The use of NiMnSb Heusler alloy in MBE Grown Tunnel Junction

2001 ◽  
Vol 690 ◽  
Author(s):  
Pascal Turban ◽  
Stéphane Andrieu ◽  
Alberto Tagliaferri ◽  
Céline De Nadai ◽  
Nike Brookes
Keyword(s):  
Electronic Properties ◽  
Growth Process ◽  
Room Temperature ◽  
Molecular Beam ◽  
Magnetic Circular Dichroism ◽  
Growth Conditions ◽  
Photoemission Spectroscopy ◽  
Structural Quality ◽  
X Ray

ABSTRACTIn this paper, the structural, magnetic and electronic properties of single-crystalline NiMnSb thin films grown by molecular beam epitaxy are presented. The growth process and surface morphology were studied by RHEED and STM. The structural quality of the films was investigated by EXAFS and HRTEM. For the optimized growth conditions, the expected NiMnSb C1b structure was obtained. Moreover, the most stable surface was found to be 4x1 reconstructed. The magnetic and electronic properties were studied by X-ray magnetic circular dichroïsm and spin-resolved x-ray photoemission spectroscopy experiments. The magnetization was observed to be essentially due to Mn, in agreement with theory. The surface was not found to be fully polarized but a polarization near 50% at room temperature was observed. Finally, the preparation of fully epitaxial NiMnSb/MgO/NiMnSb(001) trilayers is presented.

Fabrication and characterization of ZnMgO nanowalls grown on 4H-SiC by molecular beam epitaxy

2019 ◽  
Vol 52 (1) ◽  
pp. 168-170
Author(s):  
Mieczyslaw A. Pietrzyk ◽  
Aleksandra Wierzbicka ◽  
Marcin Stachowicz ◽  
Dawid Jarosz ◽  
Adrian Kozanecki
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Optoelectronic Devices ◽  
Growth Conditions ◽  
Buffer Layers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fabrication And Characterization

Control of nanostructure growth is a prerequisite for the development of electronic and optoelectronic devices. This paper reports the growth conditions and structural properties of ZnMgO nanowalls grown on the Si face of 4H-SiC substrates by molecular beam epitaxy without catalysts and buffer layers. Images from scanning electron microscopy revealed that the ZnMgO nanowalls are arranged in parallel rows following the stripe morphology of the SiC surface, and their thickness is around 15 nm. The crystal quality of the structures was evaluated by X-ray diffraction measurements.

Characterization of CdTe:Zn:V crystals grown under microgravity conditions

2002 ◽  
Vol 17 (12) ◽  
pp. 3037-3041 ◽  
Author(s):  
V. Corregidor ◽  
V. Babentsov ◽  
J. L. Castaño ◽  
M. Fiederle ◽  
T. Feltgen ◽  
...  
Keyword(s):  
Growth Process ◽  
Structural Quality ◽  
Seed Region ◽  
Photoluminescence Spectra ◽  
Positive Role ◽  
X Ray ◽  
Microgravity Conditions

CdTe:Zn:V crystals grown by the seeded Bridgman method in microgravity conditions during the STS95-Spacelab-AGHF-1 mission and in the ground laboratory (l-g) were analyzed and compared. The results obtained clearly show that the structural quality of the space crystal is better. Density of inclusions, concentration of dislocations, and presence of stresses are lower in the microgravity-grown (μ-g) crystal. The l-g crystal contains twins and grains from the beginning of the growth process, that is, from the near-seed region. In general, the concentration of inclusions and amount of segregated impurities on the l-g crystal are larger than in the μ-g crystal. X-ray rocking curves and low-temperature photoluminescence spectra demonstrate the relatively high quality of both crystals on a microscale at the beginning of the growth and show that the l-g conditions were worse at the end. The results of this investigation demonstrate a positive role of contactless growth and μ-g conditions in the melt in suppressing the creation of inclusions and dislocations.

Non-Polar GaN/AlN Superlattices on A-plane AlN (500nm) Buffer Layers Grown by RF-MBE

2004 ◽  
Vol 831 ◽  
Author(s):  
Takayuki Morita ◽  
Akihiko Kikuchi ◽  
Katsumi Kishino
Keyword(s):  
Molecular Beam ◽  
Growth Conditions ◽  
Buffer Layers ◽  
Structural Quality ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sapphire Substrates ◽  
Frequency Plasma ◽  
Diffraction Peaks ◽  
Rich Side

ABSTRACTThe growth conditions of A-plane AlN and GaN epitaxial layers by radio-frequency plasma assisted molecular beam epitaxy on R-plane sapphire substrates were investigated. The growth temperature and V/III supply ratio dependency on structural quality and surface roughness was described. The optimum V/III ratio for A-plane GaN and AlN layers was shifted to nitrogen rich side compared to the C-plane layers. A-plane GaN/AlN superlattices (SLs) were also grown on R-plane sapphire substrates. The X-ray diffraction peaks from a primary and a 1st satellite were observed. From a comparison of low temperature photoluminescence peak wavelength between A-plane and C-plane SLs, the built-in electrostatic field originated from spontaneous and piezoelectric polarization is negligible for A-plane SLs.

