A Comparative Study of Thin-Film and Bulk Reaction Kinetics and Diffusion Path: the Ir/GaAs System

1988 ◽  
Vol 144 ◽  
Author(s):  
Kevin J. Schulz ◽  
Y. Austin Chang
Keyword(s):  
Thin Film ◽  
Reaction Kinetics ◽  
Equilibrium Phase ◽  
Bulk Diffusion ◽  
Diffusion Path ◽  
Phase Sequence ◽  
Bulk Reaction ◽  
Diffusion Paths ◽  
Kinetics Of ◽  
And Diffusion

ABSTRACTControl of the structure and chemistry at the interfaces of compound semiconductors is essential for the commercial use of these materials in electronic and optical technologies. This can only be achieved when the governing thermodynamics and kinetics of interfacial reactions are understood. Based primarily on the experience of metal/Si interactions, however, a prevailing belief was born that thin-film reactions follow a separate set of thermodynamic and kinetic “rules” which are different from bulk reactions. The intent of our work has been to not only characterize metal/GaAs contact reactions but also to rationalize these reactions with equilibrium phase diagrams and bulk metal/GaAs diffusion couple experiments. Through this approach, a better understanding of thin-film and bulk differences has been obtained.The Ir/GaAs system is used as an example. Phase formation and reaction kinetics were studied for 30 nm Ir films on (100) GaAs using TEM, XTEM, and AEM. Bulk diffusion between 0.25 mm thick Ir foil and (100) GaAs wafers was studied with SEM and electron probe microanalysis (EPMA). The diffusion paths and kinetics were the same for thin-film and bulk. The phase sequence Ir/IrGa/IrAs2/GaAs formed for all diffusion couples. Reaction kinetics were parabolic with an activation energy of 3.0 eV for both thin-film and bulk, and the data was colinear in an Arrhenius plot. Reacted layer morphology in both cases was layered. The effects of grain size, crystallographic texturing, and the relative diffusivities of the components on the reaction mechanisms in bulk versus thin-film reactions are considered.

Thermodynamic Aspects of Diffusion Paths in Ternary Systems

2007 ◽  
Vol 263 ◽  
pp. 135-140 ◽  
Author(s):  
Tony Laas ◽  
Ü. Ugaste ◽  
J. Priimets
Keyword(s):  
Thermodynamic Properties ◽  
Ternary Systems ◽  
Diffusion Path ◽  
Experimental Investigations ◽  
Ideal System ◽  
Diffusion Paths ◽  
Interdiffusion Coefficients ◽  
The Relationship ◽  
And Diffusion ◽  
Specific Influence

Description of diffusion paths is one of the most interesting and topical problems in experimental investigations of interdiffusion in multicomponent systems and, particularly, in ternary systems. The relationship between effective interdiffusion coefficients and diffusion paths in ternary systems has been discussed earlier but the specific influence of the mobility and thermodynamic properties of components on the characteristics of the diffusion path is still unclear. In this paper an attempt is made to clarify the separate influences of mobility and thermodynamics on the behavior of diffusion paths in ternary systems and the corresponding correlation is found. It is shown that in most cases the deviation of the diffusion path from linearity (an ideal system) is related to the deviation of the thermodynamic properties from the ideal. The results obtained are analyzed on the basis of thermodynamic data for the ternary system Cu-Fe-Ni.

Reactions between palladium and gallium arsenide: Bulk versus thin-film studies

1988 ◽  
Vol 3 (1) ◽  
pp. 148-163 ◽  
Author(s):  
J. -C. Lin ◽  
K. -C. Hsieh ◽  
K. J. Schulz ◽  
Y. A. Chang
Keyword(s):  
Thin Film ◽  
Phase Formation ◽  
Ternary Phase ◽  
Film Studies ◽  
Bulk Diffusion ◽  
Diffusion Path ◽  
Solution Phase ◽  
Stable Configuration ◽  
Diffusion Couples ◽  
Initial Formation

Reactions between Pd and GaAs have been studied using bulk-diffusion couples of Pd (∼0.6 mm thick) /GaAs and thin-film Pd (50 and 160 nm)/GaAs samples. The sequence of phase formation at 600°C between bulk Pd and GaAs was established. Initial formation of the solution phase μ and the ternary phase T does not represent the stable configuration. The stable configuration is GaAs |∊|Λ|γ|ν|Pd and is termed the diffusion path between GaAs and Pd. The sequence of phase formation for the bulk-diffusion couples is similar at 500°C. Phase formation for the thin-film Pd/GaAs specimens was studied at 180,220,250,300,350,400,450,600, and 1000°C for various annealing times. The sequence of phase formation obtained from the thin-film experiments is rationalized readily from the known ternary phase equilibria of Ga–Pd–As and the results from the bulk-diffusion couples of Pd/GaAs. The thin-film results reported in the literature are likewise rationalized. The diffusion path concept provides a useful guide in understanding the phase formation in Pd–GaAs interface or any other M-GaAs interface. This information is important in designing a uniform, stable contact for the metallization of GaAs.

scholarly journals Research on the Influencing Factors of Brand Diffusion via Social Media

2020 ◽  
Vol 189 ◽  
pp. 03032
Author(s):  
Peng Yunan ◽  
Wang Zongshui ◽  
Zhang Jian
Keyword(s):  
Social Media ◽  
Diffusion Path ◽  
Impact Factors ◽  
Audience Participation ◽  
Factors Influencing ◽  
Diffusion Paths ◽  
Main Factors ◽  
The Impact ◽  
And Diffusion ◽  
Content Information

[Purpose] The paper aims to identify the impact factors of brand diffusion via social media. It provides a theoretical reference for enterprises to choose social media and improves brand influence. [Method] First, we summarize the general path of brand diffusion through social media by studying the relevant literatures. Next, four popular social media WeChat, Weibo, Tiktok, and Taobao have been selected as research samples to analyze the different brand diffusion paths. Finally, we summarize the impact of brand diffusion on social media according to the paths. [Results] The result shows that the main factors influencing brand diffusion on social media are diffusion content, information credibility, audience participation, and diffusion path.

