MnBi2Se4-Based Magnetic Modulated Heterostructures

Thin films of magnetic topological insulators (TIs) are expected to exhibit a quantized anomalous Hall effect when the magnetizations on the top and bottom surfaces are parallel and a quantized topological magnetoelectric effect when the magnetizations have opposite orientations. Progress in the observation of these quantum effects was achieved earlier in the films with modulated magnetic doping. On the other hand, the molecular-beam-epitaxy technique allowing the growth of stoichiometric magnetic van der Waals blocks in combination with blocks of topological insulator was developed. This approach should allow the construction of modulated heterostructures with the desired architecture. In the present paper, based on the first-principles calculations, we study the electronic structure of symmetric thin film heterostructures composed of magnetic MnBi2Se4 blocks (septuple layers, SLs) and blocks of Bi2Se3 TI (quintuple layers, QLs) in dependence on the depth of the magnetic SLs relative to the film surface and the TI spacer between them. Among considered heterostructures we have revealed those characterized by nontrivial band topology.

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Laser Assisted Molecular Beam Deposition of Thin Films for Gate Dielectrics Applications

MRS Proceedings ◽

10.1557/proc-768-g3.16 ◽

2003 ◽

Vol 768 ◽

Author(s):

Robert L. DeLeon ◽

James F. Garvey ◽

Gary S. Tompa ◽

Richard Moore ◽

Harry Efstathiadis

Keyword(s):

Thin Film ◽

Thin Films ◽

Dielectric Constant ◽

Molecular Beam ◽

High Dielectric Constant ◽

Film Surface ◽

Rutherford Back Scattering ◽

Molecular Beam Deposition ◽

High Dielectric ◽

Beam Deposition

AbstractHigh dielectric constant (k), the thermal stability and the chemical stability with respect to reaction with silicon of hafnium oxide (HfO2), and zirconium oxide (ZrO2) places them among the leading candidates for an alternative gate dielectric material. High dielectric constant HfO2 and ZrO2 thin films have successfully been deposited on silicon substrates at a temperature of 27 °C by Laser Assisted Molecular Beam Deposition (LAMBD). The LAMBD process is related to conventional Pulsed Laser Deposition (PLD). In the PLD process, the ablation plume impinges directly upon the substrate to deposit the thin film, whereas in the LAMBD process, the ablation material is expanded within a concurrently pulsed stream of a reactive gas. The gas pulse serves both to create the desired material and to transport the material to the substrate for deposition of the thin film. One advantage of the LAMBD process is that a chemically reactive carrier gas can be selected to produce the desired chemical products. Depositions yielded 35 nm to 135 nm thick HfO2, and ZrO2 films.Structural and chemical characterization of the films were performed by Auger electron spectroscopy (AES), Rutherford back-scattering (RBS), scanning electron microscopy (SEM), and x-ray diffraction (XRD). Film surface was investigated by atomic force microscopy (AFM) while optical characterization was also performed by means of spectroscopic ellipsometry (SE). Within the process window investigated, the film Hf/O and Zr/O ratios was found to be in the range 0.6 to 1.2. The as deposited films were amorphous with refraction index (RI) at 623 nm wavelength films in the range of 1.22 to 1.27 for the HfO2 and in the range of 1.23 to 1.19 for the ZrO2 films.

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Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

10.26434/chemrxiv.8052218.v3 ◽

2019 ◽

Author(s):

Henrik Pedersen ◽

Björn Alling ◽

Hans Högberg ◽

Annop Ektarawong

Keyword(s):

Thin Films ◽

Thermodynamic Stability ◽

First Principles ◽

Thermal Equilibrium ◽

Density Functional ◽

Van Der Waals ◽

Chemical Vapor ◽

First Principles Calculations ◽

Functional Theory ◽

The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

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Interface-induced sign reversal of the anomalous Hall effect in magnetic topological insulator heterostructures

Nature Communications ◽

10.1038/s41467-020-20349-z ◽

2021 ◽

Vol 12 (1) ◽

Cited By ~ 1

Author(s):

Fei Wang ◽

Xuepeng Wang ◽

Yi-Fan Zhao ◽

Di Xiao ◽

Ling-Jie Zhou ◽

...

Keyword(s):

Hall Effect ◽

Electric Fields ◽

First Principles ◽

Berry Phase ◽

Condensed Matter ◽

Anomalous Hall Effect ◽

First Principles Calculations ◽

Sign Reversal ◽

Berry Curvature ◽

Topological Materials

AbstractThe Berry phase picture provides important insights into the electronic properties of condensed matter systems. The intrinsic anomalous Hall (AH) effect can be understood as the consequence of non-zero Berry curvature in momentum space. Here, we fabricate TI/magnetic TI heterostructures and find that the sign of the AH effect in the magnetic TI layer can be changed from being positive to negative with increasing the thickness of the top TI layer. Our first-principles calculations show that the built-in electric fields at the TI/magnetic TI interface influence the band structure of the magnetic TI layer, and thus lead to a reconstruction of the Berry curvature in the heterostructure samples. Based on the interface-induced AH effect with a negative sign in TI/V-doped TI bilayer structures, we create an artificial “topological Hall effect”-like feature in the Hall trace of the V-doped TI/TI/Cr-doped TI sandwich heterostructures. Our study provides a new route to create the Berry curvature change in magnetic topological materials that may lead to potential technological applications.

