Effect of the Ge preamorphisation dose on the thermal evolution of End of Range defects

2001 ◽  
Vol 669 ◽  
Author(s):  
B. Colombeau ◽  
F. Cristiano ◽  
J-C. Marrot ◽  
G. Ben Assayag ◽  
A. Claverie
Keyword(s):  
Ostwald Ripening ◽  
Defect Density ◽  
Thermal Evolution ◽  
Plan View ◽  
Transmission Electron ◽  
The Matrix ◽  
Mean Size ◽  
Defect Size Distribution ◽  
Increasing Function ◽  
Imaging Conditions

ABSTRACTIn this paper, we study the effect of the Ge+ preamorphisation dose on the thermal evolution of End of Range (EOR) defects upon annealing. Amorphisations were carried out by implanting Ge+ at 150 keV to doses ranging from 1×1015 ions/cm2 to 8×1015ions/cm2. Rapid Thermal Annealing (RTA) was performed for various time/temperature combinations in nitrogen ambient. Plan view transmission electron microscopy under specific imaging conditions was used to measure the size distributions and densities of the EOR defects. We found that for a fixed thermal budget, the increase in the Ge ion dose results in an increase in the defect density but has no effect on the defect size distribution. This invariance of the mean size of defects with respect to the initial supersaturation introduced in the matrix is an expected characteristic of a conservative Ostwald ripening mechanism. Moreover, the total number (Nb) of Si interstitial atoms bound to the EOR defects is a monotonically increasing function of the Ge ion dose. Furthermore, we found that Nb is directly proportional to the number of Si atoms in excess of the vacancies found below the a/c interface as calculated by MonteCarlo simulations. This is consistent with the “excess interstitial” model which explains the origin of the EOR defects.

Defect Evolution During Laser Annealing

2006 ◽  
Vol 912 ◽  
Author(s):  
Susan B. Felch ◽  
Abhilash Mayur ◽  
Vijay Parihar ◽  
Faran Nouri ◽  
Kevin S. Jones ◽  
...  
Keyword(s):  
Laser Annealing ◽  
Annealing Temperature ◽  
Defect Density ◽  
Operating Conditions ◽  
Maximum Temperature ◽  
Plan View ◽  
Residual Defect ◽  
Low Temperature Annealing ◽  
Transmission Electron ◽  
Boron Dopant

AbstractImplementation of millisecond annealing requires the identification of the operating conditions for that technique which minimize the residual defects. In addition, possible combinations of low temperature annealing with millisecond annealing could result in minimal residual defects. The samples studied here were implanted with Ge+ pre-amorphization and boron dopant ions and were activated with a scanning laser annealing technique with maximum temperature dwell times of about one millisecond. The laser anneal conditions were varied, along with combinations of spike anneals. The annealed samples were analyzed by plan-view transmission electron microscopy (TEM) to measure the residual defect density and size. The effects of spike temperature, laser annealing temperature, and scan rate will be discussed.

LOW-Temperature Epitaxial Growth of GaAs on Si Substrates by MBE

1992 ◽  
Vol 263 ◽  
Author(s):  
Ting-Yen Chiang ◽  
En-Huery Liu ◽  
Der-Hwa Yiin ◽  
Tri-Rung Yew
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Epitaxial Growth ◽  
Defect Density ◽  
Solution Treatment ◽  
Plan View ◽  
Si Substrates ◽  
Gaas On Si ◽  
Transmission Electron

ABSTRACTThis paper presents results of the low—temperature epitaxial growth of GaAs on Si substrates with orientation 1°—4° off (100) by molecular beam epitaxy (MBE). The epitaxial growth ·is carried out on Si wafers subjected to HF solution treatment by “spin-etch” technique before the wafer is transferred to the entry chamber of MBE system. Methods used for reducing defect density in the epitaxial layers are proposed. The characterization techniques include cross-sectional transmission electron microscopy (XTEM), plan-view transmission electron microscopy, scanning electron microscopy (S EM), and double crystal X-ray diffraction (DCXRD). Epitaxial films with a full width at half—maximum (FWHM) of about 310 arcsec measured by DCXRD are obtained without annealing.-

