摘要:

Thermal fluctuations combined with moderate stress are not able to nucleate dislocations in a perfect crystal. Rather some heterogeneous nucleation (surface defects, precipitates, lattice mismatch etc.) is necessary.

ISSN:1042-0150    

DOI:10.1080/10420158908212976

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

With EPR and ENDOR hyperfine interactions with silicon and impurity nuclei have been determined for many different defects and impurity centers in silicon. A standard interpretation is mostly given with an LCAO description, as introduced into this field by Watkins and Corbett. Usually, this method only includes contributions from atomic orbitals centered on the pertinent nuclei. The anisotropic part of the hyperfine interaction arises from dipole-dipole interaction due to p-(or d-)orbitals. Only under special circumstances perceptible contributions are made by dipole-dipole interaction between nuclei and unpaired spin density which is localized at other nuclei. If this is the case, additional information on the detailed structure of the defects can be obtained. Several examples are discussed in this paper, both for vacancy-related defects and for transition metal impurities in silicon. For the vacancy we derive a lattice relaxation which is opposite to theoretical predictions.

ISSN:1042-0150    

DOI:10.1080/10420158908212977

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The effect induced by carrier trapping on the configuration and migration of defects in semiconductors are examined in light of the different predicted mechanisms.

ISSN:1042-0150    

DOI:10.1080/10420158908212978

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Photorefractive effects in LEC-grown, semi-insulating, undoped GaAs crystals were investigated. The existence of both neutral and ionized states of the EL-2 center makes this material photorefractive. However, the presence of other defects and impurities can drastically deteriorate photorefractive properties.

ISSN:1042-0150    

DOI:10.1080/10420158908212979

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The photochemical reactions of resist films consisting of poly(methyl methacrylate) (PMMA) and aromatic azide at high concentraton (25 wt.%) were studied. Both p-azidobenzoic acid (PABA) and 2,6-bis(4-azidylbenzylidene)-4-methyl cyclohexanone(2,6-bisazide) were used as the azide compounds. Chemical analysis carried out on the photoproducts of deep-UV irradiated PMMA-azide films revealed them to consist of unreacted azide compound, primary amine, azo dye, and PMMA with pendant secondary amines formed by nitrene insertion reactions. It is concluded that formation of secondary amines resulting from nitrene insertion to the PMMA chain were mainly responsible for both the dissolution rate retardation and the image reversal observed in the exposed PMMA-azide resist.

ISSN:1042-0150    

DOI:10.1080/10420158908212980

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A one semester (16 week) course is described on the use of radiation technology for undergraduate seniors and first year graduate students in the engineering, chemistry and physics disciplines. Initially the course gives a brief review of radiation (electrons, ions and photons) energy transfer and its effects on matter. A large fraction of the course deals with applications of radiation technology in a wide variety of fields such as medicine, microelectronics, metallurgy, radiation chemistry of polymers and rubber, food preservation and sterilization. Reference materials used in the course are given in the paper.

ISSN:1042-0150    

DOI:10.1080/10420158908212981

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In this review will be discussed the merits of positron annihilation as compared to “standard” methods such as electron paramagnetic responance, infrared spectroscopy and deep level transient spectroscopy as applied to various semiconductors. In the case of silicon (only) the available detailed knowledge from the “standard” methods will be compared to the positron data addressing the association of lifetime values with specific defect structures such as monovacancies and divacancies. The importance of charged states (Fermi level position), shallow traps and impurity-vacancy complexes will be emphasized. Trapping cross-sections for various defects/charged states will be discussed in the context of electron paramagnetic resonance data.

ISSN:1042-0150    

DOI:10.1080/10420158908212982

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The interaction of two hydrogen atoms in a pure silicon crystal has been studied using the MINDO/3-CCM framework and allowing for large scale lattice relaxation. Relative stabilities of various dihydrogen complexes are compared and their mobilities are discussed. The possibility of plate formation is examined.

ISSN:1042-0150    

DOI:10.1080/10420158908212983

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Persistent photocurrents were observed in semi-insulating GaAs long after the low temperature illumination with monochromatic 0.7—1.8 eV photons was terminated. These excess conductances exceed the equilibrium dark conductances up to a factor 104. We have found that the magnitude of this effect is dependent on the photosensitivity of the material, which is influenced by charge trapping effects. For various photosensitivity stages the concentration of charge trapped in deep traps was determined by measuring thermally stimulated current. Good correlation between the persistent photocurrents and the total concentration of trapped charge was found. The increase of magnitude of persistant photocurrents is interpreted as the increase of lifetime of optically created free hles due to trapping of electrons, which therefore are not available for recombination.

ISSN:1042-0150    

DOI:10.1080/10420158908212984

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The results of the EPR study of point defects configuration in silicon irradiated with high doses of electrons and neutrons (≤ 1018cm−2) are reported. It has been concluded that, under the chosen experimental conditions, the atom configuration of point defects changes as the result of impurities or Frenkel pair components being trapped by the already known defects. The other reason of changes of point defects configuration is the loss of the long range order in the lattice due to high damage concentration.

ISSN:1042-0150    

DOI:10.1080/10420158908212985

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor