摘要:

The role of dangling bonds in tetrahedrally coordinated systems is analyzed in a variety of different physical situations: tricoordinated silicon atoms at the Si—SiO2interface or in a-Si, vacancies in covalent materials or in compounds, pinning of some impurity levels, dangling bonds at surfaces and interfaces. Emphasis is put on the common features that exist in all these apparently very different situations, resulting in a fairly simple and general understanding of the related physical properties.

ISSN:1042-0150    

DOI:10.1080/10420158908212996

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Reactive ion etching always causes adynamicradiation effect to crystalline silicon, beacause of an energetic particle bombardment. RIE induced radiation effects are mostly confined to the near surface within a projected range of impinging ions, but point defects, which are highly mobile at room temperatures, can migrate further into the bulk before a damaged surface layer is etched away. Competition between etch rates and damage rates ultimately determines a degree of the RIE damage residue: the slower the etch rate, the heavier the damage may be accumulated at the near surface, eventually leading to amorphization of the surface region. Also, a removal of the surface layer due to etching or sputtering enhances a chemical reaction between a bare surface and incoming radicals. This easily forms a foreign material on the surface which gives rise to a serious contamination problem. A post-cleaning at a low temperature is highly desirable whenever the surface of active devices must be exposed to reactive plasmas.

ISSN:1042-0150    

DOI:10.1080/10420158908212997

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This paper present theoretical and experimental investigations on the influence of small geometries on latchup effects related to transient radiation effects. Since diffusion current due to ionizing radiation are proportional the square root of the diffusion constant and this quantity varies very little with doping concentrations considered here, useful expressions for radiation induced diffusion currents in VLSI components can be derived. Furthermore a method is presented by which electrical parameters can be measured in order to theoretically predict threshold values for radiation induced latchup.

ISSN:1042-0150    

DOI:10.1080/10420158908212998

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In this work the anomalous formation kinetics of old thermal donors (TD) observed in the initial stage of formation in pre-heat-treated carbon-rich samples are studied. Computer simulations applying a reaction scheme where the TD-complexes are subsequently formed by single oxygen diffusion reveal that the experimental results can only be acounted for if the pre-existing TD-core involves three oxygen atoms and has a concentration in the range 1013-1014cm−3. Carbon is found to have a major influence on the production rate of pre-existing cores.

ISSN:1042-0150    

DOI:10.1080/10420158908212999

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The diffusion length (L) of minority carriers was determined from contrast of linear defects. Dislocation contrast was measured by EBIC at room temperature versus bias of a Schottky diode. It was shown for the first time that the slope of the contrast curves depends onL. The requirement to the SEM regime and EBIC geometry were formulated in a way to avoid influence of surface recombination on the measurements and diminish the role of other side effects as well.

ISSN:1042-0150    

DOI:10.1080/10420158908213000

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The photoconductivity of semiconductors was considered under the following general conditions: the surface recombination velocity was not equal to zero, the space charge near the surface is taken into account, the value of absorption coefficient was not limited. Solving both the continuity and Poisson equations for an illuminated thick specimen, we obtained a solution which suggests a new combined measurement in order to determine various optical constants. The absorption coefficient and the diffusion length of electrons in CZ grownn-type Si (Na= 1012-1013cm−3) were measured at room temperature, using the new technique.

ISSN:1042-0150    

DOI:10.1080/10420158908213001

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A detailed deep level transient spectroscopy (DLTS) study has been carried out on a prominant hole trap at 0.34 eV above the valence band in irradiatedp-type silicon. The boron concentration in the float zone and Czochralski-grown samples varied between 1012and 1016cm−3, and irradiations with 2.0 MeV electrons have been performed at nominal room temperature to total fluences of 1.0 × 1016and 1.0 × 1017e−/cm2. The introduction rate of the trap is strongly boron-dependent, while the oxygen content in the samples does not influence neither the trap production rate nor its observed annealing behaviour. In the light of these observations and other available data on this trap, a boron-carbon pair is here tentatively proposed as the defect identity. A previously unreported hole trap at 0.45 eV above the valence band has also been observed in this work in highly boron-doped material. The isothermal and isochronal annealing characteristics of both traps have been investigated up to 400°C.

ISSN:1042-0150    

DOI:10.1080/10420158908213002

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The DX center, the lowest energy state of the donor in AIGaAs withx< 0.22, is responsible for the reduced conductivity as well as the persistent photoconductivity observed in this material at low temperature. Extensive studies of the properties of this deep level in Si-doped AIGaAs are reviewed here. Data are presented showing that the characteristics of the DX center remain essentially unchanged when it is resonant with the conduction band (x< 0.22) and that, independent of other compensation mechanisms, the DX center therefore limits the free carrier concentration in Si-doped GaAs to a maximum of about 2 × 1019cm−3. Recent measurements suggesting that the lattice relaxation involves the motion of the Si atom from the substitutional site toward an interstitial site are also presented. Evidence for the negative U model, that the DX level is the two electron state of the substitutional donor, is discussed.

ISSN:1042-0150    

DOI:10.1080/10420158908213003

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Using secondary ion mass spectrometry (SIMS) the penetration of deuterium into Si(100) substrates as a result of exposure to deuterium low pressure rf discharges has been determined as a function of exposure time, thermal contact of the Si wafers to the substrate electrode, substrate doping, and discharge pressure. For undoped (100) single crystal Si exposed without intentional heating to a 25 m torr D2plasma for 1 min the deuterium concentration in the near-surface region (0—30 nm) approaches 1021at.cm−3. It drops off with depth, but is still greater than 1017at.cm.−3at a silicon depth of 200 nm. The large penetration depth, the observation that lowering the substrate temperature decreases the rate of deuterium uptake, and the dependence of deuterium penetration on the substrate doping type indicate that hydrogen diffusion is of primary importance. The presence of a 50 nm thick oxide layer on the Si substrate during plasma exposure lowers the deuterium near-surface concentration in the Si substrate by about three orders of magnitude, while the presence of 10 nm of thermal oxide reduces the deuterium uptake only insignificantly. Heavily B and As doped polycrystalline Si show less deuterium penetration, while undoped polycrystalline Si shows more deuterium uptake than undoped single crystal Si for the same plasma treatment.

ISSN:1042-0150    

DOI:10.1080/10420158908213004

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Spatial correlations among reacting species in condensed media result from an interplay of reaction (which tends to lead to negative correlations), replacement or dissociation (which tend to produce positive correlations), and diffusion (which tends to smooth correlations out). Where correlations are high associative reactions are generally rapid. Where they are low the associative reaction is generally diminished. These characteristics of condensed phase processes have important consequences in a wide range of situations. In this paper, I review several examples drawn from radiation-physics, -chemistry, and -biochemistry of how spatial correlations determine the kinetics of reaction. Utilizing this theme, I also present two new results. I discuss a model of defect production in collision cascades in which the collective excitations during the cooling of the cascade contribute to defect recombination. A quantitative comparison with experiment is made. Lastly, I show how the kinetics of a diffusion-limitedreversiblereaction differ from a model which tacitly assumes that the spatial correlations which prevail are those of theirreversiblereaction. A connection is drawn between these models and the observed kinetics of thermal donor formation.

ISSN:1042-0150    

DOI:10.1080/10420158908213005

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor