Optical Characterization of As(x)Te(100−x) Films Grown by Plasma Deposition Based on the Advanced Optimizing Envelope Method

Three As(x)Te(100)(−)(x) films with different x and dissimilar average thickness [Formula: see text] are characterized mainly from one interference transmittance spectrum T(λ = 300 to 3000 nm) of such film on a substrate based on the advanced optimizing envelope method (AOEM). A simple dual transformation of T(λ) is proposed and used for increasing the accuracy of computation of its envelopes T(+)(λ) and T(−)(λ) accounting for the significant glass substrate absorption especially for λ > 2500 nm. The refractive index n(λ) of As(40)Te(60) and As(98)Te(2) films is determined with a relative error <0.30%. As far as we know, the As(80)Te(20) film is the only one with anomalous dispersion and the thickest, with estimated [Formula: see text] = 1.1446 nm, ever characterized by an envelope method. It is also shown and explained why the extinction coefficient k(λ) of any of the three As(x)Te(100)(−)(x) films is computed more accurately from the quantity T(i)(λ) = [T(+)(λ)T(−)(λ)](0.5) compared to its commonly employed computation from T(+)(λ). 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 [Formula: see text] > 300 nm on a substrate, compared to all the other methods for characterization of such films only from T(λ).