The surface diffusion of Ga species on an AlGaN facet structure in low pressure MOVPE

ABSTRACTFacet structures of GaN grown by epitaxial lateral overgrowth (ELO) via low pressure-metalorganic vapor phase epitaxy (LP-MOVPE) are controlled by growth conditions such as reactor pressure and growth temperature, where this technique is called FACELO (Facet Controlled ELO). The mechanism of the morphological change is discussed based on stability of the surface atoms. The propagation mechanism of the threading dislocations for the different GaN facet structure is also investigated. The distribution and density of the threading dislocations are observed by the growth pit density (GPD) method. Two typical models employing the FACELO are proposed; in one model, the dislocation concentrates only on the window area and, in the other model, only in the coalescence region in the center of the mask. In the latter model, the dislocation density is dramatically dropped to the order of 105−6 cm−2 with good reproducibility.

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The surface diffusion of Ga on an AlGaN/GaN facet structure in the MOVPE growth

physica status solidi (c) ◽

10.1002/pssc.200303511 ◽

2003 ◽

Vol 0 (7) ◽

pp. 2154-2158 ◽

Cited By ~ 5

Author(s):

Tetsuo Narita ◽

Toshiki Hikosaka ◽

Yoshio Honda ◽

Masahito Yamaguchi ◽

Nobuhiko Sawaki

Keyword(s):

Surface Diffusion ◽

Facet Structure ◽

Movpe Growth

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Transformation of GaAs (001)–(111)B facet structure by surface diffusion during molecular beam epitaxy on patterned substrates

Journal of Crystal Growth ◽

10.1016/s0022-0248(01)00633-9 ◽

2001 ◽

Vol 227-228 ◽

pp. 62-66 ◽

Cited By ~ 5

Author(s):

S Koshiba ◽

Y Nakamura ◽

T Noda ◽

S Watanabe ◽

H Akiyama ◽

...

Keyword(s):

Molecular Beam Epitaxy ◽

Surface Diffusion ◽

Molecular Beam ◽

Patterned Substrates ◽

Facet Structure

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Unified Model for Ballistic Transport and Gas-Solid Reactions in Features

MRS Proceedings ◽

10.1557/proc-204-375 ◽

1990 ◽

Vol 204 ◽

Author(s):

T. S. Cale ◽

G. B. Raupp ◽

T. H. Gandy

Keyword(s):

Surface Diffusion ◽

Ballistic Transport ◽

Three Dimensional ◽

Low Pressure ◽

Unified Model ◽

Governing Equations ◽

Adsorbed Species ◽

Molecular Velocity ◽

Patterned Wafers

ABSTRACTThe three dimensional equations which govern free molecular or ballistic transport and heterogeneous gas-solid reactions in features on patterned wafers during low pressure processing are reviewed. The governing equations specific to long rectangular trenches are extended to include nonuniform molecular velocity distributions in the source volume above the wafer as well as surface diffusion of adsorbed species or intermediates. Introduction of reaction stoichiometries and kinetic expressions for general deposition and etch reactions completes the specification of the problem. Local generalized sticking factors arise in the process of nondimensionalizing the governing equations.

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Effects of Electrical Discharges in Low Pressure Gases on the Morphology of Polyethylene Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052730 ◽

1974 ◽

Vol 32 ◽

pp. 544-545

Author(s):

L.H. Bolz ◽

D.H. Reneker

Keyword(s):

Power Distribution ◽

Electrical Discharge ◽

Dielectric Breakdown ◽

Ionic Species ◽

Low Pressure ◽

Polymer Surfaces ◽

Electrical Discharges ◽

Adhesive Bonds ◽

Power Distribution Lines ◽

Modification Of The Surface

The attack, on the surface of a polymer, by the atomic, molecular and ionic species that are created in a low pressure electrical discharge in a gas is interesting because: 1) significant interior morphological features may be revealed, 2) dielectric breakdown of polymeric insulation on high voltage power distribution lines involves the attack on the polymer of such species created in a corona discharge, 3) adhesive bonds formed between polymer surfaces subjected to such SDecies are much stronger than bonds between untreated surfaces, 4) the chemical modification of the surface creates a reactive surface to which a thin layer of another polymer may be bonded by glow discharge polymerization.

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Field ion microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104236 ◽

1988 ◽

Vol 46 ◽

pp. 434-435

Author(s):

Gert Ehrlich

Keyword(s):

Low Temperature ◽

Sample Surface ◽

Low Pressure ◽

Radius Of Curvature ◽

Field Ion Microscopy ◽

Phosphor Screen ◽

Ion Microscopy ◽

Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

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A theory of contamination in electron microscopes by surface diffusion

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107721 ◽

1978 ◽

Vol 36 (1) ◽

pp. 116-117

Author(s):

J.T. Fourie

Keyword(s):

Electron Beam ◽

Surface Diffusion ◽

High Vacuum ◽

Ultra High Vacuum ◽

Physical Parameters ◽

Carbon Compounds ◽

Hydrocarbon Molecules ◽

Electron Microscopes ◽

Primary Electrons ◽

Long Chain

Contamination in electron microscopes can be a serious problem in STEM or in situations where a number of high resolution micrographs are required of the same area in TEM. In modern instruments the environment around the specimen can be made free of the hydrocarbon molecules, which are responsible for contamination, by means of either ultra-high vacuum or cryo-pumping techniques. However, these techniques are not effective against hydrocarbon molecules adsorbed on the specimen surface before or during its introduction into the microscope. The present paper is concerned with a theory of how certain physical parameters can influence the surface diffusion of these adsorbed molecules into the electron beam where they are deposited in the form of long chain carbon compounds by interaction with the primary electrons.

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