Structural modifications in H-implanted and laser desorbed Si

1992 ◽  
Vol 50 (1) ◽  
pp. 48-49
Author(s):  
P. Zheng ◽  
R.G. Saint-Jacques ◽  
R. Boivin ◽  
B. Terreault
Keyword(s):  
Dynamic Imaging ◽  
Elastic Recoil ◽  
Cross Sectional ◽  
Plan View ◽  
Near Surface ◽  
Elastic Recoil Detection ◽  
Structural Modifications ◽  
Transmission Electron ◽  
Imaging Conditions ◽  
Hydrogen Ion Implantation

Near-surface microstructural modifications of silicon which occur in hydrogen ion implantation and classical thermal desorption have already been reported. Our work is related to desorption using an intense and pulsed laser. The particularity of this technique is only the surface (≈2μm) heated. We report results of transmission electron microscopy (TEM) of the microstructural modifications in H-implanted and laser desorbed silicon.Silicon [001] oriented has been implanted with 5 keV H to a dose of 1017cm-2 and desorbed with a ruby laser (694.3 nm, 30 ns). It received an energy of 0.9 J.cm-2 and its surface temperature reached the melting point. This sample was totally desorbed as indicated by mass spectroscopy and checked by Elastic Recoil Detection. Plan-view [001] and cross-sectional [110] TEM samples were mechano-chemically thinned (10% HF + 90% HNO3). TEM dynamic imaging conditions (imaging vector g=220, w=0) were used to observe the defects.

1.6 μm Emission from InAs Quantum Dots grown on a GaAs Substrate using an AlGaAsSb Metamorphic Buffer

2002 ◽  
Vol 737 ◽  
Author(s):  
G. Balakrishnan ◽  
S. Birudavolu ◽  
L. R. Dawson ◽  
D. L. Huffaker ◽  
Huifang Xu ◽  
...  
Keyword(s):  
Gaas Substrate ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Matrix Material ◽  
Metamorphic Buffer ◽  
Transmission Electron ◽  
Digital Alloy ◽  
The Matrix ◽  
Matrix Lattice ◽  
Wavelength Emission

ABSTRACTWe report 1.6 μm emission from InAs QDs (QDs) grown on a GaAs substrate. The ensemble is grown on a graded digital alloy (DA), which increases the matrix lattice constant from 5.65 Å to 5.77 Å. The reduced lattice mismatch between the InAs and matrix material produces larger QDs and thereby allows longer wavelength emission compared to standard growth techniques. The resulting QD density ranges from 2×1010 to 8×1010/cm2 with QD dimensions of 5nm x 30nm measured using atomic force microscopy (AFM). According to x-ray diffraction (XRD) data and transmission electron microscopy (TEM), the metamorphic buffer is unstrained with low defect density.

Thermally induced hillock formation in Al–Cu films

1989 ◽  
Vol 4 (5) ◽  
pp. 1172-1181 ◽  
Author(s):  
C. Y. Chang ◽  
R. W. Vook
Keyword(s):  
Isothermal Annealing ◽  
Ostwald Ripening ◽  
Spectroscopy Analysis ◽  
Thermally Induced ◽  
Cu Films ◽  
Transmission Electron ◽  
The Matrix ◽  
Order Of Magnitude ◽  
Average Size

Isothermal annealing studies of hillocks formed on Al–15 wt.% Cu films, vapor deposited at 25 °C on oxidized silicon wafers, were carried out in situ in a scanning electron microscope. The original hillocks formed as a result of substrate-induced thermal expansion strains which caused material to diffuse out of the film to form the hillocks when the films were heated to the isothermal annealing temperatures. During isothermal annealing the hillock density decreased and the average size of the hillocks increased. Measurements of these quantities as a function of time were made at a series of temperatures ranging from 200 to 300 °C. The activation energies for these two cases were found to be 0.29 and 0.28 eV, respectively. X-ray energy spectroscopy analysis of the films showed that the hillocks were richer in copper than the matrix. Transmission electron microscopy showed that the average hillock and grain sizes in the variously annealed films were linearly related and of the same order of magnitude. The results were also analyzed using Chakraverty's models for surface and interfacial diffusion. It was concluded that the evidence clearly shows that the observed processes could be well characterized by a typical Ostwald ripening model.

