Pressure Ratio (PAs/PGa) Dependence on Low Temperature GaAs Buffer Layers Grown by MBE

1993 ◽  
Vol 325 ◽  
Author(s):  
M. Lagadas ◽  
Z. Hatzopoulos ◽  
M. Calamiotou ◽  
M. Kayiambaki ◽  
A. Christou
Keyword(s):  
Electrical Properties ◽  
Lattice Mismatch ◽  
Pressure Ratio ◽  
Electron Trap ◽  
Buffer Layers ◽  
High Crystalline Quality ◽  
Double Crystal ◽  
X Ray ◽  
Structural And Electrical Properties ◽  
Low Temperature Gaas

AbstractWe have investigated the influence of the pressure ratio (PAs4/PGa) on the structural and electrical properties of GaAs layers grown at 250°C by MBE. SEM photographs have revealed smooth surfaces for PAs4/PGa≥15 and Double crystal X-ray rocking curves have shown an increase on the lattice mismatch δaI/a of the L.T. grown layers and high crystalline quality. Resistivity has not been affected by the different values of PAs4/PGa. n-GaAs epilayers grown on top of L.T. buffer layers have their mobility decreased and the electron trap density increased as revealed by Hall and DLTS measurements.

Structural and Electrical Properties of Colossal Magnetoresistive LSMO Thin Films Prepared by KrF Laser Ablation Method

2001 ◽  
Vol 666 ◽  
Author(s):  
Fumiaki Mitsugi ◽  
Tomoaki Ikegami ◽  
Kenji Ebihara ◽  
Jagdish Narayan ◽  
Alexander M. Grishin
Keyword(s):  
Thin Films ◽  
Laser Ablation ◽  
Electrical Properties ◽  
Lattice Mismatch ◽  
X Ray Diffraction ◽  
Axis Orientation ◽  
X Ray ◽  
Colossal Magnetoresistive ◽  
Laser Ablation Method ◽  
Structural And Electrical Properties

ABSTRACTWe prepared colossal magnetoresistive La0.8Sr0.2MnO3 thin films on the MgO, SrTiO3 and LaAlO3 single crystal substrates using KrF excimer pulsed laser ablation technique. The structural and electrical properties of the La0.8Sr0.2MnO3 thin films which were strained by the lattice mismatch are reported. The in-plane lattice mismatch between the La0.8Sr0.2MnO3 and MgO, SrTiO3 and LaAlO3 substrates are -7.8 %, -0.5 % and +2.3 %, respectively. The X-ray diffraction spectra of the films exhibited c-axis orientation. In the case of the La0.8Sr0.2MnO3 / LaAlO3 thin films with thickness over 100 nm, the divided (00l) peaks were observed. The surface morphology and transport property of the strongly stressed La0.8Sr0.2MnO3 / LaAlO3 were different from those of La0.8Sr0.2MnO3 / MgO and La0.8Sr0.2MnO3 / SrTiO3thin films.

Precipitation of as in low-temperature MBE-grown gaas

1992 ◽  
Vol 50 (2) ◽  
pp. 1376-1377
Author(s):  
M. E. Twigg ◽  
M. Fatemi ◽  
B. Tadayon
Keyword(s):  
Low Temperature ◽  
Field Effect Transistors ◽  
Lattice Parameter ◽  
Buffer Layers ◽  
Double Crystal ◽  
Rocking Curve ◽  
Materials Properties ◽  
X Ray ◽  
Low Temperature Gaas ◽  
High Range

Recent work, on As rich GaAs buffer layers grown at low temperatures by molecular beam epitaxy (MBE), shows that this material has electronic and materials properties that differ from GaAs grown at higher temperatures. Among the interesting properties of these buffer layers are reduced recombination times and high breakdown voltages useful in power field effect transistors (FETs). We have used TEM, in conjunction with double crystal x-ray rocking curves, in studying GaAs grown and annealed at a variety of temperatures. X-ray rocking curve analysis has separated LT (low temperature) GaAs growth into three ranges of growth temperature: the “low-range” below 215°C, the “mid-range” from 215 to 340°C, and the “high-range” above 340°C. The low-range material is amorphous, as suggested by the presence of only the bulk reflections in the x-ray diffractometei profile and from HRTEM images of the MBE-grown buffer layer. The mid-range is single crystal and defect-free, although larger in lattice parameter than stoichiometric GaAs by as much as 0.08%.

