Quaternary Alloys InxAlyGa1−x-yAs Grown on GaAs with A Compositionally-Step-Graded Buffer

1992 ◽  
Vol 263 ◽  
Author(s):  
C. Fan ◽  
D. W. Shih ◽  
M. W. Hansen ◽  
J. Chen ◽  
P. Z. Lee ◽  
...  
Keyword(s):  
Schottky Barrier ◽  
Lattice Mismatch ◽  
Chemical Reactivity ◽  
Compressive Strain ◽  
X Ray Diffraction ◽  
Quaternary Alloys ◽  
X Ray ◽  
Mismatch Strain ◽  
Barrier Heights ◽  
Gaas Substrates

ABSTRACTFundamental bandgaps and Schottky barrier heights of strain-relaxed quaternary InxAlyGa1−x-yAs alloys with 0 < x < 0.35 and 0 < y < 0.30 were studied. The alloys were grown on GaAs substrates by molecular beam epitaxy. The lattice mismatch (up to 2.5%) and mismatch strain were accommodated by a compositionally-step-graded buffer. A residual compressive strain of less than 0.5% was determined by x-ray diffraction. Measured Schottky barrier heights v.s. bandgap deviate from the values predicted by the “commonanion” rule. This behavior is attributed to the compositional inhomogeneities and chemical reactivity of the air-exposed InAlGaAs surfaces.

Epitaxial tilt of partially relaxed InGaAs layers grown on (100) GaAs substrates

1992 ◽  
Vol 70 (10-11) ◽  
pp. 838-842
Author(s):  
P. Maigné ◽  
A. P. Roth ◽  
C. Desruisseaux ◽  
D. Coulas
Keyword(s):  
Residual Strain ◽  
Gaas Substrate ◽  
Strain Relaxation ◽  
Azimuthal Angle ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Monoclinic Symmetry ◽  
X Ray ◽  
Mismatch Strain ◽  
Gaas Substrates

The structural properties of partially relaxed InxGa1−xAs layers grown on (100) GaAs substrates have been investigated, using high-resolution X-ray diffraction, in order to better understand the mechanisms responsible for the relaxation of the mismatch strain. From symmetric [400] reflections recorded as functions of the azimuthal angle [Formula: see text], the (100) InGaAs planes are found to be tilted with respect to the (100) GaAs substrate planes. The tilt magnitude is first seen to decrease then to increase with layer thickness. The direction of the tilt changes from [01-1] to [00-1] in the range of thickness investigated. From [422] asymmetric reflections, the average in-plane lattice parameter, the indium composition as well as the percentage of relaxation can be measured. Our values for relaxation are in qualitative agreement with the Dodson and Tsao model of strain relaxation (Appl. Phys. Lett. 51, 1710 (1987)). In addition, our data show an anisotropy in residual strain along <011> directions. This anisotropy increases with the amount of strain relieved and changes the crystal symmetry of the cell from tetragonal to monoclinic. This monoclinic symmetry can be characterized by an angle β that measures the angle between 90° and the inner angles of the new crystallographic cell. As for the anisotropy in residual strain, |3 increases with the amount of strain relieved. Correlations between tilt magnitude and tilt direction with the formation of 60° type dislocations are discussed.

Characterizations Of Zr/Si1-x-yGexCy After Rapid Thermal Annealing

1998 ◽  
Vol 533 ◽  
Author(s):  
V. Aubry-Fortuna ◽  
M. Barthula ◽  
F. Meyer ◽  
A. Eyal ◽  
C. Cytermann ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Schottky Barrier ◽  
Rapid Thermal Annealing ◽  
Residual Strain ◽  
Strain Relaxation ◽  
Small Strain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Barrier Heights ◽  
Final Compound

AbstractIn this work, we have investigated the reaction between Zr and SiGeC alloys after Rapid Thermal anneals performed at 800°C for 5 min. The interactions of the metal with the alloy have been investigated by X-Ray diffraction. Four crystal X-Ray diffraction was also performed to measure the residual strain in the epilayer. The final compound of the reaction is the C49- Zr(Si1-xGex)2 phase. The C49 film contains the same Ge concentration as in the as-deposited Si1-x-yGexCy layer. This suggests that no Ge-segregation occurs during annealing. Only a small strain relaxation is detected in the unreacted SiGe epilayer during the reaction. The addition of C in the epilayer prevents any strain relaxation. These results are in contrast with those observed in systems with Ti and Co, and show that the system Zr-Si-Ge is much more stable. Schottky barrier heights have been also measured: annealing leads to a slight decrease of the barrier without any degradation of the contact. The resistivity of the C49 film is about 80 μΩcm. These results indicate that Zr may be a good candidate for contacts on IV-IV alloys in term of thermal stability.

