scholarly journals Epitaxial Growth and Structural Characterizations of MnBi2Te4 Thin Films in Nanoscale

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3322
Author(s):  
Shu-Hsuan Su ◽  
Jen-Te Chang ◽  
Pei-Yu Chuang ◽  
Ming-Chieh Tsai ◽  
Yu-Wei Peng ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Topological Insulator ◽  
Quantum Interference ◽  
Growth Parameters ◽  
Magnetic Measurement ◽  
Magnetic Hysteresis ◽  
Flux Ratio ◽  
Growth Surface ◽  
Antiferromagnetic Order ◽  
Device Applications

The intrinsic magnetic topological insulator MnBi2Te4 has attracted much attention due to its special magnetic and topological properties. To date, most reports have focused on bulk or flake samples. For material integration and device applications, the epitaxial growth of MnBi2Te4 film in nanoscale is more important but challenging. Here, we report the growth of self-regulated MnBi2Te4 films by the molecular beam epitaxy. By tuning the substrate temperature to the optimal temperature for the growth surface, the stoichiometry of MnBi2Te4 becomes sensitive to the Mn/Bi flux ratio. Excessive and deficient Mn resulted in the formation of a MnTe and Bi2Te3 phase, respectively. The magnetic measurement of the 7 SL MnBi2Te4 film probed by the superconducting quantum interference device (SQUID) shows that the antiferromagnetic order occurring at the Néel temperature 22 K is accompanied by an anomalous magnetic hysteresis loop along the c-axis. The band structure measured by angle-resolved photoemission spectroscopy (ARPES) at 80 K reveals a Dirac-like surface state, which indicates that MnBi2Te4 has topological insulator properties in the paramagnetic phase. Our work demonstrates the key growth parameters for the design and optimization of the synthesis of nanoscale MnBi2Te4 films, which are of great significance for fundamental research and device applications involving antiferromagnetic topological insulators.

scholarly journals Молекулярно-пучковая эпитаксия двухмерных слоев GaSe на подложках GaAs(001) и GaAs(112): структурные и оптические свойства

2019 ◽  
Vol 53 (8) ◽  
pp. 1152
Author(s):  
С.В. Сорокин ◽  
П.С. Авдиенко ◽  
И.В. Седова ◽  
Д.А. Кириленко ◽  
М.А. Яговкина ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Flux Ratio ◽  
Growth Surface ◽  
X Ray Diffraction ◽  
Mbe Growth ◽  
Transmission Electron ◽  
Electron Diffraction Technique ◽  
Flux Intensity ◽  
High Enrichment ◽  
Means Of Transmission

AbstractThe results of studies of the structural and optical properties of two-dimensional GaSe layers grown by molecular-beam epitaxy on GaAs(001) and GaAs(112) substrates using a valve cracking cell for the Se source are reported. The influence of the MBE growth parameters (the substrate temperature, Ga flux intensity, Se/Ga incident flux ratio) on the surface morphology of the layers is studied. By means of transmission electron microscopy, electron diffraction technique, and Raman spectroscopy, it is shown that the structure of the GaSe layers corresponds to the γ-GaSe polytype. From X-ray diffraction analysis, it is established that there exist α-Ga_2Se_3 inclusions in the GaSe layers grown under conditions of high enrichment of the growth surface with Se.

Growth of GaInNAs by Plasma Assisted Molecular Beam Epitaxy

2000 ◽  
Vol 618 ◽  
Author(s):  
David W. Gotthold ◽  
Sridhar Govindaraju ◽  
Archie L. Holmes ◽  
Ben G. Streetman
Keyword(s):  
Gas Flow ◽  
Growth Parameters ◽  
Optoelectronic Device ◽  
Operating Conditions ◽  
Inert Gas ◽  
Growth Surface ◽  
Active Nitrogen ◽  
Device Applications ◽  
Nitrogen Ratio ◽  
Gas Dilution

ABSTRACTThe nitrogen containing alloy GaInNAs has attracted a great deal of interest recently for optoelectronic device applications at long wavelengths, especially 1.3µm, on GaAs substrates. What has been observed is that the material quality degrades rapidly with the addition of nitrogen. In this work we systematically explore the parameter space for the growth of GainNAs using plasma-assisted MBE and inert gas dilution. Inert gas dilution allows additional control of the production of active nitrogen; thus we can independently adjust RF power, gas flow rate, and nitrogen generation, which is used to study the effects of the plasma on the growth surface. In addition to examining the effects of plasma operating conditions, we will also explore the effects of other growth parameters (arsenic to nitrogen ratio and growth temperature) on the resultant structural and optical properties. These properties will be explored by photoluminescence, SIMS, and x-ray diffraction with the goal of understanding how nitrogen incorporation affects the resultant material properties. The resulting information is used to grow high quality layers for GaNAs avalanche photodiodes with a cut-off wavelength of 1.064µm

scholarly journals A Review on Metamaterials for Device Applications

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 518
Author(s):  
N. Suresh Kumar ◽  
K. Chandra Babu Naidu ◽  
Prasun Banerjee ◽  
T. Anil Babu ◽  
B. Venkata Shiva Reddy
Keyword(s):  
Quantum Interference ◽  
Effective Properties ◽  
Photonic Devices ◽  
Vital Role ◽  
Major Type ◽  
Electric Permittivity ◽  
Superconducting Quantum Interference Devices ◽  
Device Applications ◽  
Microwave Sensors

