Dislocations In Germanium Research Articles

Internal Friction Phenomena Connected with Either Edge or Screw Dislocations in Germanium

Internal friction measurements were carried out on germanium specimens with either edge or screw dislocations. The Kessler peak and logarithmic trend were checked with the edge character specimens. The screw character specimens showed two new peaks and another logarithmic stage, all characterized by low activation energies. A logarithmic dependence of the peak temperature on the dislocation density was also observed. Under certain conditions, regarding the kink distance dependence on dislocation density and on pinning lengths, the results concerning the screw dislocations may be interpreted in terms of smooth kink-free motion while the edge dislocation phenomena can be explained on the basis of damping mechanisms depending on interactions between either kinks and dragging points or point defects and dislocations.

X-ray Diffraction Topography of Germanium Wafers

X-ray diffraction topography in transmission and reflection has been employed to analyze crystal faults and stresses in germanium wafers caused by deposition of oxide layers, epitaxy and planar diffusion. Localized diffusion of arsenic, gallium and phosphorus normally does not introduce stresses sufficiently high to generate dislocations in germanium (011) wafers. However, heat treatment of germanium wafers covered with a SiO2 film causes high stresses which are often relieved by plastic deformation.

Cyclotron Resonance of Plastically Deformed Germanium

A cyclotron resonance study of electron scattering by edge-type dislocations in germanium has been carried out at liquid helium temperatures. The static deformation potential due to the dilatational strain around the dislocation is taken as the scattering potential and the resonance linewidth is calculated through a procedure similar to that taken by Kawamura et al. for the carrier-carrier interaction. The experimental results are qualitatively well explained by this treatment. The lower limit of the radial integration which determines the second moment of the resonance line gives a measure of the “critical radius” around a dislocation, within which the electron lifetime becomes extremely short owing to the capture effect of the dislocation.

Dangling Bonds and Dislocations in Semiconductors

Experimentally, dislocations in germanium have a negative core charge due to the filling of some acceptor states. These states do not appear to be related directly to "dangling bonds," since the charge is similar in screw and edge dislocations. A one-dimensional model is investigated in which a small amount of free volume, to represent the core of the dislocation, is inserted into a ring of $N$ atomic potentials. In this model it is found (a) there is a localized state in the gap; (b) it is pulled out of the upper "conduction" band, in agreement with the sign of the core charge; (c) the localized state exists whether there are bonding states below the gap and antibonding above, or vice versa, and thus is not related to the Shockley condition for a surface state; (d) the cause of the extra state is the local decrease in atom density.

Cyclotron resonance study of electron scattering by dislocations in germanium

A human primary prostatic adenocarcinoma cell line named ND-1 has been established in long term tissue culture. The cultured cells show growth in both monolayers and in soft agar suspension and produce subcutaneous tumors in nude mice. Cytogenetic analysis by G-banding demonstrated an aneuploid karyotype with a modal chromosome number of 62, and multiple marker chromosomes with 25-30% structural abnormalities. Ploidy analysis revealed that the majority of ND-1 cells (67%) had a DNA mass of 10.1 picogram and DNA index of 1.41. Nineteen percent of cells had a DNA mass of 21.3 picogram and DNA index of 3.0. Electron microscopic studies revealed common features of neoplastic epithelial cells such as numerous microvilli, junctional complexes, abnormal nuclei, nucleoli, and mitochondria. Due to the absence of a structurally normal Y chromosome, confirmation of the presence of a derived Y chromosome was achieved through the use of C-banding and through fluorescent in situ hybridization with a Y chromosome repeat probe. Tandem E PSA immunoenzymatic assay revealed that these ND-1 cells secrete small amounts of prostate specific antigen.

Mechanism of radiative recombination at dislocations in germanium: A. A. Gippius and V. S. Vavillov (Vol. 6, No. 8, pp. 2361–2368)

Mechanism of radiative recombination at dislocations in germanium: A. A. Gippius and V. S. Vavillov (Vol. 6, No. 8, pp. 2361–2368)

Determination of the yield of recombination radiation associated with dislocations in germanium

Determination of the yield of recombination radiation associated with dislocations in germanium

Theory of Carrier Recombination at Dislocations in Germanium

AbstractOn the basis of Read's dislocation model, a theory of the recombination of carriers in n‐type germanium is developed, including both the transient and steady state. The starting point for the present considerations is the assumption that the carrier capture cross‐sections are dependent on the charge density of the dislocation line, an idea similar to that given previously by Morrison. The theory deals mainly with temporary trapping of holes (a phenomenon which was observed recently in plastically deformed germanium) and yields good agreement with experiment.

Direct observations of the geometry of defects in germanium

Abstract Transmission electron microscope studies of germanium deformed at strain rates that were large relative to the temperature of deformation showed the dislocations to be straight and aligned along and directions. All of the simple combinations of Burgers vector and line direction were encountered except two. Numerous T joins and elbows were found at which the line tensions were not balanced. Two types of dislocation dipole were found, namely pairs of dislocations aligned along directions and pairs of dislocations aligned along directions. The two types of dipole were equally numerous. Forty-five small angle boundaries were observed of which eleven were on {111} planes, thirteen were on {112} planes, eleven were on {110} planes, six were stepped and only four were curved. Sharp dislocation walls were formed even when the boundaries were not planar. The results are discussed in relation to geometrical models of dislocations in germanium and in terms of kink theories of disloca...