Strain Determination in Epitaxic Films of Materials of Orthorhombic Symmetry by High-Resolution X-ray Diffraction

1998 ◽  
Vol 31 (6) ◽  
pp. 831-834 ◽  
Author(s):  
L. De Caro ◽  
L. Tapfer
Keyword(s):  
High Resolution ◽  
Lattice Mismatch ◽  
Angular Separation ◽  
Orthorhombic Symmetry ◽  
Lattice Deformation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mismatch Strain ◽  
Strain Determination ◽  
Lattice Mismatch Strain

In this paper, we derive the most general expression of the X-ray incidence parameter. The new expression of the incidence parameter allows us to determine the lattice deformation of strained epitaxic films of materials of orthorhombic symmetry by high-resolution X-ray diffraction. The strain status of epilayers can be evaluated by using layer and substrate peaks of different reflections. In particular, the lattice mismatch (strain fields) between substrate and epilayers can be determined even if the heterostructure is made of materials of different crystallographic symmetry,e.g.high-Tcperov-skite superconductor thin films deposited on SrTiO3. In addition, the new expression of the incidence parameter takes into account the most general uniform lattice deformation of the epilayer crystal unit cell. Furthermore, it should be noted that the new expression is particularly useful if the angular separation Δθ between layer and substrate Bragg peaks is so large that the more conventional first- or second-order approximations in Δθ of the incidence parameter are not valid.

W/Si Schottky Diodes: Effect of Metal Deposition Conditions on the Barrier Height

1994 ◽  
Vol 356 ◽  
Author(s):  
M. Mamor ◽  
E. Finkman ◽  
F. Meyer ◽  
K. Bouziane
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Schottky Barrier Height ◽  
Schottky Diodes ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Barrier Heights ◽  
P Type ◽  
Deposition Conditions

AbstractThe Schottky barrier heights (ΦB) for W/Si Schottky diodes have been determined from I–V measurements. The effects of the sputter deposition conditions of the W-films were studied. X-ray diffraction was used to examine the structure and the lattice parameters of the W-films while the stress was determined by using a profilometer from the measurement of the curvature of the substrate after metallization. The resistivity is determined by using a four-point probe. A compressive-to-tensile stress transition is associated with the transformation of the ±—W-phase into the (β—W-phase as the working gas pressure is increased. These effects, which are frequently observed, coïncide with a significant increase of the W-film resistivity and a change (△ΦB≈50 meV) in the Schottky barrier height on n-type. On the other hand, the barrier height on the p-type remains constant under all the experimental conditions investigated. These results are discussed in terms of effects of strain and structure of W-films on the work function of the W, as well as in terms of modification of the pinning position of the Fermi level or else change in the value of the Richardson constant.

scholarly journals Crystalline Growth of Wurtzite GaN on (111) GaAs

1992 ◽  
Vol 242 ◽  
Author(s):  
J. Ross ◽  
M. Rubin ◽  
T. K. Gustafson
Keyword(s):  
Full Width Half Maximum ◽  
Lattice Mismatch ◽  
Rf Magnetron Sputtering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gaas Substrates ◽  
Surface Reconstructions ◽  
Diffraction Patterns ◽  
Reactive Rf Magnetron Sputtering ◽  
Crystalline Growth

ABSTRACTGallium Nitride films were grown on (111) Gallium Arsenide substrates using reactive rf magnetron sputtering. Despite a 20% lattice mismatch and different crystal structure, wurtzite GaN films grew epitaxially in basal orientation on (111) GaAs substrates. Heteroepitaxy was observed for growth temperatures between 550–600°C. X-ray diffraction patterns revealed (0002) GaN peak with a full-width-half-maximum (FWHM) as narrow as 0.17°. Possible surface reconstructions to explain the epitaxial growth are presented.

Time Dependence of γ/γ' Lattice Mismatch in Creep-Deformed Single Crystal Superalloy SC16 at 1173 K

2007 ◽  
Vol 539-543 ◽  
pp. 3059-3063 ◽  
Author(s):  
G. Schumacher ◽  
N. Darowski ◽  
I. Zizak ◽  
Hellmuth Klingelhöffer ◽  
W. Chen ◽  
...  
Keyword(s):  
Single Crystal ◽  
Lattice Mismatch ◽  
Lattice Misfit ◽  
Peak Position ◽  
Single Crystal Superalloy ◽  
Tensile Creep ◽  
Full Width ◽  
X Ray Diffraction ◽  
X Ray ◽  
Time Period

The profiles of 001 and 002 reflections have been measured at 1173 K as a function of time by means of X-ray diffraction (XRD) on tensile-creep deformed specimens of single crystal superalloy SC16. Decrease in line width (full width at half maximum: FWHM) by about 7 % and increase in peak position by about 3x10-4 degrees was detected after 8.5x104 s. Broadening of the 002 peak profile indicated a more negative value of the lattice misfit after the same time period. The results are discussed in the context of the anisotropic arrangement of dislocations at the γ/γ’ interfaces during creep and their rearrangement during the thermal treatment at 1173 K.

