scholarly journals Investigation of growth characteristics and semimetal–semiconductor transition of polycrystalline bismuth thin films

IUCrJ ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Nan Wang ◽  
Yu-Xiang Dai ◽  
Tian-Lin Wang ◽  
Hua-Zhe Yang ◽  
Yang Qi
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Film Thickness ◽  
Single Crystal ◽  
Growth Characteristics ◽  
Metallic Surface ◽  
Zone Model ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Zone Ii

The preferred orientation growth characteristics and surface roughness of polycrystalline bismuth (Bi) thin films fabricated on glass substrates using the molecular beam epitaxy method were investigated at temperatures ranging from 18 to 150°C. The crystallization and morphology were analyzed in detail and the polycrystalline metal film structure-zone model (SZM) was modified to fit the polycrystalline Bi thin film. The boundary temperature between Zone T and Zone II in the SZM shifted to higher temperatures with the increase in film thickness or the decrease of growth rate. Furthermore, the effect of the thickness and surface roughness on the transport properties was investigated, especially for Bi thin films in Zone II. A two-transport channels model was adopted to reveal the influence of the film thickness on the competition between the metallic surface states and the semiconducting bulk states, which is consistent with the results of Bi single-crystal films. Therefore, the polycrystalline Bi thin films are expected to replace the single-crystal films in the application of spintronic devices.

Epitaxial growth of Cu-Ni Single Crystal Alloys and Multilayers by Molecular Beam Epitaxy

1989 ◽  
Vol 160 ◽  
Author(s):  
R.P. Burns ◽  
Y.H. Lee ◽  
N.R. Parikh ◽  
J.B. Posthill ◽  
M.J. Mantini ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Beam Epitaxy ◽  
Single Crystal ◽  
Epitaxial Growth ◽  
Molecular Beam ◽  
Substrate Material ◽  
High Reactivity ◽  
Lattice Match ◽  
Single Crystal Films ◽  
Crystal Films

AbstractEpitaxial growth of thin films, alloys, and multilayers from the Cu-Ni system are being explored as a means of fabricating a substrate to lattice match diamond. These single crystal films are superior to commercially available substrate material. Due to the high reactivity of the metal surfaces in atmosphere, all processing must be done under UHV conditions. In vacuo preparation, growth, and analysis of the metals is described.

Transport Studies in Single-Crystal Films of Cosi2 and Nisi2

1983 ◽  
Vol 25 ◽  
Author(s):  
J. C. Hensel ◽  
R. T. Tung ◽  
J. M. Poate ◽  
F. C. Unterwald ◽  
D. C. Jacobson
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Transport Studies ◽  
Single Crystal Films ◽  
Crystal Films ◽  
The Difference ◽  
Temperature Resistivity

ABSTRACTTransport studies have been performed on thin films of CoSi 2 and NiSis2 in the temperature range 1 to 300 K. The conductivities are metallic with essentially the same temperature dependence; however, the residual resistivities are markedly different even though the two silicides are structurally similar (the room temperature resistivity of NiSi2 being at least twice that of CoSi2 of 15 μΩ cm). The difference is attributed to intrinsic defects in NiSi2. This defect has been simulated by ion bombardment of the film where it is also shown that Matthiesen's rule is obeyed over a remarkable range of bombardment doses.

Uniform growth of SiC single crystal thin films via a metal–Si alloy flux by vapour–liquid–solid pulsed laser deposition: the possible existence of a precursor liquid flux film

CrystEngComm ◽  
2016 ◽  
Vol 18 (1) ◽  
pp. 143-148 ◽  
Author(s):  
Aomi Onuma ◽  
Shingo Maruyama ◽  
Takeshi Mitani ◽  
Tomohisa Kato ◽  
Hajime Okumura ◽  
...  
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Single Crystal ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Liquid Flux ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Interfacial Behaviour

3C-SiC single crystal films were successfully obtained in the PLD-based VLS process with a Si–Ni liquid flux, the interfacial behaviour of which was investigated by in situ high temperature laser microscopy in vacuum.

Molecular orientation in single crystal thin films of N-(4-nitrophenyl)-(L)-prolinol

1998 ◽  
Vol 13 (1) ◽  
pp. 131-134 ◽  
Author(s):  
Ligui Zhou ◽  
M. Thakur
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Single Crystal ◽  
Molecular Orientation ◽  
Second Harmonic ◽  
Substrate Surface ◽  
X Ray Diffraction ◽  
X Ray ◽  
Single Crystal Films ◽  
Crystal Films

Thin single crystal films of N-(4-nitrophenyl)-(L)-prolinol (NPP) were prepared using the modified shear method. The surface orientation of the single crystal films was determined by x-ray diffraction and was found to be [101]. Polarized microscopy showed uniform birefringence and complete extinction when the thin film was rotated under crossed polarization, implying single crystal thin films with uniform surface were obtained. The molecular orientation in the NPP thin film was studied by polarized UV-visible and polarized micro-FTIR spectroscopy along with x-ray diffraction. The orientation of the NPP molecules was found to be almost parallel to the plane of the film. This parallel orientation is because of the polar (hydrogen bonding) interaction of the −(OH) and the N=O groups of the NPP molecule with the hydrophilic substrate surface. The results of the second harmonic generation (SHG) measurements are consistent with such a molecular orientation. These results show that the final molecular and crystallographic orientation in the film is determined by its initial molecule-substrate interaction.

