Swirl Defects in As-Grown Silicon Crystals

1980 ◽  
Vol 2 ◽  
Author(s):  
A.J.R. de Kock
Keyword(s):  
Point Defects ◽  
Defect Formation ◽  
Growth Conditions ◽  
Floating Zone ◽  
Bulk Silicon ◽  
Czochralski Technique ◽  
Melt Growth ◽  
Silicon Crystals ◽  
Crystal Purity ◽  
Effect Of Doping

ABSTRACTDuring melt-growth of macroscopically dislocation free bulk silicon crystals (floating-zone and Czochralski technique) microdefects can form due to the condensation of thermal point defects (self-interstitials, vacancies). The formation of these imperfections, generally referred to as “swirl defects”, is strongly affected by the growth conditions (e.g. the crystal pulling rate) and crystal purity. The various reported defect formation models will be discussed. Special attention will be paid to the effect of doping on swirl defect formation.

Intrinsic Point Defects in Silicon Crystal Growth

2011 ◽  
Vol 178-179 ◽  
pp. 3-14 ◽  
Author(s):  
Vladimir V. Voronkov ◽  
Robert Falster
Keyword(s):  
Crystal Growth ◽  
Point Defects ◽  
Vacancy Concentration ◽  
Silicon Crystal ◽  
Growth Conditions ◽  
Intrinsic Point Defects ◽  
Silicon Crystals ◽  
Low Concentrations ◽  
Different Populations ◽  
Vacancy Concentrations

In dislocation-free silicon, intrinsic point defects – either vacancies or self-interstitials, depending on the growth conditions - are incorporated into a growing crystal. Their incorporated concentration is relatively low (normally, less than 1014 cm-3 - much lower than the concentration of impurities). In spite of this, they play a crucial role in the control of the structural properties of silicon materials. Modern silicon crystals are grown mostly in the vacancy mode and contain many vacancy-based agglomerates. At typical grown-in vacancy concentrations the dominant agglomerates are voids, while at lower vacancy concentrations there are different populations of joint vacancy-oxygen agglomerates (oxide plates). Larger plates – formed in a narrow range of vacancy concentration and accordingly residing in a narrow spatial band – are responsible for the formation of stacking fault rings in oxidized wafers. Using advanced crystal growth techniques, whole crystals can be grown at such low concentrations of vacancies or self-interstitials such that they can be considered as perfect.

Diffusion of Point Defects in Silicon Crystals during Melt-Growth. II -One Diffusor Model-

1993 ◽  
Vol 32 (Part 1, No. 4) ◽  
pp. 1747-1753 ◽  
Author(s):  
Ryuichi Habu ◽  
Kiyoshi Kojima ◽  
Hirohumi Harada ◽  
Azusa Tomiura
Keyword(s):  
Point Defects ◽  
Melt Growth ◽  
Silicon Crystals

Diffusion of Point Defects in Silicon Crystals during Melt-Growth. III -Two Diffusor Model-

1993 ◽  
Vol 32 (Part 1, No. 4) ◽  
pp. 1754-1758 ◽  
Author(s):  
Ryuichi Habu ◽  
Kiyoshi Kojima ◽  
Hirohumi Harada ◽  
Azusa Tomiura
Keyword(s):  
Point Defects ◽  
Melt Growth ◽  
Silicon Crystals

Vacancies in Growth-Rate-Varied CZ Silicon Crystal Observed by Low-Temperature Ultrasonic Measurements

2007 ◽  
Vol 131-133 ◽  
pp. 455-460 ◽  
Author(s):  
Hiroshi Yamada-Kaneta ◽  
Terutaka Goto ◽  
Yuichi Nemoto ◽  
Koji Sato ◽  
Masatoshi Hikin ◽  
...  
Keyword(s):  
Low Temperature ◽  
Point Defects ◽  
Vacancy Concentration ◽  
Silicon Crystal ◽  
Floating Zone ◽  
Rich Region ◽  
Silicon Crystals ◽  
Ultrasonic Measurements ◽  
Measured Distribution ◽  
Elastic Softening