Metamaterials are the major type of artificially engineered materials which exhibit naturally unobtainable properties according to how their microarchitectures are engineered. Owing to their unique and controllable effective properties, including electric permittivity and magnetic permeability, the metamaterials play a vital role in the development of meta-devices. Therefore, the recent research has mainly focused on shifting towards achieving tunable, switchable, nonlinear, and sensing functionalities. In this review, we summarize the recent progress in terahertz, microwave electromagnetic, and photonic metamaterials, and their applications. The review also encompasses the role of metamaterials in the advancement of microwave sensors, photonic devices, antennas, energy harvesting, and superconducting quantum interference devices (SQUIDs).

scholarly journals Adjustable Quantum Interference Oscillations in Sb-Doped Bi2Se3 Topological Insulator Nanoribbons

ACS Nano ◽  
2020 ◽  
Vol 14 (10) ◽  
pp. 14118-14125
Author(s):  
Hong-Seok Kim ◽  
Tae-Ha Hwang ◽  
Nam-Hee Kim ◽  
Yasen Hou ◽  
Dong Yu ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Quantum Interference ◽  
Interference Oscillations

scholarly journals Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Sophie Charpentier ◽  
Luca Galletti ◽  
Gunta Kunakova ◽  
Riccardo Arpaia ◽  
Yuxin Song ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Topological Insulator ◽  
Quantum Interference ◽  
Order Parameter ◽  
Thermal Strain ◽  
Surface States ◽  
Field Pattern ◽  
Key Factors ◽  
Ordered Phases ◽  
Simultaneous Existence

Abstract Topological superconductivity is central to a variety of novel phenomena involving the interplay between topologically ordered phases and broken-symmetry states. The key ingredient is an unconventional order parameter, with an orbital component containing a chiral p x  + ip y wave term. Here we present phase-sensitive measurements, based on the quantum interference in nanoscale Josephson junctions, realized by using Bi2Te3 topological insulator. We demonstrate that the induced superconductivity is unconventional and consistent with a sign-changing order parameter, such as a chiral p x  + ip y component. The magnetic field pattern of the junctions shows a dip at zero externally applied magnetic field, which is an incontrovertible signature of the simultaneous existence of 0 and π coupling within the junction, inherent to a non trivial order parameter phase. The nano-textured morphology of the Bi2Te3 flakes, and the dramatic role played by thermal strain are the surprising key factors for the display of an unconventional induced order parameter.

Epitaxial growth of the topological insulator Bi2Se3 on Si(111): Growth mode, lattice parameter, and strain state

2013 ◽  
Vol 103 (11) ◽  
pp. 111909 ◽  
Author(s):  
M. Vyshnepolsky ◽  
C. Klein ◽  
F. Klasing ◽  
A. Hanisch-Blicharski ◽  
M. Horn-von Hoegen
Keyword(s):  
Epitaxial Growth ◽  
Topological Insulator ◽  
Strain State ◽  
Lattice Parameter ◽  
Growth Mode

Epitaxial Growth of Ferroelectric Thin Films on GaAs with MgO Buffer Layers by Pulsed Laser Deposition

1991 ◽  
Vol 243 ◽  
Author(s):  
K. Nashimoto ◽  
D. K. Fork ◽  
F. A. Ponce ◽  
T. H. Geballe
Keyword(s):  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Epitaxial Growth ◽  
Pulsed Laser ◽  
Ferroelectric Thin Films ◽  
Buffer Layers ◽  
Laser Deposition ◽  
Hrtem Observation ◽  
Device Applications ◽  
Ferroelectric Hysteresis

AbstractEpitaxial growth of ferroelectric thin films on GaAs (100) by pulsed laser deposition was examined for integrated electro-optic device applications. To promote epitaxy of ferroelectrics and prevent interdiffusion, we have deposited several types of buffer layers. CeO2 reacted strongly with GaAs. Although Y203 9% stabilized-ZrO2 films showed epitaxial growth, YSZ reacted with GaAs at 780°C. MgO grew epitaxially and was stable even at 780°C. HRTEM observation showed a sharp interface between MgO and GaAs. BaTiO3 and SrTiO3 deposited on MgO/GaAs structures showed epitaxial growth. In-plane orientation was BaTiO3 [100 // MgO [100] // GaAs [100]. Epitaxial BaTiO3 films were c-axis oriented tetragonal phase and showed ferroelectric hysteresis.

Influence of Substrate Preparation and Epitaxial Growth Parameters on the Dislocation Densities in 4H-SiC Epitaxial Layers

2008 ◽  
Vol 600-603 ◽  
pp. 143-146 ◽  
Author(s):  
Birgit Kallinger ◽  
Bernd Thomas ◽  
Jochen Friedrich
Keyword(s):  
Epitaxial Growth ◽  
Growth Parameters ◽  
Epitaxial Layers ◽  
Substrate Preparation ◽  
Bipolar Devices ◽  
Dislocation Densities ◽  
Influence Of Substrate ◽  
Device Operation ◽  
Preparation Techniques

Basal Plane Dislocations (BPD) in SiC are thought to cause degradation of bipolar devices as they can trigger the formation and expansion of stacking faults during device operation. Therefore, epilayers without any BPD are strongly recommended for the achievement of long-term reliable bipolar devices. Such epilayers can be achieved by supporting the conversion of BPD into Threading Dislocations (TD), which depends on the epitaxial growth mode (as described in literature). In this work, the influence of several pre-treatments of the SiC substrate prior to epitaxial growth and different epitaxial growth parameters on the reduction of the BPDs in the SiC epilayers was investigated on 4° off-axis substrates. The dislocation content in substrates and epilayers was determined by Defect Selective Etching (DSE) in molten KOH. The averaged BPD density in epitaxial layers can be reduced to < 100 cm-2 for substrate preparation techniques and to < 30 cm-2 for well-suited epitaxial growth parameters. A certain combination of epitaxial growth parameters leads to < 3 BPD/cm2 in the epitaxial layer.

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