Differences Between the Growth Kinetics of Thin Film and Bulk Diffusion Couples

1981 ◽  
Vol 10 ◽  
Author(s):  
U. Gösele ◽  
K. N. Tu
Keyword(s):  
Thin Film ◽  
Equilibrium Phase ◽  
Interface Reaction ◽  
Bulk Diffusion ◽  
Equilibrium Phase Diagram ◽  
Specific Reference ◽  
Second Phase ◽  
Diffusion Couples ◽  
Reaction Barriers ◽  
Equilibrium Phases

It is proposed that interface reaction barriers in binary A/B diffusion couples lead to the absence of phases predicted by the equilibrium phase diagram, provided that the diffusion zones are sufficiently thin (“thin film case”). With increasing thickness of the diffusion zones the influence of interface reaction barriers decreases and the simultaneous existence of diffusion-controlled growth of all equilibrium phases is expected (“bulk case”). First-phase and different modes of second-phase formation in the diffusion zones as well as the influence of impurities are discussed with specific reference to silicide formation. For this discussion the concept of a critical thickness of the first forming phase is introduced, below which a second compound phase cannot grow simultaneously with the first one.

scholarly journals Experimental analysis and modelling of temperature- and humidity-controlled curing

2021 ◽  
Author(s):  
Rebecca Jennrich ◽  
Ahmet Burak Aydogdu ◽  
Alexander Lion ◽  
Michael Johlitz ◽  
Sarah Glaser ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Reaction Kinetics ◽  
Experimental Analysis ◽  
Hardening Process ◽  
Complex Hardening ◽  
Degree Of Curing ◽  
Kinetics Of ◽  
And Diffusion ◽  
Coupled Reaction

AbstractThere has been much discussion about modelling the reaction kinetics of a curing polymer. Typically, curing is described by the development of a variable called degree of curing as a function of temperature and time. The material considered in this paper exhibits two different curing mechanisms, namely temperature-activated and diffusion-based. To be able to describe the complex hardening process, the material is extensively analysed experimentally, and a thermodynamically consistent coupled reaction kinetics model is formulated based on experimental observations. This model enables the implementation of the thermal, caloric, and mechanical properties of the material into a finite element (FE) framework.

Nb Contacts to GaAs: Thermal Stability and Phase Formation

1987 ◽  
Vol 108 ◽  
Author(s):  
Kevin J. Schulz ◽  
Xiang-Yun Zheng ◽  
Y. Austin Chang
Keyword(s):  
Thin Film ◽  
Thermal Stability ◽  
Film Studies ◽  
Bulk Diffusion ◽  
Diffusion Path ◽  
Diffusion Couples ◽  
Compound Formation ◽  
The Stability ◽  
Binary Compounds ◽  
Thermal Stability Of

ABSTRACTThe applicability of Nb as a Schottky barrier on GaAs depends to a large extent on the thermal stability of the contacts. In this study, bulk diffusion couple and phase diagram studies in addition to thin film studies were completed to understand the stability of and the reactions at the Nb/GaAs interface. Nb thin films were deposited onto GaAs substrates by dc magnetron sputtering and were annealed in the temperature range 300 to 1000°C. Analysis was done using plan-TEM and XTEM. The Nb/GaAs interface was found to break down into a series of binary compounds above 500°C. Bulk diffusion couples annealed at 600°C were analyzed using an electron microprobe. The stable sequence of phases formed in the couple, i.e., the diffusion path, was determined and was used to rationalize the observed compound formation in the thin film contact system.

scholarly journals Неравновесные диффузионные фазовые превращения в сплавах, обусловленные миграцией границ зерен и дислокаций

2019 ◽  
Vol 61 (2) ◽  
pp. 346
Author(s):  
И.К. Разумов ◽  
Ю.Н. Горностырев ◽  
А.Е. Ермаков
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Equilibrium Phase ◽  
Bulk Diffusion ◽  
Structural Instability ◽  
Regular Structures ◽  
Proposed Model ◽  
Nonequilibrium States ◽  
The Difference ◽  
And Diffusion

AbstractThe main scenarios of nonequilibrium diffusional transformations induced by moving defects (dislocations, grain boundaries) in alloys under severe plastic deformation are considered. It has been shown that the phase state locally changes in the area of a defect where thermodynamic properties of alloy are locally changed, and the attained state is frozen after the displacement of a defect due to the difference between the rates of bulk diffusion and diffusion on a defect. For this reason, an alloy shifts from the state of its thermodynamic equilibrium under treatment, thus different nonequilibrium states, such as the disordering of alloy, the dissolution of equilibrium phase precipitates, the appearance of nonequilibrium phases, and the formation of regular structures, are possible depending on the type of the system. These effects may take place if the treatment of an alloy is performed at moderate temperatures, when diffusion is frozen in the bulk and rather active on defects. The phenomena of phase and structural instability developing under severe plastic deformation at moderate temperatures are considered within the framework of the proposed model.

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