The low-temperature ultrasonic experiments are performed to measure the distribution of vacancy concentration in the ingot of the Czochralski (CZ) silicon crystal grown with the pulling rate gradually lowered. The elastic softening similar to that we recently found for the floating-zone-grown silicon crystals is observed for the so-called vacancy-rich region of the ingot which contains no voids or dislocation clusters. We further uncover that the interstitial-rich region in the ingot exhibits no such elastic softening, confirming our previous conclusion that the defects responsible for the low-temperature elastic softening are the vacancies. We also disclose that the elastic softening is absent for the ring-like oxidation stacking fault (R-OSF) region of the ingot. The measured distribution of the vacancy concentration indicates that the minority point defects are perfectly cancelled by the majority point defects during the CZ crystal growth.

Diffusion of Point Defects in Silicon Crystals during Melt-Growth. I -Uphill Diffusion-

1993 ◽  
Vol 32 (Part 1, No. 4) ◽  
pp. 1740-1746 ◽  
Author(s):  
Ryuichi Habu ◽  
Isamu Yunoki ◽  
Takao Saito ◽  
Azusa Tomiura
Keyword(s):  
Point Defects ◽  
Uphill Diffusion ◽  
Melt Growth ◽  
Silicon Crystals

Effect of Laser Thermal Processing on Defect Evolution in Silicon

2002 ◽  
Vol 717 ◽  
Author(s):  
Erik Kuryliw ◽  
Kevin S. Jones ◽  
David Sing ◽  
Michael J. Rendon ◽  
Somit Talwar
Keyword(s):  
Point Defects ◽  
Thermal Processing ◽  
Defect Formation ◽  
Secondary Ion Mass Spectrometry ◽  
Laser Energy ◽  
Process Window ◽  
Loop Formation ◽  
Transmission Electron ◽  
Ultra Shallow Junctions ◽  
Laser Thermal Processing

AbstractLaser Thermal Processing (LTP) involves laser melting of an implantation induced preamorphized layer to form highly doped ultra shallow junctions in silicon. In theory, a large number of interstitials remain in the end of range (EOR) just below the laser-formed junction. There is also the possibility of quenching in point defects during the liquid phase epitaxial regrowth of the melt region. Since post processing anneals are inevitable, it is necessary to understand both the behavior of these interstitials and the nature of point defects in the recrystallized-melt region since they can directly affect deactivation and enhanced diffusion. In this study, an amorphizing 15 keV 1 x 1015/cm2 Si+ implant was done followed by a 1 keV 1 x 1014/cm2 B+ implant. The surface was then laser melted at energy densities between 0.74 and 0.9 J/cm2 using a 308 nm excimer-laser. It was found that laser energy densities above 0.81 J/cm2 melted past the amorphous-crystalline interface. Post-LTP furnace anneals were performed at 750°C for 2 and 4 hours. Transmission electron microscopy was used to analyze the defect formation after LTP and following furnace anneals. Secondary ion mass spectrometry measured the initial and final boron profiles. It was observed that increasing the laser energy density led to increased dislocation loop formation and increased diffusion after the furnace anneal. A maximum loop density and diffusion was observed at the end of the process window, suggesting a correlation between the crystallization defects and the interstitial evolution.

scholarly journals First Principles Calculations of Defects in Unstable Crystals: Austenitic Iron

2011 ◽  
Vol 1363 ◽  
Author(s):  
G.J. Ackland ◽  
T.P.C. Klaver ◽  
D.J. Hepburn
Keyword(s):  
Point Defects ◽  
First Principles ◽  
Defect Formation ◽  
Single Layer ◽  
Temperature Limit ◽  
Reference State ◽  
First Principles Calculations ◽  
General Picture ◽  
Bcc Iron ◽  
Defect Energies

