Lett. 2018, 18, 241–246]. In our previous computational study, we reported multiple (meta)stable configurations monolayers Si how switching between a pair differently polarized may explain observed behavior these films S. Ismail-Beigi, J. Phys. Chem. C 2019 DOI: 10.1021/acs.jpcc.9b01073]. current...