We report results from a plasma source; a diffuse coplanar surface discharge (DCSD), which is capable of generating macroscopically uniform thin layers of diffuse plasmas in air and other reactive gases at atmospheric pressure. DCSD is a type of dielectric barrier discharge generated on the surface of a dielectric barrier with embedded electrodes, which appears to be advantageous to surface treatment and deposition processes. Preliminary results on hydrophilization of polypropylene nonwoven fabric are also presented.
Evaluation of photoluminescence spectra of porous silicon (PS) samples prepared by electrochemical etching is presented. The samples were measured at temperatures 30, 70 and 150 K. Peak parameters (energy, intensity and width) were calculated. The PL spectrum was approximated by a set of Gaussian peaks. Their parameters were fixed using fitting a procedure in which the optimal number of peeks included into the model was estimated using the residuum of the approximation. The weak thermal dependence of the spectra indicates the strong influence of active defects.K e y w o r d s: porous silicon, photoluminescence pectrum, Gaussian peaks, spectra evaluation
Output beam spatial properties of a dual wavelength CW DPSS laser have been studied using the thermal lens (photothermal) effect. In employing the Z-scan technique both the steady-state and time-dependent thermal lens signal as a function of sample position could be examined simultaneously. The influence of sample thickness and laser output power upon obtained spatial properties of incident beam is studied. It is shown, that both the steady state and the transient photothermal signal provide comparable results.
Abstract:The paper deals with the complex refractive index and photoluminescence in the IR-VIS light region of two sample types (i) black p-type silicon (BSi) produced by the surface structure chemical transfer method using Pt catalytic mesh, and (ii) porous p-type silicon prepared by standard electrochemical etching. We present, compare, and discuss the values of the IR-VIS complex refractive index obtained by calculation using the Kramers-Kronig transformation and the photoluminescence properties thereof. The results indicate that differences between the optical properties of the BSi and the porous Si are given by (a) the oxidation procedure of BSi, (b) the thickness of the formed black and porous Si layer, and by (c) the porosity of both layer types. We assume that the photoluminescence signal generated by oxidized BSi structures can be mainly related to the quantum confinement effect, while the photoluminescence of the porous p-type Si is caused by the optical activity of the SiO x H y compounds covering its surface region.
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