Pyrometric interferometry has been performed in the formation of diamo
nd crystals and films synthesised on pretreated single silicon substra
tes by a microwave plasma assisted chemical vapour deposition (MPCVD)
technique. The growth mode of this material induces particular variati
ons of the emissivity ratio epsilon/epsilon(0) that we an able to simu
late theoretically, taking into account the nucleation mode (Volmer-We
ber), the nucleation density N and the growth rate nu of the diamond c
rystallites. The comparison between the experimental and the theoretic
al curves of the epsilon/epsilon(0) variations allows us to understand
better the first stage of the CVD diamond formation in terms of kinet
ic and nucleation density. Finally, the real-time monitoring of these
parameters is a very attractive objective for the precise control of t
he deposition process, for which the first stages are crucial for the
subsequent diamond film quality. (C) 1997 Elsevier Science S.A.