Papers by Author: J. Olejníček

Abstract: Pulse modulated double hollow cathode RF plasma jet system with two separate independent nozzles made of BaTiO3 (BTO) and SrTiO3 (STO) was used for deposition of BSTO thin films on Si and on multi-layer Si/SiO2/TiO2/Pt substrates. Dielectric properties of BSTO layers strongly depend on ratio composition expressed by parameter x = Ba/(Ba+Sr) and on accuracy in presence of other elements. Space resolved optical emission spectroscopy (OES) was used mainly for monitoring of concentration of particles sputtered from the hollow cathode and for feedback correction of power supplied in both nozzles because applied power was responsible for sputtering speed of Ba and Sr particles. Main attention was focused on relation between ratio of spectral intensity of Ba, Ba+, Sr and Sr+ lines close to substrate and ratio of Ba and Sr concentration in the deposited film. 2D map of emission lines intensity distribution for Ba, Ba+, Sr, Sr+, Ti, Ar, and Ar+ for double hollow cathode plasma jet system with BTO and STO nozzles was created. OES was also used for observing of excess of Ti particles in final layer with negative effect on layer properties and for measurement of rotational temperature of OH radicals. Preliminary results of all these optical measurements are published in this paper. Deposited thin films were analyzed by X-ray diffraction, which confirmed presence of BSTO and STO perovskite phase in the films, by atomic force microscopy (AFM), by electron microprobe and by micro-Raman scattering measurement.

Abstract: Thin films of CuIn1-xBxSe2 (CIBS) as absorption layer in single-junction solar cells can potentially grant a higher band gap in comparison with other studied chalcopyrite materials like CuIn1-xGaxSe2 (CIGS) and CuIn1-xAlxSe2 (CIAS). The higher band gap near optimum value ~ 1.4 eV can help to achieve higher efficiency (today 19.5% for CuIn0.74Ga0.26Se2). In this paper are described first results of experiments with effort to produce CIBS films by selenization of CuInB precursor alloy in Se vapors. Resulting material was analyzed by Raman spectroscopy, X-ray diffraction, and Auger electron spectroscopy. Measurements show that formation of CIBS layer is complicated by forming of pure CuInSe2 layer with unwanted Cu2-xSe phases and by accumulation boron near to the substrate.

Abstract: Technology aspects and characterization of BaxSr1-xTiO3 (BST) films fabricated with low pressure plasma jet technique are presented. BST films were deposited on silicon coated with Pt/TiO2/SiO2 and on bare Si substrates. The nozzles-type RF hollow cathode has been fabricated from hot pressed BaTiO3, SrTiO3, and BST ceramics. Controlling of RF voltage, RF current and substrate temperature allowed us to deposit reproducible films with controlled grain size. Hysteresis loops, ellipsometric and micro-Raman investigation results are presented and discussed.