Rapid thermal activation and diffusion of boron and phosphorus implants

2002 ◽  
Author(s):  
A.T. Fiory ◽  
S.G. Chawda ◽  
S. Madishetty ◽  
V.R. Mehta ◽  
N.M. Ravindra ◽  
...  
Keyword(s):  
Thermal Activation ◽  
And Diffusion

Activation and Interdiffusion Characteristics in Implanted GaAs-AlGaAs Heterostructures on Si

1988 ◽  
Vol 126 ◽  
Author(s):  
S. J. Pearton ◽  
K. T. Short ◽  
K. S. Jones ◽  
S. M. Vernon
Keyword(s):  
Activation Energy ◽  
Thermal Activation ◽  
Secondary Ion Mass Spectrometry ◽  
Thermal Activation Energy ◽  
Activation Kinetics ◽  
Lattice Disorder ◽  
Si Substrates ◽  
Transmission Electron ◽  
And Diffusion ◽  
Secondary Ion

ABSTRACTThe activation kinetics and diffusion behaviour of implanted Be and Si in two different types of MOCVD-grown GaAs-AlGaAs heterostructures on Si substrates were examined by electrochemical C-V profiling, secondary ion mass spectrometry and sheet resistivity measurements. The implanted Be displays a thermal activation energy of 0.70 eV and Si a thermal activation energy of 0.53 eV in heteroepitaxial material, similar to the comparable cases in homoepitaxial GaAs. In addition, there is no evidence for enhanced diffusivity of either species, at least for implants located away from the heterointerface. The remnant lattice disorder in the heterostructures caused by implantation and annealing is negligible compared to the as-grown disorder, as revealed by transmission electron microscopy.

Modelling of catalysts and its relation to experimental problems

1992 ◽  
Vol 341 (1661) ◽  
pp. 255-268 ◽  
Keyword(s):  
Small Molecules ◽  
Active Sites ◽  
Thermal Activation ◽  
Porous Metal ◽  
Acid Sites ◽  
Zeolite Catalysts ◽  
Before And After ◽  
Porous Metal Oxides ◽  
And Diffusion

We illustrate the role of both computer simulation and the evaluation of electronic structure in the study of solid heterogeneous catalysis by reference to recent work in this laboratory on ( a ) microporous materials (that have a spatially uniform distribution of accessible active sites) and ( b ) non-porous metal oxides. Computational methodologies may be used to model, first, the structure of the uniform catalysts both before and after thermal activation, second, the docking and diffusion of molecules in solids and on their surfaces; and, third, the reaction pathways of molecules at the active site. We highlight recent successes in modelling (i) the structures of zeolitic solids, (ii) the sorption of hydrocarbons within them, (iii) the protonation of small molecules at the Bronsted acid sites in uniform solid acid (zeolite) catalysts, and (iv) the reactions of small molecules on CeO 2 and MgO surfaces.

Meridional Circulation, Turbulence, and Diffusion Processes in Stars

1976 ◽  
Vol 32 ◽  
pp. 109-116 ◽  
Author(s):  
S. Vauclair
Keyword(s):  
Convection Zone ◽  
Diffusion Processes ◽  
Meridional Circulation ◽  
Diffusion Time ◽  
Work In Progress ◽  
First Results ◽  
Stellar Envelopes ◽  
And Diffusion ◽  
Turbulence And Diffusion ◽  
Hr Diagram

This paper gives the first results of a work in progress, in collaboration with G. Michaud and G. Vauclair. It is a first attempt to compute the effects of meridional circulation and turbulence on diffusion processes in stellar envelopes. Computations have been made for a 2 Mʘstar, which lies in the Am - δ Scuti region of the HR diagram.Let us recall that in Am stars diffusion cannot occur between the two outer convection zones, contrary to what was assumed by Watson (1970, 1971) and Smith (1971), since they are linked by overshooting (Latour, 1972; Toomre et al., 1975). But diffusion may occur at the bottom of the second convection zone. According to Vauclair et al. (1974), the second convection zone, due to He II ionization, disappears after a time equal to the helium diffusion time, and then diffusion may happen at the bottom of the first convection zone, so that the arguments by Watson and Smith are preserved.

Ordering and diffusion in II-VI/III-VI alloys with structural vacancies

1997 ◽  
Vol 101-103 (1-2) ◽  
pp. 479-487
Author(s):  
H v. Wensierski
Keyword(s):  
And Diffusion
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