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Review of experimental works
The growth kinetics of different silicides are investigated at different temperatures ranging from 200 – 6500 C [2, 3] under a non-irradiation process. The activation energies for the growth of these silicides are determined from the experimental measurements, and the values are shown in Table 1-1. The interdiffusion coefficients of the silicides are calculated based on the measured activation energies and temperatures at which the silicides are formed.
The growth rates of these silicides are determined from the ratio of the square of the thickness of the silicide to the annealing time. The growth rate remains constant at a particular annealing temperature. As annealing temperature changes, the growth rate changes correspondingly.
The diffusion coefficients of metal and silicon species are usually found to be smaller than the interdiffusion coefficients of the growing silicides [4]. This observation suggests that the growth of the silicide occurs at a rate faster than the diffusion of both metal and silicon species in the metal-silicon bilayer system.
The growth kinetics of the silicides is often determined as parabolic. However, there are silicides that are found to have two growth kinetics as shown in Table 1-1. Examples of such silicides are nickel silicide, tungsten disilicide and vanadium disilicide. Their growth kinetics begins as linear and later change into parabolic after a certain period of time. The thickness of silicide is generally found to increase with annealing temperature and time.
The experimental studies of the growth of silicides under irradiation are mostly carried out by ion beam mixing technique at a room temperature. The studies reveal that the stoichiometry of the silicide formed under irradiation in most cases is the same as that of the non-irradiation process. The growth kinetics of the silicide under irradiation is usually found to be similar to that of the non-irradiation process. The growth kinetics is parabolic for most of the silicides as depicted in Table 1-2.
The metal/silicon interface is usually irradiated with an ion beam to different doses at a particular ion energy. The dose dependence of mixing variance of each diffusing species is found to be the product of diffusion coefficient and irradiation time [5]. The interfacial mixing is found to increase with ion dose. The thickness of the silicide layer increases in proportion to the square root of the ion dose with nearly constant composition [6].
The growth of the silicide layer in the metal/silicon bilayer system is suggested to be due to isotropic cascade mixing, thermal spike, and radiation enhanced diffusion of both metal and silicon species. The growth of the silicide is found to depend on the fluence rate.
CHAPTER 1: INTRODUCTION
1.1 Review of experimental works
1.2 Introduction to the present theoretical approach
1.3 Aim of the research stud
1.4 The contents of the thesis
CHAPTER 2: AB COMPOUND LAYER FORMATION AS A RESULT OF CHEMICAL TRANSFORMATION CONTROLLED BY DIFFUSION
2.1 Introduction
2.2 Physical process for an AB compound layer formation under non-irradiation process
2.3 Basic equations for an AB compound layer formation under non-irradiation process
2.4 Results and discussion on non-irradiation process
2.5 Conclusion
CHAPTER 3: INFLUENCE OF IRRADIATION ON AB COMPOUND LAYER FORMATION
3.1 Introduction
3.3 The influence of radiation- induced vacancies on the formation of an AB compound layer
3.3.1 Basic equations for an AB compound layer formation due to radiation-induced vacancy mechanism
3.3.2 Results and discussion on radiation- induced vacancy mechanism
3.4 The role of radiation- induced interstitial mechanism on the formation of an AB compound laye
3.4.1 Basic equations for an AB compound layer formation due to radiation- induced interstitial mechanism
3.4.2 Results and discussion on radiation- induced interstitial mechanism
3.5 Conclusion
CHAPTER4: SUMMARY, CONCLUSION, AND RECOMMENDATION
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