ABSTRACTFirst principles calculations have given a new insight into the energies of point defects in many different materials, information which cannot be readily obtained from experiment. Most such calculations are done at zero Kelvin, with the assumption that finite temperature effects on defect energies and barriers are small. In some materials, however, the stable crystal structure of interest is mechanically unstable at 0K. In such cases, alternate approaches are needed. Here we present results of first principles calculations of austenitic iron using the VASP code. We determine an appropriate reference state for collinear magnetism to be the antiferromagnetic (001) double-layer (AFM-d) which is both stable and lower in energy than other possible models for the low temperature limit of paramagnetic fcc iron. Another plausible reference state is the antiferromagnetic (001) single layer (AFM-1). We then consider the energetics of dissolving typical alloying impurities (Ni, Cr) in the materials, and their interaction with point defects typical of the irradiated environment. We show that the calculated defect formation energies have fairly high dependence on the reference state chosen: in some cases this is due to instability of the reference state, a problem which does not seem to apply to AFM-d and AFM-1. Furthermore, there is a correlation between local free volume magnetism and energetics. Despite this, a general picture emerge that point defects in austenitic iron have geometries similar to those in simpler, non-magnetic, thermodynamically stable FCC metals. The defect energies are similar to those in BCC iron. The effect of substitutional Ni and Cr on defect properties is weak, rarely more than tenths of eV, so it is unlikely that small amounts of Ni and Cr will have a significant effect on the radiation damage in austenitic iron at high temperatures.

Hg1-xCdxTe: Defect Structure Overview

1990 ◽  
Vol 216 ◽  
Author(s):  
M.A. Berding ◽  
A. Sher ◽  
A.-B. Chen
Keyword(s):  
Point Defects ◽  
Defect Structure ◽  
Defect Formation ◽  
Activation Energies ◽  
Mass Action ◽  
Native Defect ◽  
Native Point Defects ◽  
Vacancy Migration ◽  
Formation Energies ◽  
Diffusion Activation

ABSTRACTNative point defects play an important role in HgCdTe. Here we discuss some of the relevant mass action equations, and use recently calculated defect formation energies to discuss relative defect concentrations. In agreement with experiment, the Hg vacancy is found to be the dominant native defect to accommodate excess tellurium. Preliminary estimates find the Hg antisite and the Hg interstitial to be of comparable densities. Our calculated defect formation energies are also consistent with measured diffusion activation energies, assuming the interstitial and vacancy migration energies are small.

Effect of N/Ga Flux Ratio in GaN Buffer Layer Growth by MBE on (0001) Sapphire on Defect Formation in the GaN Main Layer

1999 ◽  
Vol 572 ◽  
Author(s):  
S. Ruvimov ◽  
Z. Liliental-Weber ◽  
J. Washburn ◽  
Y. Kim ◽  
G. S. Sudhir ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Buffer Layer ◽  
Defect Formation ◽  
Flux Ratio ◽  
Growth Conditions ◽  
Buffer Layers ◽  
Simultaneous Increase ◽  
Growth Stages ◽  
Dislocation Generation ◽  
Gan Buffer Layer

ABSTRACTTransmission electron microscopy was employed to study the effect of N/Ga flux ratio in the growth of GaN buffer layers on the structure of GaN epitaxial layers grown by molecular-beamepitaxy (MBE) on sapphire. The dislocation density in GaN layers was found to increase from 1×1010 to 6×1010 cm−2 with increase of the nitrogen flux from 5 to 35 sccm during the growth of the GaN buffer layer with otherwise the same growth conditions. All GaN layers were found to contain inversion domain boundaries (IDBs) originated at the interface with sapphire and propagated up to the layer surface. Formation of IDBs was often associated with specific defects at the interface with the substrate. Dislocation generation and annihilation were shown to be mainly growth-related processes and, hence, can be controlled by the growth conditions, especially during the first growth stages. The decrease of electron Hall mobility and the simultaneous increase of the intensity of “green” luminescence with increasing dislocation density suggest that dislocation-related deep levels are created in the bandgap.

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