Structural and Electrical Properties of Heteroepitaxial HgCdTe/CdZnTe/GaAs/Si

1989 ◽  
Vol 161 ◽  
Author(s):  
S.M. Johnson ◽  
W.L. Ahlgren ◽  
M. H. Kalisher ◽  
J. B. James ◽  
W. J. Hamilton
Keyword(s):  
Electrical Properties ◽  
Hall Effect ◽  
Lattice Mismatch ◽  
Biaxial Tension ◽  
Gaas Layer ◽  
X Ray ◽  
Si Substrates ◽  
Structural And Electrical Properties ◽  
Before And After ◽  
Hall Effect Measurements

ABSTRACTThe structural and electrical properties of heteroepitaxial HgCdTe/CdZnTe/GaAs/Si were evaluated using high-resolution x-ray diffraction techniques and Hall-effect measurements as a function of temperature. Significant tilting of the layers was found for both {100} and {111} CdZnTe layers grown on misoriented {100}GaAs/Si substrates, consistent with the interpretation of a low-angle tilt boundary being formed at the interface to relieve the large lattice mismatch between the layers. The GaAs layer is in a state of biaxial tension before and after the growth of the CdZnTe layers. The x-ray FWHM of HgCdTe layers grown by LPE on these substrates was found to be reduced from that of the MOCVD-grown CdZnTe buffer layer due to both an annealing effect during LPE growth and to the increased distance of layer surface from the defective CdZnTe/GaAs interface. Hall-effect mobility for {100}HgCdTe layers was nearly identical to that of layers grown on bulk CdZnTe substrates. High-quality heterojunction infrared detectors have been fabricated using these materials.

Fabrication and study the effect of the laser on the properties of the compound Tl2-xHgxBa2-ySryCa2Cu3O10+δ superconductor

2018 ◽  
pp. 168
Author(s):  
A. Kareem Dahash Ali ◽  
Nihad Ali Shafeek
Keyword(s):  
Transition Temperature ◽  
Solid State ◽  
Hydrostatic Pressure ◽  
Electrical Properties ◽  
Co2 Laser ◽  
Temperature Shift ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural And Electrical Properties

This study included the fabrication of    compound (Tl2-xHgxBa2-ySryCa2Cu3O10+δ) in a manner solid state and under hydrostatic pressure ( 8 ton/cm2) and temperature annealing(850°C), and determine the effect of the laser on the structural and electrical properties elements in the compound, and various concentrations of x where (x= 0.1,0.2,0.3 ). Observed by testing the XRD The best ratio of compensation for x is 0.2 as the value of a = b = 5.3899 (A °), c = 36.21 (A °) show that the installation of four-wheel-based type and that the best temperature shift is TC= 142 K  .When you shine a CO2 laser on the models in order to recognize the effect of the laser on these models showed the study of X-ray diffraction of these samples when preparing models with different concentrations of the values ​​of x, the best ratio of compensation is 0.2 which showed an increase in the values ​​of the dimensions of the unit cell a=b = 5.3929 (A °), c = 36.238 (A°). And the best transition temperature after shedding laser is TC=144 K. 

Thermal Strain Study of Almost Lattice-Matched Epitaxial InuGa1-uAs1-vP1-v Films on InP(100) Substrates

1989 ◽  
Vol 160 ◽  
Author(s):  
G. Bai ◽  
M-A. Nicolet ◽  
S.-J. Kim ◽  
R.G. Sobers ◽  
J.W. Lee ◽  
...  
Keyword(s):  
Room Temperature ◽  
Epitaxial Film ◽  
Lattice Mismatch ◽  
Thermal Strain ◽  
Growth Direction ◽  
Epitaxial Films ◽  
Double Crystal ◽  
X Ray ◽  
Lattice Matched ◽  
Coherent Interfaces

AbstractSingle layers of ~ 0.5µm thick InuGa1-uAs1-vPv (0.52 < u < 0.63 and 0.03 < v < 0.16) were grown epitaxially on InP(100) substrates by liquid phase epitaxy at ~ 630°C. The compositions of the films were chosen to yield a constant banndgap of ~ 0.8 eV (λ = 1.55 µm) at room temperature. The lattice mismatch at room temperature between the epitaxial film and the substrate varies from - 4 × 10-3 to + 4 × 10-3. The strain in the films was characterized in air by x-ray double crystal diffractometry with a controllable heating stage from 23°C to ~ 700°C. All the samples have an almost coherent interfaces from 23°C to about ~ 330°C with the lattice mismatch accomodated mainly by the tetragonal distortion of the epitaxial films. In this temperature range, the x-ray strain in the growth direction increases linearly with temperature at a rate of (2.0 ± 0.4) × 10-6/°C and the strain state of the films is reversible. Once the samples are heated above ~ 300°C, a significant irreversible deterioration of the epitaxial films sets in.

