scholarly journals Honeycomb Lattice in Metal-Rich Chalcogenide Fe2Te

2021 ◽  
Vol 38 (11) ◽  
pp. 116801
Author(s):  
Jia-Qi Guan ◽  
Li Wang ◽  
Pengdong Wang ◽  
Wei Ren ◽  
Shuai Lu ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Electronic Devices ◽  
Growth Conditions ◽  
Photoemission Spectroscopy ◽  
Scanning Tunneling ◽  
Honeycomb Lattice ◽  
Tunneling Microscopy ◽  
Limited Growth ◽  
Structural Morphology ◽  
Angle Resolved Photoemission Spectroscopy

Two-dimensional honeycomb crystals have inspired intense research interest for their novel properties and great potential in electronics and optoelectronics. Here, through molecular beam epitaxy on SrTiO3(001), we report successful epitaxial growth of metal-rich chalcogenide Fe2Te, a honeycomb-structured film that has no direct bulk analogue, under Te-limited growth conditions. The structural morphology and electronic properties of Fe2Te are explored with scanning tunneling microscopy and angle resolved photoemission spectroscopy, which reveal electronic bands cross the Fermi level and nearly flat bands. Moreover, we find a weak interfacial interaction between Fe2Te and the underlying substrates, paving a newly developed alternative avenue for honeycomb-based electronic devices.

scholarly journals Kekulene: On-Surface Synthesis, Orbital Structure, and Aromatic Stabilization

2020 ◽  
Author(s):  
Anja Haags ◽  
Alexander Reichmann ◽  
Qitang Fan ◽  
Larissa Egger ◽  
Hans Kirschner ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Photoemission Spectroscopy ◽  
Scanning Tunneling ◽  
Orbital Structure ◽  
Tunneling Microscopy ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Highest Occupied Molecular Orbital ◽  
Shed Light ◽  
Aromatic Stabilization

We revisit the question of kekulene’s aromaticity by focusing on the electronic structure of its frontier orbitals as determined by angle-resolved photoemission spectroscopy. To this end, we have developed a specially designed precursor, 1,4,7(2,7)-triphenanthrenacyclononaphane-2,5,8-triene, which allows us to prepare sufficient quantities of kekulene of high purity directly on a Cu(111) surface, as confirmed by scanning tunneling microscopy. Supported by density functional calculations, we determine the orbital structure of kekulene’s highest occupied molecular orbital by photoelectron tomography. In agreement with a recent aromaticity assessment of kekulene based solely on C–C bond lengths, we conclude that the π-conjugation of kekulene is better described by the Clar model rather than a superaromatic model. Thus, by exploiting the capabilities of photoemission tomography, we shed light on the question which consequences aromaticity holds for the frontier electronic structure of a π-conjugated molecule.<br>

AFM and STM Studies of Large Scale Unstable Growth Formed During GaAs (001) Homoepitaxy

1994 ◽  
Vol 340 ◽  
Author(s):  
C. Orme ◽  
M.D. Johnson ◽  
K.T. Leung ◽  
B.G. Orr
Keyword(s):  
Molecular Beam Epitaxy ◽  
Scanning Tunneling Microscopy ◽  
Large Scale ◽  
Molecular Beam ◽  
Growth Conditions ◽  
Growth Mode ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Island Nucleation ◽  
Atomic Force

ABSTRACTAtomic force and scanning tunneling microscopy studies have been performed on GaAs(001) films grown by molecular beam epitaxy. Multilayered mounds are seen to evolve when the growth conditions favor island nucleation. As the epilayer thickness is increased, these features grow in all dimensions but the angle of inclination remains approximately constant at 1°. The mounding does not occur on surfaces grown in stepflow. We propose that the multi-layered features are due to an unstable growth mode which relies on island nucleation and the presence of a step edge barrier.

scholarly journals Flat epitaxial quasi-1D phosphorene chains

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wei Zhang ◽  
Hanna Enriquez ◽  
Yongfeng Tong ◽  
Andrew J. Mayne ◽  
Azzedine Bendounan ◽  
...  
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Photoemission Spectroscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Functional Theory ◽  
Precise Control ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Room Temperature Magnetism ◽  
Topological Phase Transitions

AbstractThe emergence of peculiar phenomena in 1D phosphorene chains (P chains) has been proposed in theoretical studies, notably the Stark and Seebeck effects, room temperature magnetism, and topological phase transitions. Attempts so far to fabricate P chains, using the top-down approach starting from a few layers of bulk black phosphorus, have failed to produce reliably precise control of P chains. We show that molecular beam epitaxy gives a controllable bottom-up approach to grow atomically thin, crystalline 1D flat P chains on a Ag(111) substrate. Scanning tunneling microscopy, angle-resolved photoemission spectroscopy, and density functional theory calculations reveal that the armchair-shaped chains are semiconducting with an intrinsic 1.80 ± 0.20 eV band gap. This could make these P chains an ideal material for opto-electronic devices.

scholarly journals Kekulene: On-Surface Synthesis, Orbital Structure, and Aromatic Stabilization

2020 ◽  
Author(s):  
Anja Haags ◽  
Alexander Reichmann ◽  
Qitang Fan ◽  
Larissa Egger ◽  
Hans Kirschner ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Photoemission Spectroscopy ◽  
Scanning Tunneling ◽  
Orbital Structure ◽  
Tunneling Microscopy ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Highest Occupied Molecular Orbital ◽  
Shed Light ◽  
Aromatic Stabilization

We revisit the question of kekulene’s aromaticity by focusing on the electronic structure of its frontier orbitals as determined by angle-resolved photoemission spectroscopy. To this end, we have developed a specially designed precursor, 1,4,7(2,7)-triphenanthrenacyclononaphane-2,5,8-triene, which allows us to prepare sufficient quantities of kekulene of high purity directly on a Cu(111) surface, as confirmed by scanning tunneling microscopy. Supported by density functional calculations, we determine the orbital structure of kekulene’s highest occupied molecular orbital by photoelectron tomography. In agreement with a recent aromaticity assessment of kekulene based solely on C–C bond lengths, we conclude that the π-conjugation of kekulene is better described by the Clar model rather than a superaromatic model. Thus, by exploiting the capabilities of photoemission tomography, we shed light on the question which consequences aromaticity holds for the frontier electronic structure of a π-conjugated molecule.<br>

STM studies of crystal growth

1991 ◽  
Vol 49 ◽  
pp. 374-375
Author(s):  
M. G. Lagally
Keyword(s):  
Crystal Growth ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
Sputter Deposition ◽  
Field Of View ◽  
Scanning Tunneling ◽  
Wide Field ◽  
Tunneling Microscopy ◽  
Wide Field Of View ◽  
The One

It has been recognized since the earliest days of crystal growth that kinetic processes of all Kinds control the nature of the growth. As the technology of crystal growth has become ever more refined, with the advent of such atomistic processes as molecular beam epitaxy, chemical vapor deposition, sputter deposition, and plasma enhanced techniques for the creation of “crystals” as little as one or a few atomic layers thick, multilayer structures, and novel materials combinations, the need to understand the mechanisms controlling the growth process is becoming more critical. Unfortunately, available techniques have not lent themselves well to obtaining a truly microscopic picture of such processes. Because of its atomic resolution on the one hand, and the achievable wide field of view on the other (of the order of micrometers) scanning tunneling microscopy (STM) gives us this opportunity. In this talk, we briefly review the types of growth kinetics measurements that can be made using STM. The use of STM for studies of kinetics is one of the more recent applications of what is itself still a very young field.

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