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6195900 
Book/Book Chapter 
3.10 - Ultrafast Deposition of Diamond by Plasma-Enhanced CVD 
Achard, J; Brinza, O; Derkaoui, N; Gicquel, A; Hassouni, K; Lombardi, G; Michau, A; Rond, C; Silva, F; Tallaire, A; Wartel, M 
2014 
Elsevier 
Oxford 
Comprehensive Hard Materials 
217-268 
The answer to the question "how can we deposit diamond of very high purity/high quality at ultrahigh growth rate by chemical vapor deposition" can be expressed in very simple words: just produce as much as possible hydrogen atoms in a very clean system, and prevent their loss until they get to the growing surface! To that, we will add "manage" carefully hydrocarbon injection into the reactor. This chapter is dedicated to the understanding of how a 2.45GHz microwave (MW) cavity-based diamond deposition reactor working under moderate pressure and high power density in H2-CH4 mixtures operates. The focus is to identify how and where the key species for growing diamond, H atoms and CH3 radicals, are formed and lost into the plasma and at the plasma/surface interface until they reach the diamond surface where they are consumed by surface reactions, including diamond growth. The study is based on plasma modeling and spectroscopic analysis means. It is shown that one of the best ways to increase these species densities at the surface and grow ultrafast diamond is to couple as much as possible MW power, increasing simultaneously the pressure and the power in order to raise the gas temperature and to reduce the boundary layer thicknesses on the diamond surface. However, limitations appear at high power density in terms of thermal management, filamentation of the discharge, and methane addition due to soot formation that prohibits long-time deposition. Other effects are studied such as using pulsed plasmas, adding argon, changing the cavity, and/or its excitation frequency. Comparison is made with the results obtained in fully dissociated plasma flowing at high speed. 
Argon addition; Boundary layer thicknesses 
Sarin, Vinod K.