scholarly journals Screw Dislocations in GaN Grown by Different Methods

2004 ◽  
Vol 10 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Z. Liliental-Weber ◽  
D. Zakharov ◽  
J. Jasinski ◽  
M.A. O'Keefe ◽  
H. Morkoc
Keyword(s):  
Dislocation Core ◽  
Hydride Vapor Phase Epitaxy ◽  
Scattered Electron ◽  
Atomic Column ◽  
Plan View ◽  
Screw Dislocations ◽  
The Core ◽  
Transmission Electron ◽  
The Matrix ◽  
High Resolution Images

A study of screw dislocations in hydride-vapor-phase-epitaxy (HVPE) template and molecular-beam-epitaxy (MBE) overlayers was performed using transmission electron microscopy (TEM) in plan view and in cross section. It was observed that screw dislocations in the HVPE layers were decorated by small voids arranged along the screw axis. However, no voids were observed along screw dislocations in MBE overlayers. This was true both for MBE samples grown under Ga-lean and Ga-rich conditions. Dislocation core structures have been studied in these samples in the plan-view configuration. These experiments were supported by image simulation using the most recent models. A direct reconstruction of the phase and amplitude of the scattered electron wave from a focal series of high-resolution images was applied. It was shown that the core structures of screw dislocations in the studied materials were filled. The filed dislocation cores in an MBE samples were stoichiometric. However, in HVPE materials, single atomic columns show substantial differences in intensities and might indicate the possibility of higher Ga concentration in the core than in the matrix. A much lower intensity of the atomic column at the tip of the void was observed. This might suggest presence of lighter elements, such as oxygen, responsible for their formation.

Screw Dislocations in MBE GaN Layers Grown on Top of HVPE Layers: Are They Different?

2002 ◽  
Vol 743 ◽  
Author(s):  
Z. Liliental-Weber ◽  
D. Zakharov ◽  
J. Jasinski ◽  
J. Washburn ◽  
M. A. O'Keefe ◽  
...  
Keyword(s):  
Cross Section ◽  
Electron Wave ◽  
Scattered Electron ◽  
Screw Axis ◽  
Plan View ◽  
Screw Dislocations ◽  
The Core ◽  
Transmission Electron ◽  
The Matrix ◽  
High Resolution Images

ABSTRACTTransmission Electron Microscopy was applied to study HVPE template and MBE over-layers in plan-view and cross-section. It was observed that screw dislocations in the HVPE layers are decorated by small voids arranged along the screw axis. However, no voids were observed along screw dislocations in MBE overlayers grown with excess Ga, despite the fact that Ga droplets were observed on the layer surface as well as imbedded in the layer. By applying a direct reconstruction of the phase and amplitude of the scattered electron wave from a focal series of high-resolution images, the core structures of screw dislocations in both materials have been studied and show that all screw dislocations have filled cores. Dislocation cores in MBE samples grown Ga-rich and N-rich show no substantial differences and no stoichiometric change compared to the matrix. However, in HVPE materials, single atomic columns show substantial differences in intensities and indicate the possibility of Ga presence. These Ga-rich cores might be responsible for the attraction impurities forming voids in their close vicinity.

Effect of Substrate Misorientation on the Structual Strain and Defect Distribution of Mocvd Grown GaAs on Si

1988 ◽  
Vol 116 ◽  
Author(s):  
K.C. Hsieh ◽  
M.S. Feng ◽  
G.E. Stillman ◽  
C.R. Ito ◽  
D.G. McIntyre ◽  
...  
Keyword(s):  
Defect Density ◽  
Chemical Vapor ◽  
Asymmetric Distribution ◽  
Furnace Annealing ◽  
Double Crystal ◽  
Strain Anisotropy ◽  
Plan View ◽  
Defect Distribution ◽  
Si Substrates ◽  
Transmission Electron

