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Abstract. Establishing the optimal experimental conditions for the development of transparent metal contacts to be used in optoelectronic devices, such as organic light-emitting diodes and solar cells, is an important task. In this paper we present an overview of the development of very thin e-beam-deposited chromium films with high optical transparency. The surface morphology is investigated by scanning electron microscopy. The variation is examined of the films' electrical and optical properties (transmittance and complex refractive index) with the variation of the thickness and deposition rate. We observed that, for a given thickness of the chromium films, the absorption coefficient increases when the deposition rate is decreased. We also found that the thin films with a thickness of less than 10 nm show an average transmittance exceeding 60 % in the spectral range 400 -1500 nm. The films' resistivity, ρ, is determined by the four-point probe method. The value of ρ varies in the range of 10 -3 − 10 −4 Ω cm for chromium coatings in the thickness interval 5 − 100 nm. The results obtained show that very thin metal films could be an alternative to the transparent conductive oxides. IntroductionThin chromium films have found many applications, for example as layers for improvement of the adhesion to transparent substrates [1], in mask production [2] and as transparent electrodes [3]. Recently, it has been demonstrated that the ultrathin transparent metal contacts provide a number of advantages over the more commonly used conductive transparent metal oxides, such as indium tin oxide (ITO) [4]. According to [5], chromium and nickel thin films possess optical transparency comparable to that of the ITO in the visible and near-infrared range (0.4 − 2.5 μm), while it can be significantly higher in the ultraviolet (175 − 400 nm) and mid-infrared (2.5 − 25 μm) regions.The conditions of deposition, as deposition rate, temperature of substrate, etc., influence very strongly the properties of the metal coating [6]. It has been shown that the deposition rate and argon partial pressure in the case of cathode sputtering strongly affect the microstructure and electrical properties of thin chromium films [7,8]. Metal films deposited by ion-beam sputtering display exceptionally low surface roughness, the films being as thin as about 20 Å [3].The goal of the present work is the investigation of the optical and electrical properties of very thin chromium films deposited by an electron-beam technique.

A review is given on the application of the reflectance ellipsometry for optical characterization of bulk materials and thin films with thickness betweenλ/20 and 2λ(atλ=632.8 nm). The knowledge of the optical constants (refractive index,n, and extinction coefficient,k) of thin films is of a great importance from the point of view of modelling and controlling the manufacture of various optical elements, such as waveguides, diffraction gratings, and microlenses. The presented results concern the optical properties of thin films from multicomponent chalcogenide glasses on the base of As2S3and GeS2determined by multiple-angle-of-incidence ellipsometry and regarded as a function of the composition and thickness. The homogeneity of the films is verified by applying single-angle calculations at different angles. Due to decomposition of the bulk glass during thermal evaporation, an optical inhomogeneity of the thin As (Ge)-S-Bi(Tl) films is observed. The profile ofnin depth of thin As-S-Tl (Bi) films was investigated by evaporation of discrete layers. It is demonstrated that homogenous layers from the previous compounds with controlled composition can be deposited by coevaporation of As2S3and metals or their compounds (Bi, Tl, In2S3).