CaP/Si Heteroepitaxial Layers with Reduced Defect Density

1988 ◽  
Vol 116 ◽  
Author(s):  
A.E. Blakeslee ◽  
M.M. Al—jassim ◽  
J.M. Olson ◽  
K.M. Jones ◽  
S.M. Vernon
Keyword(s):  
Defect Density ◽  
Three Dimensional ◽  
Interface Plane ◽  
Misfit Dislocations ◽  
Cross Sectional ◽  
Single Temperature ◽  
Planar Network ◽  
Reduced Density ◽  
Oxide Contamination ◽  
Threading Defects

AbstractIt is shown that GaP layers grown upon Si at a single temperature of 900ºC can have a crystalline quality superior to that exhibited by previous two—step and one—step growth methods. The layers are characterized by a planar network of misfit dislocations confined to the interface plane an a reduced density of threading dislocations (low 106 cm-2; previously >108). Very few threading defects were observed in areas devoid of amorphous oxide contamination, as shown by HREM examination of cross—sectional samples. A low growth rate during nucleation enhances crystalline perfection, since it decreases the tendency toward three—dimensional islanding.

Transmission Electron Microscopy Study of Epitaxial Co/Au and Co/Pd (111) Multilayers

1992 ◽  
Vol 263 ◽  
Author(s):  
A.E.M. de Veirman ◽  
F. Hakkens ◽  
W. Coene ◽  
F.J.A. Den Broeder
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Interface Plane ◽  
Misfit Dislocations ◽  
Transmission Electron Microscopy Study ◽  
Cross Sectional ◽  
Transmission Electron

ABSTRACTThe results of a transmission electron microscopy study of Co/Au and Co/Pd multilayers are reported. Special emphasis is put on the epitaxial growth and the relaxation of the misfit strain of these high misfit systems. In bright-field cross-sectional images, periodic contrast fringes are observed at the interfaces, which are the result of Moiré interference and which allow determination of the degree of misfit relaxation at the interface. It was established that 80-85% of the misfit is relaxed. From high resolution electron microscopy images the Burgers vector of the misfit dislocations was derived, being a/2<110> lying in the (111) interface plane. The results obtained for the Co/Au and Co/Pd multilayers will be discussed in comparison with those obtained for a bilayer of Co and Au.

Growth of a-plane ZnO Thin Films on r-plane Sapphire by Plasma-assisted MBE

2005 ◽  
Vol 891 ◽  
Author(s):  
Junqing Q. Xie ◽  
J. W. Dong ◽  
A. Osinsky ◽  
P. P. Chow ◽  
Y. W. Heo ◽  
...  
Keyword(s):  
Thin Films ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Zno Thin Films ◽  
Rf Plasma ◽  
Misfit Dislocations ◽  
Epitaxial Relationship ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Small Lattice

ABSTRACTZnO thin films have been epitaxially grown on r-plane sapphire by RF-plasma-assisted molecular beam epitaxy. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies indicate that the epitaxial relationship between ZnO and r-plane sapphire is (1120)ZnO // (1102)sapphire and [0001]ZnO // [1101]sapphire. Atomic force microscopy measurements reveal islands extended along the sapphire [1101] direction. XRD omega rocking curves for the ZnO (1120) reflection measured either parallel or perpendicular to the island direction suggest the defect density anisotropy along these directions. Due to the small lattice mismatch along the ZnO [0001] direction, few misfit dislocations were observed at the ZnO/Al2O3 interface in the high-resolution cross-sectional TEM image with the zone axis along the ZnO [1100] direction.

TEM and SEM Studies of MOCVD-Grown GaP on Si

1985 ◽  
Vol 62 ◽  
Author(s):  
M. M. Ai-Jassim ◽  
J. M. Olson ◽  
K. M. Jones
Keyword(s):  
Defect Density ◽  
Growth Parameters ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Structural Defects ◽  
Organic Chemical ◽  
Cross Sectional ◽  
Plan View ◽  
Si Substrates ◽  
Antiphase Domains

ABSTRACTGaP and GaP/GaAsP epitaxial layers have been grown on Si substrates by metal-organic chemical vapor deposition (MOCVD). These layers were characterized by SEM and TEM plan-view and cross-sectional examination. At growth temperatures ranging from 600° C to 800° C, the initial stages of growth were dominated by three-dimensional nucleation. TEM studies showed that at high temperatures the nuclei were generally misoriented with respect to each other yielding, upon coalescence, polycrystalline layers. The growth of single-crystal layers was achieved by nucleating a 30–50 nm layer of GaP at 500° C, followed by annealing and continued growth at 750 ° C. The defect density in these structures was investigated as a function of various growth parameters and substrate conditions. A high density of structural defects was generated at the Si/GaP interface. The use of 2° off (100) Si substrates resulted in GaP layers free of antiphase domains. These results and their implications are discussed.

