Level set simulations of dislocation dynamics in biaxially strained, heteroepitaxial films reveal interesting kinetic and thermodynamic mechanisms for blocking the migration of threading dislocations. Two dislocations on the same or on intersecting slip planes may react to form a threading... (Read more)

The effect of open-core screw dislocations on photoluminescence in n-doped wurtzite GaN epilayer is studied computationally and compared with experimental data. A k•p Hamiltonian calculation domain is set up to contain a dipole of open-core screw dislocations, and its size... (Read more)

The interactions between edge dislocations and grain boundaries—dislocation pileup, dislocation absorption, and dislocation transmission—are studied by performing quasicontinuum simulations. The 112 asymmetrical tilt grain boundaries with different misorientation angles are used. The... (Read more)

The exact, linear response at steady state is calculated for reacting, but otherwise noninteracting, thermal defects driven by defect creation processes. The theory applies to vacancies and interstitials in the bulk, or to adatoms and advacancies on surface terraces. A wide variety of possible... (Read more)

An atomistic simulation of the threading (a+c)-mixed dislocation core in wurtzite GaN has been carried out. Starting from models generated in the framework of continuum elasticity theory, two core configurations are obtained independently by using an empirical potential and a... (Read more)

In this paper we describe the use of electron backscatter diffraction (EBSD) mapping and electron channeling contrast imaging—in the scanning electron microscope—to study tilt, atomic steps and dislocations in epitaxial GaN thin films. We show results from a series of GaN thin films of... (Read more)

We report exceptional ductile behavior in individual double-walled and triple-walled carbon nanotubes at temperatures above 2000 °C, with tensile elongation of 190% and diameter reduction of 90%, during in situ tensile-loading experiments conducted inside a high-resolution transmission... (Read more)

Plastic relaxation of carbon nanotubes under tension and at high temperature is described in terms of dislocation theory and with atomistic computer simulations. It is shown how the glide of pentagon-heptagon defects and a particular type of their pseudoclimb, with the atoms directly breaking out of... (Read more)

The authors previously reported an unusual phenomenon of strain relaxation accompanied by a reduction in threading dislocation density (TDD) on a Si_0.77Ge_0.23 layer grown on top of alternating layers of... (Read more)

The authors have observed that for In_xGa_1−xN epitaxial layers grown on bulk GaN substrates exhibit slip on the basal plane, when in the presence of free surfaces that intercept the heterointerface and for indium compositions x0.07. This leads to... (Read more)

The authors present a low voltage cathodoluminescence (CL) study of as grown GaN and GaN:Si epilayers on sapphire. At 1 kV they resolve individual threading dislocations on the sample surface at low temperature (5 K), which appear as correlated dark spots. Analysis of CL intensity profiles across... (Read more)

A detailed study of the transformation of the {113} defects into dislocation loops has been carried out in Ge preamorphized silicon (30 keV, 1×10¹⁵ Ge⁺/cm²) and annealed at 800 °C for time ranging from 15 to 2700 s. The presence of a stable defect,... (Read more)

A variable core model of a moving crystal dislocation is proposed and used to derive an expression for the Peierls stress. The dislocation width varies periodically as a dislocation moves through the lattice, which leads to an expression for the Peierls stress in terms of the difference of the total... (Read more)

The effects of dislocations and Si doping on the electrical properties of n-type GaN grown by metal organic chemical vapor deposition (MOCVD) are investigated. It is found that both electron mobility and carrier concentration are strongly influenced by edge dislocations. A moderate Si doping... (Read more)

The authors experimentally find that the thermal conductivity of gallium nitride depends critically on dislocation density using the 3-omega technique. For GaN with dislocation densities lower than 10⁶ cm^–2, the thermal conductivity is independent with dislocation... (Read more)

Synchrotron-based analytical microprobe techniques, electron backscatter diffraction, and defect etching are combined to determine the dependence of metal silicide precipitate formation on grain boundary character and microstructure in multicrystalline silicon (mc-Si). Metal silicide precipitate... (Read more)

As-grown InN is known to exhibit high unintentional n-type conductivity. Hall measurements from a range of high-quality single-crystalline epitaxially grown InN films reveal a dramatic reduction in the electron density (from low 10¹⁹ to low 10¹⁷ cm^–3)... (Read more)

The radiative recombination processes in dislocated float zone silicon samples deformed under gigapascal stresses were studied by photoluminescence (PL) spectroscopy. The observed shuffle dislocations present a reconstructed core and their generation is accompanied by the introduction of point... (Read more)

SiC bipolar devices show a degradation under forward-biased operation which has been linked with a current induced motion of one of the two glide dislocations having either Si or C core atoms. We have carried out calculations of the core structures and dynamics of partial dislocations in 3C and... (Read more)

A two-dimensional dislocation network artificially embedded in a silicon-on-insulator (SOI) layer was examined as the source of lattice strain to generate a periodic potential. A screw dislocation network with the period of 20 nm was formed in an SOI layer using a twist bonding of two SOI wafers.... (Read more)