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Tailoring the anomalous Hall effect of SrRuO3 thin films by strain: A first principles study

Journal of Applied Physics ◽

10.1063/5.0043742 ◽

2021 ◽

Vol 129 (9) ◽

pp. 093904

Author(s):

Kartik Samanta ◽

Marjana Ležaić ◽

Stefan Blügel ◽

Yuriy Mokrousov

Keyword(s):

Thin Films ◽

Hall Effect ◽

First Principles ◽

Anomalous Hall Effect ◽

First Principles Study

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Exotic Doping for Zno Thin Films: Possibility of Monolithic Optical Integrated Circuit

MRS Proceedings ◽

10.1557/proc-574-317 ◽

1999 ◽

Vol 574 ◽

Cited By ~ 7

Author(s):

Norifumi Fujimura ◽

Tamaki Shimura ◽

Toshifumi Wakano ◽

Atsushi Ashida ◽

Taichiro Ito

Keyword(s):

Thin Film ◽

Thin Films ◽

Nonlinear Optic ◽

Integrated Circuit ◽

Film Surface ◽

Zno Thin Films ◽

Process Window ◽

Electro Optic ◽

Film Substrate ◽

Optical Integrated Circuit

AbstractWe propose the application of ZnO:X (X = Li, Mg, N, In, Al, Mn, Gd, Yb etc.) films for a monolithic Optical Integrated Circuit (OIC). Since ZnO exhibits excellent piezoelectric effect and has also electro-optic and nonlinear optic effects and the thin films are easily obtained, it has been studied as one of the important thin film wave guide materials especially for an acoustooptic device[1]. In terms of electro-optic and nonlinear optic effects, however, LiNbO3 or LiTaO3 is superior to ZnO. The most important issue of thin film waveguide using such ferroelectrics is optical losses at the film/substrate interface and the film surface, because the process window to control the surface morphology is very narrow due to their high deposition temperature. Since ZnO can be grown at extremely low temperature, the roughness at the surface and the interface is expected to be minimized. This is the absolute requirement especially for waveguide using a blue or ultraviolet laser. Recently, lasing at the wavelength of ultraviolet, ferroelectric and antiferromagnetic behaviors of ZnO doped with various exotic elements (exotic doping) have been reported. This paper discusses the OIC application of ZnO thin films doped with exotic elements.

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Development of the Structural, Optical, and Electrical Properties of PEDOT:PSS Conducting Polymer Thin Film for Energy Applications

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.902.65 ◽

2021 ◽

Vol 902 ◽

pp. 65-70

Author(s):

Samar Aboulhadeed ◽

Mohsen Ghali ◽

Mohamad M. Ayad

Keyword(s):

Thin Film ◽

Thin Films ◽

Electrical Properties ◽

Conducting Polymer ◽

Film Surface ◽

Volume Ratio ◽

Transport Layer ◽

Electron Transport Layer ◽

Optical And Electrical Properties ◽

Energy Applications

We report on a development of the structural, optical and electrical properties of poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT:PSS) conducting polymer thin films. The PEDOT:PSS thin films were deposited by a controlled thin film applicator and their physical properties were found to be effectively modified by isopropanol. The deposited films were investigated by several techniques including XRD, UV–Vis, SPM and Hall-effect. Interestingly, by optimizing the PEDOTS:PSS/ISO volume ratio (v:v), we find that the film charge carriers type can be switched from p to n-type with a high bulk carriers concentration reaching 6×1017 cm-3. Moreover, the film surface roughness becomes smoother and reaching a small value of only 1.9 nm. Such development of the PEDOT:PSS film properties makes it very promising to act as an electron transport layer for different energy applications.

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Study on preparing PLT(28) thin film and its electro-optic effect

Journal of Materials Research ◽

10.1557/jmr.1998.0181 ◽

1998 ◽

Vol 13 (5) ◽

pp. 1266-1270 ◽

Cited By ~ 12

Author(s):

Ai-Li Ding ◽

Wei-Gen Luo ◽

P. S. Qiu ◽

J. W. Feng ◽

R. T. Zhang

Keyword(s):

Thin Film ◽

Thin Films ◽

Magnetron Sputtering ◽

Faraday Effect ◽

The Other ◽

Ceramic Powders ◽

Glass Substrates ◽

Annealing Conditions ◽

Electro Optic

PLT(28) thin films deposited on glass substrates were studied by two sputtering processes. One is an in situ magnetron sputtering and the other is a low-temperature magnetron sputtering. The sintered PLT ceramic powders are used as a sputtering target for both processes. The influences of sputtering and annealing conditions on structure and crystallinity of the films were investigated. The electro-optic (E-O) properties of PLT(28) thin films prepared by the two processes were determined by a technique according to Faraday effect. The researches showed the E-O properties were strongly affected by the sputtering process. The film with larger grains exhibits stronger E-O effect. The quadratic E-O coefficient of PLT(28) thin film varies in the range of 0.1 × 10−16 to 1.0 × 10−16 (m/v)2.