The Structure of Spinel/Oxide Reaction Fronts During Spinel-Forming Solid State Reactions

1994 ◽  
Vol 357 ◽  
Author(s):  
D. Hesse ◽  
R. Scholz ◽  
S. Senz ◽  
H. Sieber ◽  
P. Werner ◽  
...  
Keyword(s):  
Solid State ◽  
Reaction Front ◽  
Lattice Misfit ◽  
Solid State Reactions ◽  
Interface Plane ◽  
Misfit Dislocations ◽  
Spinel Oxide ◽  
Oxygen Sublattice ◽  
Cross Sectional ◽  
Reaction Fronts

AbstractA series of spinels were grown by topotaxial solid state reaction on MgO(001) and sapphire(11.2) substrates. The structure of the various spinel/oxide reaction fronts was investigated by cross-sectional high resolution electron microscopy and other methods. While for extremely low misfit the reaction front is completely coherent, different interfacial defects form in other cases, depending on sign and amount of the spinel/oxide lattice misfit. For a large positive misfit, a network of misfit dislocations occured all running along <100<, with Burgers vectors of types a/2[101] and a/2[011] pointing out of the interface. The perpendicular Burgers vector component along [001] permits these dislocations to glide in order to cope with the advancing reaction front, avoiding kinetically unfavourable climb processes. The latter have, however, been observed in negative misfit, where the interfacial dislocations run along <110>, with their Burgers vectors lying in the interface plane. At the sapphire/MgAl2O4 front the structure is completely different. Here the h.c.p.-type oxygen sublattice of sapphire is reconstructed into the f.c.c-type oxygen sublattice of the spinel, which requires a tilt of the MgAl2O4 lattice and the formation of interfacial ledges.

Solid Phase Epitaxial Regrowth of Implantation Amorphized Si0.7Ge0.3 Grown on (100) Silicon

1991 ◽  
Vol 235 ◽  
Author(s):  
C. Lee ◽  
K. S. Jones
Keyword(s):  
Defect Density ◽  
Solid Phase ◽  
Three Dimensional ◽  
Stacking Faults ◽  
Solid Phase Epitaxy ◽  
Cross Sectional ◽  
Strained Layers ◽  
Epitaxial Regrowth ◽  
Transmission Electron ◽  
Interfacial Strain

ABSTRACTThe solid phase epitaxial regrowth (SPER) process of implantation amorphized Si0.7Ge0.3 layers (850± Å thick) grown on (100) Si has been studied by cross-sectional transmission electron microscopy. For amorphous layers produced by 40 Ar+ implantation highly defective three dimensional regrowth was observed in both Si0.7Ge0.3 and Si. Stacking faults were the principle defect formed of both materials during regrowth. SPER after amorphization via 73 Ge+ implantation was also investigated. It was found that the SPER velocity of the 73 Ge+ implanted Si0.7 Ge0.7 Ge0.3 was about twice the velocity of the 40 Ar+ implanted samples; for 73 Ge+ implanted Si it was about three times that of the 40Ar+ implanted samples. The activation energy for SPER in 40Ar+ and in 73 Ge+ implanted Si0.7 Geo0.3 was about 1.6 and 2.6 eV, respectively. The defect density was significantly reduced in 73 Ge+ amorphized Si but not in the 73 Ge+ amorphized Si0.7 Ge0.3. It is proposed that limited Ar solubility inhibits high quality regrowth in both SiGe and Si. Upon 73 Ge+ amorphization and solid phase epitaxy the interfacial strain between the SiGe and Si cannot be accommodated. Thus the epitaxial process is poor in these SiGe strained layers regardless of the amorphizing species.

scholarly journals Accuracy and Reproducibility of Facial Measurements of Digital Photographs and Wrapped Cone Beam Computed Tomography (CBCT) Photographs

Diagnostics ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 757
Author(s):  
Maged Sultan Alhammadi ◽  
Abeer Abdulkareem Al-mashraqi ◽  
Rayid Hussain Alnami ◽  
Nawaf Mohammad Ashqar ◽  
Omar Hassan Alamir ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Soft Tissue ◽  
Cone Beam Computed Tomography ◽  
High Reliability ◽  
Three Dimensional ◽  
Cone Beam ◽  
Cross Sectional ◽  
Facial Profile ◽  
Digital Photographs ◽  
Gonial Angle

The study sought to assess whether the soft tissue facial profile measurements of direct Cone Beam Computed Tomography (CBCT) and wrapped CBCT images of non-standardized facial photographs are accurate compared to the standardized digital photographs. In this cross-sectional study, 60 patients with an age range of 18–30 years, who were indicated for CBCT, were enrolled. Two facial photographs were taken per patient: standardized and random (non-standardized). The non-standardized ones were wrapped with the CBCT images. The most used soft tissue facial profile landmarks/parameters (linear and angular) were measured on direct soft tissue three-dimensional (3D) images and on the photographs wrapped over the 3D-CBCT images, and then compared to the standardized photographs. The reliability analysis was performed using concordance correlation coefficients (CCC) and depicted graphically using Bland–Altman plots. Most of the linear and angular measurements showed high reliability (0.91 to 0.998). Nevertheless, four soft tissue measurements were unreliable; namely, posterior gonial angle (0.085 and 0.11 for wrapped and direct CBCT soft tissue, respectively), mandibular plane angle (0.006 and 0.0016 for wrapped and direct CBCT soft tissue, respectively), posterior facial height (0.63 and 0.62 for wrapped and direct CBCT soft tissue, respectively) and total soft tissue facial convexity (0.52 for both wrapped and direct CBCT soft tissue, respectively). The soft tissue facial profile measurements from either the direct 3D-CBCT images or the wrapped CBCT images of non-standardized frontal photographs were accurate, and can be used to analyze most of the soft tissue facial profile measurements.