The influence of dislocations on electron transport properties of undoped InN thin films grown by molecular-beam epitaxy on AlN(0001) pseudosubstrates is reported. The microstructure and the electron transport in InN(0001) films of varying thickness were analyzed by transmission electron microscopy... (Read more)

The strain-relaxation phenomena and the formation of a dislocation network in 2H-InN epilayers during molecular beam epitaxy are reported. Plastic and elastic strain relaxations were studied by reflection high-energy electron diffraction, transmission electron microscopy, and high resolution... (Read more)

The dislocation dependence of open circuit voltage is studied based on Donolato's model for the effect of dislocations on minority carrier effective diffusion length [J. Appl. Phys. 84, 2656 (1998)]. Experimental data measured on thin-film solar cells show a strong decrease of open circuit... (Read more)

In 1998, Donolato presented an analytical model describing the effect of dislocation density on minority carrier effective diffusion length [J. Appl. Phys. 84, 2656 (1998)]. While this analysis was derived for a "semi-infinite" specimen, our objective is the appropriate description... (Read more)

The annealing behavior of interstitial-type basal plane dislocation loops in Al ion implanted 4H-SiC is investigated. It is shown that the loops undergo a dynamical ripening process. For annealing below 1700 °C the total area of dislocation loops increases, indicating that point defects... (Read more)

The spatial distribution of strain, misfit and threading dislocations, and crystallographic orientation in uncoalesced GaN layers grown on Si(111) substrates by maskless cantilever epitaxy was studied by polychromatic x-ray microdiffraction, high resolution monochromatic x-ray diffraction, and... (Read more)

The real-time stress evolution has been investigated during molecular-beam epitaxial growth of GaAs_1–xSb_x/GaAs metamorphic buffer. These real-time data were obtained using an in situ multibeam optical sensor measurement and has been combined with... (Read more)

This paper addresses some of the fundamental issues and critical advantages in reducing the grain size/feature size to the nanoscale regime. We find that as the grain size or feature size is reduced, there is a critical size below which the defect content can be reduced virtually to zero. This... (Read more)

The impact of threading dislocation density on Ni/n-GaN Schottky barrier diode characteristics is investigated using forward biased current-voltage-temperature (I-V-T) and internal photoemission (IPE) measurements. Nominally, identical metal-organic chemical vapor... (Read more)

In this work we perform a systematic study of the dissolution of a dislocation loop layer under the influence of inert SiO₂/Si and nitrogen-rich SiO₂/Si interfaces. The composition of the dislocation loop layer was just after its formation 10%–20% Frank dislocation loops... (Read more)

An approach to precisely determine the magnitude and the sign of Burgers vectors of superscrew dislocations (including elementary screw dislocations and micropipes) in silicon carbide (SiC) single crystals has been developed. The histogram of Burgers vector values associated with micropipes follows... (Read more)

Only a few years ago, an account of degradation of silicon carbide high-voltage p-i-n diodes was presented at the European Conference on Silicon Carbide and Related Compounds (Kloster Banz, Germany, 2000). This report was followed by the intense effort of multiple groups... (Read more)

Photocapacitance and excitation photocapacitance methods were applied to reveal the dislocation-induced deep levels in coalescent epitaxial lateral overgrowth layers of InP. Point-contact Schottky barrier junctions with small junction areas were formed on dislocated and dislocation-free regions by... (Read more)

The structure and composition of threading dislocations in GaN grown by hydride vapor phase epitaxy have been examined by electron microscopy. Transmission electron microscopy showed that the core structure of screw dislocations varied widely, alternating irregularly between open core... (Read more)

Silicon carbide (SiC) has a range of useful physical, mechanical and electronic properties that make it a promising material for next-generation electronic devices^1,2. Careful consideration of the thermal conditions^3-6 in which SiC {0001} is grown has resulted in improvements in crystal diameter and quality: the quantity of macroscopic defects such as hollow core dislocations (micropipes)^7-9, inclusions, small-angle boundaries and longrange lattice warp has been reduced^10,11. But some macroscopic defects (about 1–10 cm^-2) and a large density of elementary dislocations (,10⁴ cm^-2), such as edge, basal plane and screw dislocations, remain within the crystal, and have so far prevented the realization of high-efficiency, reliable electronic devices in SiC (refs 12–16). Here we report a method, inspired by the dislocation structure of SiC grown perpendicular to the c-axis (a-face growth)¹⁷, to reduce the number of dislocations in SiC single crystals by two to three orders of magnitude, rendering them virtually dislocation-free. These substrates will promote the development of high-power SiC devices and reduce energy losses of the resulting electrical systems. (Read more)

The driving force of stacking-fault expansion in SiC p–i–n diodes was investigated using optical emission microscopy and transmission electron microscopy. The stacking-fault expansion and properties of the partial dislocations were inconsistent with any stress as the... (Read more)

We clarified the generation of process-induced dislocations around a shallow trench isolation (STI) by using convergent-beam electron diffraction. Comparing the resolved shear strain (RSS) of 12 slip systems, we found that at the trench bottom corner the RSS on slip systems (1 –1 1)[0 1 1] and... (Read more)

