Optical Characterization of AsTe Films Grown by Plasma Deposition Based on the Advanced Optimizing Envelope Method.

Three AsTe films with different x and dissimilar average thickness are characterized mainly from one interference transmittance spectrum ( = 300 to 3000 nm) of such film on a substrate based on the advanced optimizing envelope method (AOEM). A simple dual transformation of () is proposed and used for increasing the accuracy of computation of its envelopes () and () accounting for the significant glass substrate absorption especially for > 2500 nm. The refractive index () of AsTe and AsTe films is determined with a relative error <0.30%. As far as we know, the AsTe film is the only one with anomalous dispersion and the thickest, with estimated = 1.1446 nm, ever characterized by an envelope method. It is also shown and explained why the extinction coefficient () of any of the three AsTe films is computed more accurately from the quantity () = [()()] compared to its commonly employed computation from (). The obtained results strengthen our conviction that the AOEM has a capacity for providing most accurate optical characterization of almost every dielectric or semiconductor film with > 300 nm on a substrate, compared to all the other methods for characterization of such films only from ().