A simple batch processing example

Silver layers on glass slides

To demonstrate the batch processing of a series of input spectra (realized in this case by an Excel macro controlling SCOUT_98 as OLE automation server) the set of reflectance spectra shown below of thin silver films deposited on microscope slides are investigated. The samples were prepared by sputtering with varying deposition time

The spectra were recorded by a Perkin-Elmer grating spectrometer in the range 9000 ... 50000 1/cm (200 ... 1100 nm wavelength) making use of an acquisition program also developed by our company. For deposition times less than 5 s an inhomogeneous island film grows, for larger times a compact layer develops building up the high metallic reflectivity in the visible spectral range (12000 ... 25000 1/cm).

To determine the sputtering rate the simple model of a homogeneous Ag film on glass has been used, taking literature data for silver from the optical constant database. Although the quality of the sputtered silver may differ from that used to obtain the literature data the individual simulations have a satisfying quality like the one shown above. Only the spectra of the island films are not reproduced well. This is no surprise since the optical properties of inhomogeneous metal films are very different from those of homogeneous ones.

The results for the Ag thickness (which has been the only fitting parameter) show a nice linear relation to the sputtering time from which the sputtering rate of roughly 1.3 nm/s is easily obtained.

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