The ramification of micropipes is observed using scanning electron microscopy, optical microscopy, and synchrotron x-ray radiography. The conditions for the ramification of dislocated micropipes are determined theoretically within a model when the angles between dislocation lines are small. It is... (Read more)

On annealing a boron implanted Si sample at ~800 °C, boron in the tail of the implanted profile diffuses very fast, faster than the normal thermal diffusion by a factor 100 or more. After annealing for a sufficiently long time, the enhanced diffusion saturates. The enhanced diffusion is... (Read more)

Hexagonal voids observed in sublimation grown SiC boules were examined using optical microscopy, atomic force microscopy (AFM), scanning electron microscopy, KOH etching, and synchrotron white-beam x-ray topography. Voids formed at imperfections in the attachment layer between the seed and crucible... (Read more)

Experimental studies of size-related effects in silicon nanocrystals are reported. We present investigations carried out on nanocrystals prepared from single-crystal Si:P wafer by ball milling. The average final grain dimension varied depending on the way of preparation in the range between 70 and... (Read more)

Process-induced defects are still a key issue in semiconductor device production. The increasing miniaturization and number of process steps as well as the introduction of new materials and processes make the understanding of defect generation more complex. In this paper, we describe small defects... (Read more)

On the basis of ab initio calculation, we propose a new structure for the fundamental excitation of the reconstructed 30° partial dislocation in silicon. This soliton has a rare structure involving a fivefold-coordinated atom near the dislocation core. The unique electronic structure... (Read more)

Dislocation loops consisting of long and straight segments of 60? and screw parts were introduced in p-type Si by deformation under a high stress at a relatively low temperature. Electronic states associated with such dislocations were investigated by means of electric-dipole spin resonance, with... (Read more)

The observation of optically detected magnetic resonance (ODMR) signals directly correlated with dislocations in silicon is reported. The ODMR signals are identified as resonances from free electrons, dangling bonds, and quasifree holes bound to a one-dimensional potential in straight dislocations.... (Read more)

The velocity v of dislocation half-loops introduced into swirl-free floating-zone grown undoped silicon has been measured at 420°C in the resolved shear stress range 30 <τ<300 MPa. Clearly impurity atoms interact with dislocations in this material. Using the starting value of v we found the two types of 60° dislocations, which are distinguished by the sequence of their partials, to have different velocities. Furtheron the velocity depends not only on τ, but also on the elastic strain of the lattice. In the second part the papers review EPR spectroscopy of plastically deformed silicon and collects new results on the activity of dislocations in this material as trapping / recombination centers (decay of photo-EPR, photoluminescence, EBIC microscopy and photoplastic effect). (Read more)

Using deep level transient spectroscopy (DLTS) the defects introduced into silicon by plastic deformation are investigated with respect to their capture and emission characteristics. In agreement with what has been found by electron spin resonance (EPR), kind and density of the detected localized... (Read more)

Magnetic properties of the dislocation dangling bond (DDB) spin system in silicon crystals are investigated by means of the EPR technique at T = (1.3 to 150) K. Experimental results are obtained which enable one to develop a one-dimensional model of the spin system according to which the DDB chains... (Read more)

We investigated the properties of the dislocation sEPR spectra in Si in the temperature interval from 1.3 to 150ºK. At helium temperatures we observed anomalies in the behavior of the dispersion signals χ' under conditions of adiabatic rapid passage (APR) through resonance. It is shown that the spectrum of the D centers has a hyperfine (hf) structure, with a line width ∆H_i ～0.2－0.3 Oe (the distance between neighboring hf lines is of the order of their width). It is established that under ARP conditions excitations are transferred between the hf lines as a result of spin-spin interactions with a characteristic time τ₃, equal to 3－10 sec in the range 1.3－4.2ºK and weakly dependent on the temperature and on the microwave power. We measured the dependence of the integrated intensity of the absorption signals χ'' on the temperature in the 20－150ºK range. A strong deviation from the Curie low was observed at T=40－50ºK. The temperature dependence of the quantity τ₁τ₂ was measured in the same temperature range, under the assumption that the hf lines have a Lorentz shape. An anomaly at T=40－50ºK was observed also on the plot of τ₁τ₂=f(1/T). It is concluded that a magnetic phase transition takes place in the D-center system at 40－50ºK, and consequently the dislocations in Si can be regarded as models of one-demensional chain of spins with exchange interactions.

In silicon an EPR signal is produced by plastic deformation. The annealing behavior of this signal has been investigated, and the dislocation density and structure has been studied by the etch pit technique and by electron microscopy. The EPR-signal anneals in one stage with an activation energy of... (Read more)

Bei 800°C verformte Silizium-Kristalle zeigen ein Elektronenspinresonanz-Signal, dessen Intensität mit der Versetzungsdichte zunimmt. Wir vermuten, daβ dieses Signal von ungepaarten Elektronen im Kern von Versetzungen stammt. Durch die Verformung wird die Bildung von Atomgruppen in... (Read more)

Etching and copper decoration techniques have shown that silicon crystals grown from quartz crucibles under proper conditions contain no detectable dislocations.However,oxygen in concentration up to about 10¹⁸ per cm³incorporated from the quartz crucible might conceivably... (Read more)