Strain Analysis in Thin La1−xCaxMnO3 Films by Grazing Incidence X-ray Scattering

1999 ◽  
Vol 602 ◽  
Author(s):  
M. Petit ◽  
L. J. Martinez-Miranda ◽  
M. Rajeswari ◽  
A. Biswas ◽  
D. J. Kang ◽  
...  
Keyword(s):  
Film Thickness ◽  
Lattice Mismatch ◽  
Compressive Strain ◽  
Strain Analysis ◽  
Grazing Incidence ◽  
Relaxation Processes ◽  
Near Surface ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

AbstractWe have performed depth profile analyses of the lattice parameters in epitaxial thin films of La1−xCaxMno3 (LCMO), where x = 0.33 or 0.3, to understand the evolution of strain relaxation processes in these materials. The analyses were done using Grazing Incidence X-ray Scattering (GIXS) on films of different thicnesses on two different substrates, (100) oriented LaAlO3 (LAO), with a lattice mismatch of ∼2% and (110) oriented NGO, with a lattice mismatch of less than 0.1%. Films grown on LAO can exhibit up to three in-plane strained lattice constants, corresponding to a slight orthorhombic distortion of the crystal, as well as near-surface and columnar lattice relaxation. As a function of film thickness, a crossover from a strained film to a mixture of strained and relaxed regions in the film occurs in the range of 700 Å. The structural evolution at this thickness coincides with a change in the resistivity curve near the metalinsulator transition. The in-plane compressive strain has a range of 0.2 – 1.5%, depending on the film thickness for filsm in the range of 400 - 1500 A.

Optical and structural prorerties of InAs epilayer on graded InGaAs

2001 ◽  
Vol 696 ◽  
Author(s):  
Gu Hyun Kim ◽  
Jung Bum Choi ◽  
Joo In Lee ◽  
Se-Kyung Kang ◽  
Seung Il Ban ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Residual Strain ◽  
Molecular Beam ◽  
Lattice Mismatch ◽  
Peak Position ◽  
Excitation Intensity ◽  
Total Thickness ◽  
Ingaas Layer ◽  
X Ray Diffraction ◽  
X Ray

AbstractWe have studied infrared photoluminescence (PL) and x-ray diffraction (XRD) of 400 nm and 1500 nm thick InAs epilayers on GaAs, and 4 nm thick InAs on graded InGaAs layer with total thickness of 300 nm grown by molecular beam epitaxy. The PL peak positions of 400 nm, 1500 nm and 4 nm InAs epilayer measured at 10 K are blue-shifted from that of InAs bulk by 6.5, 4.5, and 6 meV, respectively, which can be largely explained by the residual strain in the epilayer. The residual strain caused by the lattice mismatch between InAs and GaAs or graded InGaAs/GaAs was observed from XRD measurements. While the PL peak position of 400 nm thick InAs layer is linearly shifted toward higher energy with increase in excitation intensity ranging from 10 to 140 mW, those of 4 nm InAs epilayer on InGaAs and 1500 nm InAs layer on GaAs is gradually blue-shifted and then, saturated above a power of 75 mW. These results suggest that adopting a graded InGaAs layer between InAs and GaAs can efficiently reduce the strain due to lattice mismatch in the structure of InAs/GaAs.

An X-ray scattering study on inverted Ge–Si huts grown at low temperatures

2004 ◽  
Vol 19 (4) ◽  
pp. 347-351
Author(s):  
J. Xu ◽  
X. S. Wu ◽  
B. Qian ◽  
J. F. Feng ◽  
S. S. Jiang ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Lattice Strain ◽  
Lattice Mismatch ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Large Lattice ◽  
Scattering Study

Ge–Si inverted huts, which formed at the Si∕Ge interface of Si∕Ge superlattice grown at low temperatures, have been measured by X-ray diffraction, grazing incidence X-ray specular and off-specular reflectivities, and transmission electron microscopy (TEM). The surface of the Si∕Ge superlattice is smooth, and there are no Ge–Si huts appearing on the surface. The roughness of the surfaces is less than 3 Å. Large lattice strain induced by lattice mismatch between Si and Ge is found to be relaxed because of the intermixing of Ge and Si at the Si∕Ge interface.

Magnetic Anisotropy in Electrodeposited CO Films and spin-valves on Gaas Substrates

1999 ◽  
Vol 562 ◽  
Author(s):  
K. Attenborough ◽  
M. Cerisier ◽  
H. Boeve ◽  
J. De Boeck ◽  
G. Borghs ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Buffer Layer ◽  
Structural Properties ◽  
Easy Axis ◽  
Spin Valve ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cu Films ◽  
Gaas Substrates ◽  
Unique Spin

ABSTRACTWe have studied the magnetic and structural properties of thin electrodeposited Co and Cu layers grown directly onto (100) n-GaAs and have investigated the influence of a buffer layer. A dominant fourfold anisotropy with a uniaxial contribution is observed in 10 nm Co electrodeposited films on GaAs. An easy axis is observed in the [001] GaAs direction with two hard axes of differing coercivities parallel to the [011] and [011] directions. For thicker films the easy axes in the [001] direction becomes less pronounced and the fourfold anisotropy becomes less dominant. Co films of similar thicknesses deposited onto an electrodeposited Cu buffer layer were nearly isotropic. From X-ray diffraction 21 nm Co layers on GaAs were found to be hcp with the c-axis tending to be in the plane of the film. The anisotropy is ascribed to the Co/GaAs interface and is held responsible for the unique spin-valve properties seen recently in electrodeposited Co/Cu films.

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