Copper Diffusion Characteristics in Single Crystal and Polycrystalline TaN

2002 ◽  
Vol 745 ◽  
Author(s):  
H. Wang ◽  
Ashutosh Tiwari ◽  
X. Zhang ◽  
A. Kvit ◽  
J. Narayan
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Buffer Layers ◽  
Laser Deposition ◽  
Barrier Material ◽  
Copper Diffusion ◽  
Diffusion Characteristics ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Z Contrast

ABSTRACTTaN has become a very promising diffusion barrier material for Cu interconnections, due to the high thermal stability requirement and thickness limitation for next generation ULSI devices. TaN has a variety of phases and Cu diffusion characteristics vary with different phases and microstructures. We have investigated the diffusivity of copper in single-crystal (NaCl-structured) and polycrystalline TaN thin films grown by pulsed laser deposition. The polycrystalline TaN films were grown directly on Si(100), while the single crystal films were grown with TiN buffer layers. Both of poly and single-crystal films with Cu overlayers were annealed at 500 °C, 600 °C, 650 °C, and 700 °C in vacuum to study the copper diffusion characteristics. The diffusion of copper into TaN was studied using STEM-Z contrast, where the contrast is proportional to Z (atomic number), and TEM. The diffusion distances are found to be about 5nm at 650°C for 30 min annealing. The diffusivity of Cu into single crystal TaN follows the relation D = (160±9.5)exp[-(3.27 ±0.1)eV/kBT]cm2s-1 in the temperature range of 600°C to 700°C. We observe that Cu diffusion in polycrystalline TaN thin films is nonuniform with enhanced diffusivities along the grain boundary.

Epitaxial growth of very thin films of germanium

1978 ◽  
Vol 36 (1) ◽  
pp. 134-135
Author(s):  
C.W. Hoeike
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Epitaxial Growth ◽  
Vapour Deposition ◽  
Film Growth ◽  
Standard Technique ◽  
Amorphous Film ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Epitaxial Film Growth

The preparation of germanium electron microscopy specimens by chemically polishing slices cut from a single crystal is a standard technique (1). Also, epitaxial growth of germanium on crystalline substrates has been achieved by vapour deposition (2,3). However, the selfsupporting very thin films required for high resolution, crystal lattice imaging experiments cannot be easily prepared by either method.A uniform amorphous film of germanium of any desired thickness can be prepared, however, by vacuum evaporation of germanium from a tungsten basket onto a suitable substrate at any temperature below 500 K. This amorphous film will crystallize when heated to 675 K or more (2). By controlling the heating of the substrate during evaporation and subsequent crystallization, it is possible to induce epitaxial film growth on single crystal substrates.The work described here has established the conditions necessary for the growth of germanium single crystal films 140Å thick, with [111] and [100] surface orientations.

A Theory of Shape-Memory Thin Films with Applications

1996 ◽  
Vol 459 ◽  
Author(s):  
K. Bhattacharya ◽  
R. D. James
Keyword(s):  
Thin Films ◽  
Shape Memory Alloys ◽  
Single Crystal ◽  
Shape Memory ◽  
Large Deformations ◽  
Energy Output ◽  
Shape Memory Material ◽  
Bulk Materials ◽  
Single Crystal Films ◽  
Crystal Films

Shape-memory alloys have the largest energy output per unit volume per cycle of known actuator systems [1]. Unfortunately, they are temperature activated and hence, their frequency is limited in bulk specimens. However, this is overcome in thin films; and hence shape-memory alloys are ideal actuator materials in micromachines[l]. The heart of the shape-memory effect lies in a martensitic phase transformation and the resulting microstructure. It is well-known that microstructure can be significantly different in thin films as compared to bulk materials. In this paper, we report on a theory of single crystal martensitic this films. We show that single crystal films of shape memory material offer interesting possibilities for producing very large deformations, at small scales.

Microstructural instability in single-crystal thin films

1996 ◽  
Vol 11 (6) ◽  
pp. 1470-1482 ◽  
Author(s):  
A. Seifert ◽  
A Vojta ◽  
J. S. Speck ◽  
F. F. Lange
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Morphological Changes ◽  
Current System ◽  
Fluorite Structure ◽  
Free Energy Function ◽  
Stability Diagrams ◽  
Single Crystal Films ◽  
Microstructural Instability ◽  
Crystal Films

Epitaxial PbTiO3 thin films were produced from a mixed Pb–Ti double-alkoxide precursor by spin-coating onto single crystal (001) SrTiO3 substrates. Heat treatment at 800 °C produces a dense and continuous, epitaxial lead titanate film through an intermediate Pb-Ti fluorite structure. A microstructural instability occurred when very thin single crystal films were fabricated; this instability caused the films to become discontinuous. Scanning electron microscopy and atomic force microscopy observations show that single crystal films with a thickness less than ∼80 nm developed holes that expose the substrate; thinner films broke up into isolated, single crystal islands. The walls of the holes were found to be (111) perovskite planes. A free energy function, which considered the anisotropic surface energies of different planes, was developed to describe the microstructural changes in the film and to understand the instability phenomenon. The function predicted that pre-existing holes greater than a critical size are necessary to initiate hole growth, and it predicted the observed morphological changes in the current system. Morphological stability diagrams that explain the stability fields for different film configurations, i.e., either completely covered, with holes, or single crystal islands, can be calculated for any film/substrate system.

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

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