Verzerrung anisotroper K�rper durch Versetzungen mit Anwendung auf die Berechnung der R�ntgenintensit�t

An elastic state in arbitrarily anisotropic cylinders is considered for the case in which the displacement does not vary in the direction of the axis. The first and second boundary-value problem are solved for the half-plane and the infinite plane with an elliptic hole as cross sections of the cylinders. With the aid of these solutions one can treat further domains by the method of successive approximation. For a general cross section the problem leads to a system of integral equations. The strain fields about straight dislocation lines parallel to the surface (which may be free from applied stress) are special cases of the treated state of deformation. The solution is given for 1) dislocations in a half-space, 2) dislocations in an infinite plate (through a recursion formula), 3) a dislocation in an infinite solid out of which an elliptic cylinder is cut containing the dislocation line. — From the strain one obtains a formula for the intensity distribution of X-rays reflected under certain conditions by a dislocation parallel to the surface of a half-space. Numerical results are given for two dislocations in Germanium.

Erratum: Velocities and Densities of Dislocations in Germanium and Other Semiconductor Crystals

Erratum: Velocities and Densities of Dislocations in Germanium and Other Semiconductor Crystals

The dynamical behaviour of dislocations in germanium

The dynamical behaviour of dislocations in germanium

Velocities and Densities of Dislocations in Germanium and Other Semiconductor Crystals

The average velocities of dislocations have been measured in four semiconductor crystals-silicon, germanium, gallium antimonide, and indium antimonide. The range of measured velocities was between 10−6 and 2×10−1 cm/sec. The dislocation velocities in these crystals are relatively insensitive to stress when compared to LiF or Si-Fe. The effect of temperature, in the range 0.5 to 0.8TM, on the velocities at various constant stresses was measured and the activation energies for the dislocation velocities were obtained in each of the crystals. No marked dependence of activation energy as a function of the applied stress was obtained. The effect of strain on the dislocation densities was measured as a function of orientation, temperature, and strain rate. It was found that even in initially dislocation-free crystals, dislocations were generated at quite low stresses. From direct measurements of etch pits and dislocation velocities it was possible to estimate the fraction of mobile dislocations. Under certain conditions the percentage of mobile dislocations was as low as 3 to 8%.

Production of Dislocations in Germanium by Thermal Shock

Dislocations introduced into single crystals of germanium grown by the Czochralski technique have been studied. It was found that most of the dislocations do not originate during growth, but are produced after growth as a result of thermal shock. Thermal stresses resulting from nonuniform temperature gradients during growth seem to have little or no effect on the dislocation density and distribution.

Dislocations in germanium and silicon

Dislocations in germanium and silicon

LIX. The Electrical Properties of Dislocations in Germanium

ABSTRACT The electron energy levels at an edge dislocation in germanium are discussed. It is shown that these levels will be considerably modified by the presence of a Cottrell impurity atmosphere. This leads to an interpretation of otherwise conflicting experimental results. Further experiments are suggested. † Communicated by the Author

A Note on the Theory of Dislocation In Germanium

A Note on the Theory of Dislocation In Germanium

Effect of Dislocations on the Minority Carrier Lifetime in Semiconductors

The density of random dislocations in germanium and silicon crystals has been measured by means of x-ray rocking curves and by etch pit counting. Data obtained by the two methods are in good agreement, and dislocation densities in the range ${10}^{4}$-${10}^{7}$/${\mathrm{cm}}^{2}$ were found. The minority carrier lifetime was shown to vary with the dislocation density, and the results could be expressed in terms of a recombination efficiency per unit length of dislocation line, ${\ensuremath{\sigma}}_{R}=\frac{1}{{N}_{D\ensuremath{\tau}}}$ (where ${N}_{D}=\mathrm{dislocation}\mathrm{density}$, $\ensuremath{\tau}=\mathrm{lifetime}$). ${\ensuremath{\sigma}}_{R}$ was found to decrease with increasing resistivity of germanium and was higher for silicon than for germanium of comparable purity.

Dislocations in Germanium

A light microscope study of etched germanium crystals has shown the dislocation distribution in them. The dislocations form a network in the crystal. The formation of small angle grain boundaries is discussed. Screw dislocations with large Burgers vectors have been found in some germanium crystals.

XVI. Scattering of electrons by charged dislocations in semiconductors

Abstract Experiments suggest that dislocations in germanium act as rows of closely spaced acceptor centres. In n-type material a dislocation accepts electrons and becomes a line of negative charge surrounded by a cylindrical region of fixed positive space charge. An array of parallel dislocations will have relatively little effect on electron mobility parallel to the dislocations. The mobility normal to the dislocations will be reduced because: (1) The space charge cylinders deflect electrons and scatter the electron momentum normal to the dislocations; this reduces mean free time. Dislocation scattering is characterized by a mean free path that depends on direction. (2) Even when the dislocations are far enough apart that the mean free time is not affected, the macroscopic mobility may be reduced because the electrons cannot drift parallel to the applied field; instead they follow curved paths winding between the space charge cylinders (which in typical cases are the order of a micron in diameter). This ...