Cathodoluminescence Study of Ammonothermal GaN Crystals

2012 ◽  
Vol 725 ◽  
pp. 63-66 ◽  
Author(s):  
Vanesa Hortelano ◽  
Oscar Martínez ◽  
Juan Jiménez ◽  
Bu Guo Wang ◽  
S. Swider ◽  
...  
Keyword(s):  
Point Defects ◽  
Crystal Quality ◽  
Extended Defects ◽  
Defects And Impurities ◽  
Spectrally Resolved ◽  
Supercritical Ammonia ◽  
Cathodoluminescence Study

GaN crystals grown in supercritical ammonia by the ammonothermal method were studied by cathodoluminescence (CL), both in image and spectrally resolved modes. The main extended defects and the incorporation of point defects and impurities in different growth sectors were revealed. The influence of the seeds, the role of the growth planes and the changes in the crystal quality during the growth run are discussed.

Hydrogen Interaction with Point Defects in the Si-SiO2 Structures and its Influence on the Interface Properties

2007 ◽  
Vol 131-133 ◽  
pp. 345-350 ◽  
Author(s):  
Daniel Kropman ◽  
E. Mellikov ◽  
Tiit Kärner ◽  
Ü. Ugaste ◽  
Tony Laas ◽  
...  
Keyword(s):  
Point Defects ◽  
Hydrogen Adsorption ◽  
Impurity Content ◽  
Magnetic Interaction ◽  
Interface Properties ◽  
Extended Defects ◽  
Oxidation Condition ◽  
Paramagnetic Impurities ◽  
Defects And Impurities ◽  
P Type

The type and density of the point defects that are generated in the Si surface layer during thermal oxidation depend on the oxidation condition: temperature, cooling rate, oxidation time, impurity content. Interaction between the point defects with extended defects and impurities affects the SiO2 structure and Si-SiO2 interface properties. Hydrogen adsorption on n- and p- type wafers is different. One possible reason for that can be the strength of the magnetic interaction between the hydrogen and paramagnetic impurities of the adsorbent. The influence of point defects and impurities may be diminished and the interface properties improved by an appropriate choice of the oxidation conditions and postoxidation laser irradiation.

Interaction between point defects, extended defects and impurities in the Si–SiO2 system during the process of its formation

2004 ◽  
Vol 459 (1-2) ◽  
pp. 53-57
Author(s):  
D Kropman ◽  
T Kärner ◽  
U Abru ◽  
Ü Ugaste ◽  
E Mellikov
Keyword(s):  
Point Defects ◽  
Extended Defects ◽  
Sio2 System ◽  
Defects And Impurities

Point and Extended Defect Interactions in Silicon

1997 ◽  
Vol 469 ◽  
Author(s):  
M. E. Law ◽  
S. K. Earles
Keyword(s):  
Point Defects ◽  
Quantitative Model ◽  
Extended Defects ◽  
Form Complex ◽  
Extended Defect ◽  
Enhanced Diffusion ◽  
Defect Interactions ◽  
Short Time ◽  
Surface Sink

ABSTRACTTransient Enhanced Diffusion (TED) is one of the biggest modeling challenges present in predicting scaled technologies. Damage from implantation of dopant ions changes the diffusivities of the dopants and precipitates to form complex extended defects. Developing a quantitative model for the defect behavior during short time, low temperature anneals is a key to explaining TED. The surface can play a defining role in the removal of point defects from the bulk, but there is a lot of controversy over the role and strength of the surface sink for point defects. The controversy will be reviewed, and new experimental results will be presented that investigate the role of the surface on TED.

Point Defects Interaction with Extended Defects and Impurities and its Influences on the Si-SiO2 System Properties

2005 ◽  
Vol 864 ◽  
Author(s):  
D. Kropman ◽  
U. Abru ◽  
T. Kärner ◽  
U. Ugaste ◽  
E. Mellikov ◽  
...  
Keyword(s):  
Surface Layer ◽  
Cooling Rate ◽  
Thermal Oxidation ◽  
Point Defects ◽  
Impurity Content ◽  
Interface Properties ◽  
Extended Defects ◽  
Oxidation Condition ◽  
Defects And Impurities ◽  
System Properties

AbstractThe type and density of the point defects that are generated in the Si surface layer during thermal oxidation depend on the oxidation condition: tempertature, cooling rate, oxidation time, impurity content. The interaction between point defects with extended defects and impurities affect the Si-SiO2 interface properties. The influences of point defects may be diminished and the interface properties improved by an appropriate choice of oxidation conditions.

