The Influence of Dopants on the Growth of Diamond by CVD

Diamond is an important material in many industrial applications (e.g., machining of hard materials, bio-electronics, optics, electronics, etc.) because of its exceptional properties such as hardness, tolerance to aggressive environments, compatibility with human tissues, and high carrier mobility. However, a highly controlled method for growing artificial high-purity diamond on a range of different substrates is needed to exploit these exceptional properties. The Chemical Vapour Deposition (CVD) method is a useful tool for this purpose, but the process still needs to be developed further to achieve better control of growth. In this context, the introduction of dopant species into the gas phase has been shown to strongly influence growth rate and surface morphology. Density Functional Theory (DFT) methods are used to deepen our atomic-level understanding of the effect of dopants on the mechanism for CVD growth on diamond. More specifically, the effect of four dopants (N, P, B and S) has been studied on the important reaction steps in the growth mechanism of diamond. Substitution of N into the diamond lattice has generally been found to disfavour critical reaction steps in the growth of the 100-face in diamond. This negative effect has been related to electron transfer from the N dopant into an empty surface state, e.g., a surface carbon radical…


1. Introduction
1.1 Diamond
1.2 Chemical Vapour Deposition
1.2.1 General
1.2.2 Growth mechanism
1.3 Impurities
1.3.1 Nitrogen
1.3.2 Boron
1.3.3 Phosphorous
1.3.4 Sulphur
2. Computational methods and models
2.1 Ab initio approach
2.2 Density Functional Theory
2.3 Basis sets
2.4 Surface models for diamond
2.5 Electronic analysis
3. Results
3.1 Introduction
3.2 Effect of atomic nitrogen
3.2.1 Effect of a co-adsorbed NHx species on the diamond surface
3.2.2 Effect of substitutional N
3.2.3 Effect of a NH co-adsorbate next to a surface step
3.3 Effect of phosphorous, sulphur or boron atom
3.3.1 CH3 adsorption reaction
3.3.2 H abstraction reaction
4. Concluding remarks
4.1 Effect of atomic nitrogen
4.2 Effect of phosphorous, sulphur or boron atom
5. Future works
7. Acknowledgments
8. References

Author: Van Regemorter, Tanguy

Source: Uppsala University Library

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