Untitled

Abstract

In this paper, we carry out in situ optical characterization of diamond films on silicon substrates using an infrared bichromatic pyrometer under oblique incidence. We develop an optical model taking into account the effective emissivity of the diamond film/silicon substrate system. This model allows the determination of the diamond and silicon optical constants, the system real temperature, the incubation period and the growth rate, from the apparent temperature measured during the diamond growth. These parameters are found from the experimental data and from minimizing the mean square error using the Levenberg-Marquardt algorithm. The model can be extended to other partially transparent deposits on absorbent substrates at any observation angle and the first-hand values of the film optical constants can be found without the knowledge of the substrate optical properties. The pyrometric results thus obtained on the diamond films deposited by microwave plasma-assisted chemical vapour deposition in a CH4-H2 gas mixture are discussed and compared to those deduced from Raman spectroscopy in order to investigate the diamond purity. As the CH4 concentration is augmented, the decrease in the diamond purity thus found is in agreement with the increase in the film extinction coefficient evaluated from pyrometry. Moreover, the behaviour of the apparent temperature pseudo-period provides information on the growth process with respect to the growth rate and the film real index variations.

Effect of argon addition on the growth of thick single crystal diamond by high‐power plasma CVD

“…The growth rates were evaluated using two different methods. The first one relies on the measurement of interference fringes observed using a laser interferometer operating at λ = 633 nm as expressed below 14: where R is the growth rate, N is the number of fringes observed, t dep is the deposition time, n dia is diamond's refractive index ( n dia = 2.4) and θ is the angle between the incident laser beam and the substrate normal. The second method is based on the weight increase before and after deposition.…”

Early Periods of Low-Temperature Linear Antenna CVD Nucleation and Growth Study of Nanocrystalline Diamond Films

“…However, there is very little literature available in which growth has been reported at a temperature of less than 300 • C [17,18]. Reporting of the respective substrate temperature during CVD has mostly been carried out in situ, using optical pyrometers [19], but low LA-MPCVD processing temperatures do not allow the use of such optical instruments [15]. Therefore, thermocouples and infrared thermometers are placed underneath the substrate stage to reliably record the LA-MPCVD growth temperatures, where it is protected or uninfluenced from the effect of CVD plasma in the diamond growth environment.…”

Early Periods of Low-Temperature Linear Antenna Cvd Nucleation and Growth Study of Nanocrystalline Diamond Films

“…However, there is very little literature available where growth has been reported at less than 300oC temperature [17,18]. Reporting of the respective substrate temperature during CVD has mostly been done in situ, by optical pyrometers [19], but low LA-MPCVD processing temperatures do not allow to use of such optical instruments [15]. Therefore, thermocouples and infrared thermometers are placed underneath the substrate stage to record reliably the LA-MPCVD growth temperatures, where it is protected or uninfluenced from the effect of CVD plasma in the diamond growth environment.…”