In as a Surfactant for the Growth of AlGaN/GaN Heterostructures by Plasma Assisted MBE

2002 ◽  
Vol 743 ◽  
Author(s):  
E. Monroy ◽  
N. Gogneau ◽  
E. Bellet-Amalnc ◽  
F. Enjalbert ◽  
J. Barjon ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Growth Conditions ◽  
Molecular Beam Epitaxy Growth ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dimensional Growth

ABSTRACTIn this paper, we study the surfactant capability of In for the growth of AlGaN/GaN heterostructures by plasma-assisted molecular beam epitaxy. Growth conditions were determined to have a self-regulated 1×1 In adlayer on AlxGa1-xN (0001). The presence of this In film favors two dimensional growth of AlGaN under stoichiometric conditions, and inhibits the formation of metal droplets on the surface. The quality of these layers was assessed by high resolution X-ray diffraction, atomic force microscopy and photoluminescence.

High Epitaxial Growth Rate of 4H-SiC Using Horizontal Hot-Wall CVD

2006 ◽  
Vol 527-529 ◽  
pp. 187-190 ◽  
Author(s):  
Rachael L. Myers-Ward ◽  
Y. Shishkin ◽  
Olof Kordina ◽  
I. Haselbarth ◽  
Stephen E. Saddow
Keyword(s):  
Growth Rate ◽  
Epitaxial Growth ◽  
Growth Process ◽  
Structural Quality ◽  
Growth Time ◽  
Film Morphology ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray

A 4H-SiC epitaxial growth process has been developed in a horizontal hot-wall CVD reactor using a standard chemistry of silane-propane-hydrogen, producing repeatable growth rates up to 32 μm/h. The growth rate was studied as a function of pressure, silane flow rate, and growth time. The structural quality of the films was determined by X-ray diffraction. A 65 μm thick epitaxial layer was grown at the 32 μm/h rate, resulting in a smooth, specular film morphology with occasional carrot-like and triangular defects. The film proved to be of high structural quality with an X-ray rocking curve FWHM value of the (0004) peak of 11 arcseconds.

Superconducting Multilayers: Microstructural Properties Studied by X-Ray Diffraction

1995 ◽  
Vol 382 ◽  
Author(s):  
A. Vailionis ◽  
A. Brazdeikis ◽  
A.S. FlodstrÖm
Keyword(s):  
Molecular Beam ◽  
Interface Roughness ◽  
Structural Quality ◽  
X Ray Diffraction ◽  
Diffraction Profile ◽  
One Dimensional ◽  
X Ray ◽  
Structural Imperfections ◽  
Cell Disorder

ABSTRACTStructural properties of molecular beam epitaxy-grown Bi2Sr2Cu1Oy'Bi2Sr2Ca1Cu2Oy multilayers have been studied by x-ray diffraction. A one-dimensional kinematic x-ray diffraction model has been used to describe the structural quality of the multilayers. Interface roughness, stacking defects and unit cell disorder are obtained by an iterative fitting of the calculated diffraction profile to the experimental spectra. The type and amount of disorder in the films was qualitatively determined. Results demonstrate that structural imperfections are present in the multilayers and have to be considered when transport properties are studied.

Structural Characterization of Bulk AlN Single Crystals Grown from Self-Seeding and Seeding by SiC Substrates

2006 ◽  
Vol 527-529 ◽  
pp. 1521-1524 ◽  
Author(s):  
Balaji Raghothamachar ◽  
Rafael Dalmau ◽  
Michael Dudley ◽  
Raoul Schlesser ◽  
Dejin Zhuang ◽  
...  
Keyword(s):  
Growth Conditions ◽  
Structural Quality ◽  
X Ray Diffraction ◽  
Free Standing ◽  
X Ray ◽  
Highly Strained ◽  
Defect Densities ◽  
High Defect Densities

Using a combination of synchrotron white beam x-ray topography (SWBXT) and high resolution x-ray diffraction (HRXRD), the structural quality of AlN crystals grown by various sublimation-based techniques have been non-destructively analyzed. Spontaneously nucleated AlN crystals are characterized by very low defect densities but their size is small. Self-seeding results in nucleation of multiple grains of different orientations, a few of which are of good quality while most are highly strained. Using readily available commercial 4H and 6H-SiC substrates, several growth runs have been carried out using different growth conditions to obtain thick AlN layers, either attached to the seed or free-standing. While attached layers are typically cracked and highly strained, crack-free free-standing layers can be obtained by delamination or SiC decomposition. X-ray characterization reveals these crystals have good purity but moderately high defect densities.

Ge δ-Layers on Si(111) and Si(001) Grown by MBE and SPE

1994 ◽  
Vol 375 ◽  
Author(s):  
J. Falta ◽  
T. Gog ◽  
G. Materlik ◽  
B. H. Müjller ◽  
M. Horn-Von Hoegen
Keyword(s):  
Room Temperature ◽  
Molecular Beam ◽  
Solid Phase ◽  
Standing Waves ◽  
Solid Phase Epitaxy ◽  
High Crystalline Quality ◽  
X Ray ◽  
High Annealing

AbstractGe δ-layers on Si(111) and Si(001), grown by molecular beam epitaxy (MBE) and solid phase epitaxy (SPE) were characterized in-situ by high-resolution low-energy electrondiffraction and post-growth by x-ray standing waves. LEED intensity oscillations are used to determine the growth mode of Ge on Si which is found to proceed in a double bilayer fashion for Ge on Si(111). X-ray standing waves are employed to investigate crystal quality of the Ge layer. SPE on Si(111) requires high annealing temperatures (600°C) for sufficient recrystallization of defects in the Ge δ-layer. On Si(001), Ge δ-layers of surprisingly high crystalline quality are grown by solid phase epitaxy at room temperature.

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