Interaction between point defects, extended defects and impurities in the Si–SiO2 system during the process of its formation

2004 ◽  
Vol 114-115 ◽  
pp. 295-298
Author(s):  
D. Kropman ◽  
T. Kärner ◽  
U. Abru ◽  
Ü. Ugaste ◽  
E. Mellikov ◽  
...  
Keyword(s):  
Point Defects ◽  
Extended Defects ◽  
Sio2 System ◽  
Defects And Impurities

Point Defects Interaction with Extended Defects and Impurities and Its Influence on the Si-SiO2 System Properties

2005 ◽  
Vol 108-109 ◽  
pp. 333-338
Author(s):  
Daniel Kropman ◽  
U. Abru ◽  
Tiit Kärner ◽  
U. Ugaste ◽  
E. Mellikov ◽  
...  
Keyword(s):  
Surface Layer ◽  
Cooling Rate ◽  
Thermal Oxidation ◽  
Point Defects ◽  
Impurity Content ◽  
Interface Properties ◽  
Extended Defects ◽  
Oxidation Condition ◽  
Defects And Impurities ◽  
System Properties

The type and density of the point defects that are generated in the Si surface layer during thermal oxidation depend on the oxidation condition: temperature, cooling rate, oxidation time, impurity content. The interaction between point defects with extended defects and impurities affect the Si-SiO2 interface properties. The influence of point defects may be diminished and the interface properties improved by an appropriate choice of oxidation conditions.

Microstructural Evolution in Reduced TiO2

1981 ◽  
Vol 39 ◽  
pp. 74-75
Author(s):  
W. T. Donlon ◽  
S. Shinozaki ◽  
E. M. Logothetis ◽  
W. Kaizer
Keyword(s):  
Microstructural Evolution ◽  
Point Defects ◽  
Extended Defects ◽  
Small Deviations ◽  
Controlled Atmospheres ◽  
Limited Solubility ◽  
Thin Foils ◽  
Heat Treated ◽  
Porous Polycrystalline ◽  
Crystallographic Shear

Since point defects have a limited solubility in the rutile (TiO2) lattice, small deviations from stoichiometry are known to produce crystallographic shear (CS) planes which accomodate local variations in composition. The material used in this study was porous polycrystalline TiO2 (60% dense), in the form of 3mm. diameter disks, 1mm thick. Samples were mechanically polished, ion-milled by conventional techniques, and initially examined with the use of a Siemens EM102. The electron transparent thin foils were then heat-treated under controlled atmospheres of CO/CO2 and H2 and reexamined in the same manner.The “as-received” material contained mostly TiO2 grains (∼5μm diameter) which had no extended defects. Several grains however, aid exhibit a structure similar to micro-twinned grains observed in reduced rutile. Lattice fringe images (Fig. 1) of these grains reveal that the adjoining layers are not simply twin related variants of a single TinO2n-1 compound. Rather these layers (100 - 250 Å wide) are alternately comprised of stoichiometric TiO2 (rutile) and reduced TiO2 in the form of Ti8O15, with the Ti8O15 layers on either side of the TiO2 being twin related.

Fine structure and properties of defects in naturally occurring silicates and oxides

1990 ◽  
Vol 48 (4) ◽  
pp. 460-461
Author(s):  
David R. Veblen
Keyword(s):  
Chemical Reactions ◽  
High Resolution Electron Microscopy ◽  
Extended Defects ◽  
Single Chain ◽  
Naturally Occurring ◽  
Resolution Electron ◽  
Fine Structures ◽  
Image Simulations ◽  
Similar Crystal Structure

Extended defects and interfaces control many processes in rock-forming minerals, from chemical reactions to rock deformation. In many cases, it is not the average structure of a defect or interface that is most important, but rather the structure of defect terminations or offsets in an interface. One of the major thrusts of high-resolution electron microscopy in the earth sciences has been to identify the role of defect fine structures in reactions and to determine the structures of such features. This paper will review studies using HREM and image simulations to determine the structures of defects in silicate and oxide minerals and present several examples of the role of defects in mineral chemical reactions. In some cases, the geological occurrence can be used to constrain the diffusional properties of defects.The simplest reactions in minerals involve exsolution (precipitation) of one mineral from another with a similar crystal structure, and pyroxenes (single-chain silicates) provide a good example. Although conventional TEM studies have led to a basic understanding of this sort of phase separation in pyroxenes via spinodal decomposition or nucleation and growth, HREM has provided a much more detailed appreciation of the processes involved.

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