RESULTS AND DISCUSSION

3.1 LaserReflectometry

The reflectivity data at 532 nm were monitored as a function of time during the deposition of TiO2, SiO2and Al2O3 films on silicon substrates using the laser light polarization parallel to the incidence plane.

The obtained curves can be interpreted in a qualitative way. The experimental curves show oscillations with constant amplitude, indicating the transparency of the film. Hence, the extinction coefficient k at 532 nm is zero as expected. A quantitative determination of the optical constants is done by numerical fitting of the experimental data using the reflectivity formula of a one layer on substrate model. In a straightforward way, in-situ laser reflectometry fits provide the growth rate vd, the refractive and extinction indexes at one wavelength (532 nm) as summarized in table 1.

n

vd [nm/min]

TiO2

2.2

1.2

SiO2

1.47

7.6

A^O3

1.5

25

Table 1. Optical constants and deposition rate of TiO2, SiO2 and Al2O3 thin films using laser reflectometry.

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