scholarly journals A Numerical Study of Sub-Millisecond Integrated Mix-and-Inject Microfluidic Devices for Sample Delivery at Synchrotron and XFELs

2021 ◽  
Vol 11 (8) ◽  
pp. 3404
Author(s):  
Majid Hejazian ◽  
Eugeniu Balaur ◽  
Brian Abbey
Keyword(s):  
Molecular Dynamics ◽  
Flow Rate ◽  
Numerical Study ◽  
Three Dimensional ◽  
Microfluidic Devices ◽  
Liquid Jets ◽  
Mixing Efficiency ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Time Required

Microfluidic devices which integrate both rapid mixing and liquid jetting for sample delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for sample delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.

scholarly journals The patellofemoral morphology and the normal predicted value of tibial tuberosity-trochlear groove distance in the Chinese population

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhe Li ◽  
Guanzhi Liu ◽  
Run Tian ◽  
Ning Kong ◽  
Yue Li ◽  
...  
Keyword(s):  
Individual Differences ◽  
Chinese Population ◽  
Pearson Correlation ◽  
Three Dimensional ◽  
Correlation Coefficients ◽  
Tibial Tuberosity ◽  
Trochlear Groove ◽  
Lasso Regression ◽  
Cross Sectional ◽  
Anterior Posterior

Abstract Background Our objective was to obtain normal patellofemoral measurements to analyse sex and individual differences. In addition, the absolute values and indices of tibial tuberosity-trochlear groove (TT-TG) distances are still controversial in clinical application. A better method to enable precise prediction is still needed. Methods Seventy-eight knees of 78 participants without knee pathologies were included in this cross-sectional study. A CT scan was conducted for all participants and three-dimensional knee models were constructed using Mimics and SolidWorks software. We measured and analysed 19 parameters including the TT-TG distance and dimensions and shapes of the patella, femur, tibia, and trochlea. LASSO regression was used to predict the normal TT-TG distances. Results The dimensional parameters, TT-TG distance, and femoral aspect ratio of the men were significantly larger than those of women (all p values < 0.05). However, after controlling for the bias from age, height, and weight, there were no significant differences in TT-TG distances and anterior-posterior dimensions between the sexes (all p values > 0.05). The Pearson correlation coefficients between the anterior femoral offset and other indexes were consistently below 0.3, indicating no relationship or a weak relationship. Similar results were observed for the sulcus angle and the Wiberg index. Using LASSO regression, we obtained four parameters to predict the TT-TG distance (R2 = 0.5612, p < 0.01) to achieve the optimal accuracy and convenience. Conclusions Normative data of patellofemoral morphology were provided for the Chinese population. The anterior-posterior dimensions of the women were thicker than those of men for the same medial-lateral dimensions. More attention should be paid to not only sex differences but also individual differences, especially the anterior condyle and trochlea. In addition, this study provided a new method to predict TT-TG distances accurately.

scholarly journals 3D-Volume Rendering of the Pelvis with Emphasis on Paraurethral Structures Based on MRI Scans and Comparisons between 3D Slicer and OsiriX®

2021 ◽  
Vol 45 (3) ◽  
Author(s):  
C. M. Durnea ◽  
S. Siddiqi ◽  
D. Nazarian ◽  
G. Munneke ◽  
P. M. Sedgwick ◽  
...  
Keyword(s):  
Image Processing ◽  
Secondary Analysis ◽  
Three Dimensional ◽  
3D Models ◽  
Clinical Role ◽  
Cross Sectional ◽  
3D Slicer ◽  
Mri Scans ◽  
3D Volume ◽  
Good Agreement

AbstractThe feasibility of rendering three dimensional (3D) pelvic models of vaginal, urethral and paraurethral lesions from 2D MRI has been demonstrated previously. To quantitatively compare 3D models using two different image processing applications: 3D Slicer and OsiriX. Secondary analysis and processing of five MRI scan based image sets from female patients aged 29–43 years old with vaginal or paraurethral lesions. Cross sectional image sets were used to create 3D models of the pelvic structures with 3D Slicer and OsiriX image processing applications. The linear dimensions of the models created using the two different methods were compared using Bland-Altman plots. The comparisons demonstrated good agreement between measurements from the two applications. The two data sets obtained from different image processing methods demonstrated good agreement. Both 3D Slicer and OsiriX can be used interchangeably and produce almost similar results. The clinical role of this investigation modality remains to be further evaluated.

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