Astract:A systematic study of the structural properties and defect distribution of GaAs layers grown by metalorganic chemical vapor deposition on Si substrates misoriented 1°, 1.5°, 2°, 4°, and 6° from [100] toward [011] is reported. Double crystal x-ray rocking curves, cross-section and plan-view Transmission Electron Microscopy (TEM) are used to characterize the structural strain and defect distribution of as-grown and annealed GaAs layers. Both strain and defect density in the GaAs layers are found to be dependent of the degree of substrate misorientation as well as the direction in which measurements are made. Plan-view TEM shows an asymmetric distribution of microtwins in two perpendicular directions. There exists a correlation between the directionality of the strain and of the defect density. Furnace annealing at 850°C for 30 minutes in an arsine overpressure can reduce significantly the defects, the strain and the strain anisotropy. It is found that microtwins are of the highest density when the substrate is misoriented about 4 degrees for the as-grown samples. Though a reduction of defects after annealing occurs for all samples, the least misoriented one shows the most improvement.

Defect investigation of GaN thin films etched by photo-electrochemical and hot wet etching by atomic force and transmission electron microscopy

2001 ◽  
Vol 680 ◽  
Author(s):  
P. Visconti ◽  
K. M. Jones ◽  
M. A. Reshchikov ◽  
R. Cingolani ◽  
H. Morkoç ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Defect Density ◽  
Wet Etching ◽  
Hydride Vapor Phase Epitaxy ◽  
Structural Defects ◽  
Accurate Estimation ◽  
Plan View ◽  
Atomic Force ◽  
Transmission Electron

ABSTRACTThe availability of reliable and quick methods to investigate defects in GaN films is of great interest. Photo-electrochemical (PEC), and hot wet etching using both H3PO4 acid and molten KOH have been used to study structural defects in GaN layers grown by hydride vapor phase epitaxy and molecular beam epitaxy. The purpose of this work is to determine whether, and under what conditions, these different methods of investigation are consistent and to get to a more accurate estimation of the defect density. As-grown and etched surfaces were investigated by atomic force microscopy (AFM), and plan-view and cross-sectional transmission electron microscopy (TEM). Free-standing whisker-like features and hexagonal etch pits were formed on the etched sample surfaces by PEC and wet etching, respectively. Using plan-view AFM, we found the density of whiskers (8x108-1×109 cm−2) to be similar to the etch pit densities when etched in both H3PO4 and molten KOH under precise etching conditions. During the wet etching process, a careful balance must be struck to ensure that every defect is delineated, but not overetched to cause merging which would lead to an underestimation of the defect density. Additionally, TEM observations confirmed the dislocation densities obtained by etching, which increased our confidence in the consistency of the methods used.

Influence of Heat Treatments on Microstructures in an Fe-Co-V Alloy

1974 ◽  
Vol 32 ◽  
pp. 512-513
Author(s):  
S. Mahajan ◽  
M. R. Pinnel ◽  
J. E. Bennett
Keyword(s):  
Single Phase ◽  
Alloy Composition ◽  
Supersaturated Solid Solution ◽  
Cell Formation ◽  
Heat Treatments ◽  
Air Cooling ◽  
Iced Brine ◽  
Transmission Electron ◽  
The Matrix ◽  
Bcc Structure

The microstructural changes in an Fe-Co-V alloy (composition by wt.%: 2.97 V, 48.70 Co, 47.34 Fe and balance impurities, such as C, P and Ni) resulting from different heat treatments have been evaluated by optical metallography and transmission electron microscopy. Results indicate that, on air cooling or quenching into iced-brine from the high temperature single phase ϒ (fcc) field, vanadium can be retained in a supersaturated solid solution (α2) which has bcc structure. For the range of cooling rates employed, a portion of the material appears to undergo the γ-α2 transformation massively and the remainder martensitically. Figure 1 shows dislocation topology in a region that may have transformed martensitically. Dislocations are homogeneously distributed throughout the matrix, and there is no evidence for cell formation. The majority of the dislocations project along the projections of <111> vectors onto the (111) plane, implying that they are predominantly of screw character.

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