Structural and electrical properties of Cu-doped Ni–Zn nanocrystalline ferrites for MLCI applications

2017 ◽  
Vol 31 (33) ◽  
pp. 1750318 ◽  
Author(s):  
D. Venkatesh ◽  
K. V. Ramesh
Keyword(s):  
Electrical Properties ◽  
Cation Distribution ◽  
Tetrahedral Site ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Structural And Electrical Properties ◽  
Phase Spinel ◽  
Diffraction Patterns

Polycrystalline Cu substituted Ni–Zn ferrites with chemical composition Ni[Formula: see text]Zn[Formula: see text]-Cu[Formula: see text]Fe2O4 (x = 0.00 to 0.25 in steps of 0.05) have been prepared by citrate gel autocombustion method. The samples for electrical properties have been sintered at 900[Formula: see text]C for 4 h. The X-ray diffraction patterns of all samples indicate the formation of single phase spinel cubic structure. The value of lattice parameter is decreases with increasing Cu concentration. The estimated cation distribution can be derived from X-ray diffraction intensity calculations and IR spectra. The tetrahedral and octahedral bond lengths, bond angles, cation–cation and cation–anion distances were calculated by using experimental lattice parameter and oxygen positional parameters. It is observed that Cu ions are distributed in octahedral site and subsequently Ni and Fe ions in tetrahedral site. The grain size of all samples has been calculated by Scanning Electron Microscopy (SEM) images. The variations in DC electrical resistivity and dielectric constant have been explained on the basis of proposed cation distribution.

Non-Stoichiometry and Structure of SrCe1-xYbxO3 Perovskite-Type Oxides

1996 ◽  
Vol 453 ◽  
Author(s):  
Igor Kosacki ◽  
Mark Shumsky ◽  
Harlan U. Anderson
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Charge Carrier ◽  
Structural Properties ◽  
Electrical Transport ◽  
Structural Disorder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural And Electrical Properties ◽  
Perovskite Type

AbstractThe structural and electrical properties of SrCe1-xYbxO3 ceramics have been studied as a function of temperature and Yb-concentration using x-ray diffraction and impedance techniques. The influence of Yb-dopants on electrical transport and structural disorder has been studied. A correlation between the structural properties, electrical conductivity is observed and discussed. These measurements allow us to determine the mechanism of charge carrier compensation and also the concentration and mobility of the electrical species.

Effect of La doping on the structural and electrical properties of SrBi2Ta2O9

2004 ◽  
Vol 811 ◽  
Author(s):  
Ortega Nora ◽  
S. Bhattacharyya ◽  
P. Bhattacharya ◽  
R.R. Das ◽  
R.S. Katiyar
Keyword(s):  
Electrical Properties ◽  
Structural Evolution ◽  
Phase Segregation ◽  
X Ray Diffraction ◽  
Lanthanum Doping ◽  
X Ray ◽  
La Doping ◽  
Structural And Electrical Properties ◽  
Vibrational Characteristics ◽  
La Substitution

ABSTRACTThe effect of anthanum substitution (0-20%) on phase formation, structural evolution and electrical properties of SrBi2Ta2O9 (SBT) ceramics were investigated. X-ray diffraction studies revealed that phase pure SBT bulk samples can be synthesized with lanthanum doping without any phase segregation. Raman spectroscopy was used to understand the lattice vibrational characteristics of La substituted SBT compound. The ferroelectric soft mode at 27 cm−1 was shifted towards the lower frequencies at room temperature with increase in La concentrations. The octahedral stretching mode (O-Ta-O) did not influenced by La substitution in SBT. The x-ray photoemission spectroscopy measurements showed the decrease of binding energy of Bi 4f core levels (5/2 and 7/2) upon La substitution in SBT. The dielectric constant was increased from 120 to 190 up to 10% La doping and decreased with further increase in La concentration.

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