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Initial stages of the adsorption of Sc and ScN thin films on GaN(0001): First principles calculations

Applied Surface Science ◽

10.1016/j.apsusc.2012.11.094 ◽

2013 ◽

Vol 268 ◽

pp. 16-21 ◽

Cited By ~ 9

Author(s):

J. Guerrero-Sánchez ◽

Gregorio H. Cocoletzi ◽

J.F. Rivas-Silva ◽

Noboru Takeuchi

Keyword(s):

Thin Films ◽

First Principles ◽

First Principles Calculations

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Positioning of the Precursor Gas Inlet in an Atmospheric Dielectric Barrier Reactor, and its Effect on the Quality of Deposited TiOx Thin Film Surface

Acta Polytechnica ◽

10.14311/1767 ◽

2013 ◽

Vol 53 (2) ◽

Author(s):

Jan Píchal ◽

Julia Klenko

Keyword(s):

Thin Film ◽

Thin Films ◽

Dielectric Barrier Discharge ◽

Atmospheric Pressure ◽

Barrier Discharge ◽

Film Surface ◽

Dielectric Barrier ◽

Thin Film Surface ◽

Atmospheric Dielectric Barrier Discharge

Thin film technology has become pervasive in many applications in recent years, but it remains difficult to select the best deposition technique. A further consideration is that, due to ecological demands, we are forced to search for environmentally benign methods. One such method might be the application of cold plasmas, and there has already been a rapid growth in studies of cold plasma techniques. Plasma technologies operating at atmospheric pressure have been attracting increasing attention. The easiest way to obtain low temperature plasma at atmospheric pressure seems to be through atmospheric dielectric barrier discharge (ADBD). We used the plasma enhanced chemical vapour deposition (PECVD) method applying atmospheric dielectric barrier discharge (ADBD) plasmafor TiOx thin films deposition, employing titanium isopropoxide (TTIP) and oxygen as reactants, and argon as a working gas. ADBD was operated in filamentary mode. The films were deposited on glass. We studied the quality of the deposited TiOx thin film surface for various precursor gas inlet positions in the ADBD reactor. The best thin films quality was achieved when the precursor gases were brought close to the substrate surface directly through the inlet placed in one of the electrodes.High hydrophilicity of the samples was proved by contact angle tests (CA). The film morphology was tested by atomic force microscopy (AFM). The thickness of the thin films varied in the range of (80 ÷ 210) nm in dependence on the composition of the reactor atmosphere. XPS analyses indicate that composition of the films is more like the composition of TiOxCy.

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Effect of RF Power on the Properties of Sputtered-CuS Thin Films for Photovoltaic Applications

Energies ◽

10.3390/en13030688 ◽

2020 ◽

Vol 13 (3) ◽

pp. 688 ◽

Cited By ~ 1

Author(s):

Donghyeok Shin ◽

SangWoon Lee ◽

Dong Ryeol Kim ◽

Joo Hyung Park ◽

Yangdo Kim ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Binding Energy ◽

Indium Tin Oxide ◽

Short Circuit ◽

Film Surface ◽

Binding Energies ◽

Tin Sulfide ◽

Rf Power ◽

Deposition Power

Copper sulfide (CuS) thin films were deposited on a glass substrate at room temperature using the radio-frequency (RF) magnetron-sputtering method at RF powers in the range of 40–100 W, and the structural and optical properties of the CuS thin film were investigated. The CuS thin films fabricated at varying deposition powers all exhibited hexagonal crystalline structures and preferred growth orientation of the (110) plane. Raman spectra revealed a primary sharp and intense peak at the 474 cm−1 frequency, and a relatively wide peak was found at 265 cm−1 frequency. In the CuS thin film deposited at an RF power of 40 W, relatively small dense particles with small void spacing formed a smooth thin-film surface. As the power increased, it was observed that grain size and grain-boundary spacing increased in order. The binding energy peaks of Cu 2p3/2 and Cu 2p1/2 were observed at 932.1 and 952.0 eV, respectively. Regardless of deposition power, the difference in the Cu2+ state binding energies for all the CuS thin films was equivalent at 19.9 eV. We observed the binding energy peaks of S 2p3/2 and S 2p1/2 corresponding to the S2− state at 162.2 and 163.2 eV, respectively. The transmittance and band-gap energy in the visible spectral range showed decreasing trends as deposition power increased. For the CuS/tin sulfide (SnS) absorber-layer-based solar cell (glass/Mo/absorber(CuS/SnS)/cadmium sulfide (CdS)/intrinsic zinc oxide (i-ZnO)/indium tin oxide (ITO)/aluminum (Al)) with a stacked structure of SnS thin films on top of the CuS layer deposited at 100 W RF power, an open-circuit voltage (Voc) of 115 mA, short circuit current density (Jsc) of 9.81 mA/cm2, fill factor (FF) of 35%, and highest power conversion efficiency (PCE) of 0.39% were recorded.

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