The main directions of researches in laboratory are:
Investigations in project Nr. 18.104.22.168/16/A/002 “High-resistivity resistive layer study” are carried out in colaboration with AS "ALFA RPAR”. The aim of the project is to carry out research and acquire knowledge about the possibilities of creating high-resistance resistive elements with reduced dimensions and high resistive values. The goal of the project is also to get knowledge about the methods, regimes and residual layers of metal silicide thin-layer coating methods.
Laser processing of amorphous hydrogenised silicon thin films for solar cell applications. Investigation of effects of pulsed laser processing on electric, structural, morphological and photoconductive properties of a-Si:H films. Development of hybrid and tandem solar cell prototypes.
The goals of EURATOM project are investigation and characterization of the impurity content in fusion plasmas and reactor hot wall. The objectives of this project require study of the influence of the liquid metal limiter on the main plasma parameters, including concentration of evaporated metal atoms in plasma. Laser spectroscopy techniques are proposed for development of procedures for research of impurities in plasma and plasma facing materials.
Materials for applications in optoelectronics.
Project “High-resistivity resistive layer study” is done in colaboration with AS “RPAR ALFA”. Reducing the size of the chips while increasing their working capacity is directly dependent on the small size precision resistive materials that can be created. The resistive materials are sputtered as an extremely thin layer (several hundreds of angstroms (10-10m)), producing a conductive layer and a resistive layer.
The aim of the project is to carry out research and acquire knowledge about the possibilities of creating high-resistance resistive elements with reduced dimensions and high resistive values. Upon reaching the knowledge of the development of high resistance (≥ 5kΩ) resistors with TCR ≤50ppm / C ° will create opportunities for the development of principally new products - analogue chips with integrated high-value resistors. The goal of the project is also to get knowledge about the methods, regimes and residual layers of metal silicide thin-layer coating methods. The acquired knowledge and the development of a new product based on it will help increase the range of products by offering customers a higher quality and precision analogue chips.
Laser processing of solar cell materials
Manufacturing of thin film amorphous silicon solar cells is perspective on condition of improving their efficiency and reducing production costs. Efficiency of amorphous silicon solar cells decreases with time due to formation of metastable light induced defects. Laser crystallization helps to cancel this effect. We apply visible laser wavelength for laser crystallization in contrast to widely used excimer laser crystallization, which able to process only ~100 nm thick a-silicon layer. Primary effects of laser crystallization of a-silicon are dopants activation, and increase of charge carrier mobility due to higher crystallinity of processed silicon. Additional effect is texturing of initially smooth surface, which decrease back reflection of incident light and increase solar cell efficiency.
Optical spectroscopy of fusion plasma and fusion reactor walls.
Within the framework of EURATOM project „Laser Ablation Spectroscopy for Impurity Depth Profiling and Concentration Imaging in Plasma”, the laser ablation spectroscopy method for rapid qualitative and quantitative surface analysis of the first wall material of thermonuclear fusion reactors has been developed.
The formation and composition of thin layers, as well as the condition of the near-surface layers of the plasma-facing components are the crucial factors for the exploitation of materials in thermonuclear fusion reactors. Deposition of carbon layers, tungsten and carbon migration, as well as retention and diffusion of hydrogen isotopes are the major concerns in fusion devices.
The specific objectives of the project include characterization of the impurity concentration, profiling and erosion in ITER-relevant materials using laser ablation spectroscopy. The activities comprise development of the methodology for impurity concentration analysis depth profile and erosion in the tokamak hot wall tiles as well as elaboration of the concept for emerging technologies for in situ express characterisation of impurity profiling and migration of ITER-relevant materials.
During implementation of project “High-resistivity resistive layer study” were carried out knowledge and technique about the possibilities of creating high-resistance resistive elements with reduced dimensions and high resistive values.
Research and Development of Silicon Thin Film Solar Cells
Manufacturing of amorhous silicon thin film solar cells can be very perspective if methods to improve soalr cell efficiency can be found. It is well known that efficiency of amorhous silicon solar cells decrease with time due to accumulation of methastable defects. It is possible to diminish this effect using laser crystalization procedure. Main positive effects of laser crystalization are dopant impurity activation and increase of charge carriers mobility. Commonly used excimer laser processing depth is only 100 nm, while thickness of amorhous silicon solar cell ranges from 500 to 1000 nm. We are using lasers of visible range, which allows to process simultaneously whole p-i-n structure of solar cell. It is worth to mention surface textiring after laser processing, which decrease light reflection and correspondingly increase solar cell efficiency.
Optical spectroscopy of fusion plasma and fusion reactor wall materials
In framework of EURATOM project Laser Ablation Spectroscopy for Impurity Depth Profiling and Concentration Imaging in Plasma we elaborated laser ablation spectroscopy method rapid qualitative and quantative characterization of fusion reactor wall material. The important problems of fusion reactor operation are carbon layer deposition, migration of wolfram and oxigen, and hydrogen isotope diffusion inside reactor wall materials. Two beam laser ablation spectroscopy allows to probe impurities concentration, distribution profile and characterize erosion of ITER wall materials.
- ALFA RPAR AS
J.Butikova, B.Polyakov, L.Dimitrocenko, E.Butanovs, I.Tale. Laser scribing on HOPG for graphene stamp printing on silicon wafer. Central European Journal of Physics. 11, 580, (2013).
B.Polyakov, L.Dorogin, S.Vlassov, M.Antsov, P.Kulis, I.Kink, R. Lohmus. In situ measurements of ultimate bending strength of CuO and ZnO nanowires. European Physical Journal B. 85, 366, (2012).
P.Kulis, J.Butikova, B.Polyakov, G.Marcins, J.Pervenecka, K.Pudzs, I.Tale. Work function of colloidal semiconducting nanocrystals measured by Kelvin probe, IOP Conf. Ser.: Materials Science and Engineering, 38, 012048, (2012).
B. Polyakov, S. Vlassov, L. Dorogin, P. Kulis, I. Kink, R. Lohmus: The effect of substrate roughness on the staticfriction of CuO nanowires, Surface Science. 606, 1393, (2012).
J.Butikova , G.Marcins, B.Polyakov, A.Muhins, A.Voitkans, I.Tale. Processing of amorphous Si by pulsed laser irradiation at different wavelengths, IOP Conf. Ser.: Materials Science and Engineering, 38, 012009, (2012).
G. Marcins, J. Butikova, I. Tale, B. Polyakov, R. Kalendarjov, A. Muhin: Crystallization processes of amorphous Si by thermal annealing and pulsed laser processing, IOP Conf. Ser.: Materials Science and Engineering 23, p.012035 (2011).
L. Dimitrocenko, P. Kulis, A. Sarakovskis, I. Tale, A. Voitkans: Dynamics of exciton creation and decay processes in composition- disordered InGaN thin films, IOP Conf. Ser.: Mater. Sci. Eng. 23, p. 012001 (2011).
L. Dimitrocenko, K. Kundzins, A. Mishev, I. Tale, A. Voitkans, P. Kulis: Growth temperauture influence on the GaN nanowires grown by MOVPE technigue, IOP Conf. Ser.: Mater. Sci. Eng. 23, p. 012026 (2011).
E. Elsts, U. Rogulis, J. Jansons, A. Sarakovskis, Cathodoluminescence of terbium and ytterbium activated oxyfluoride glasses and glass ceramics. Latvian Journal of Technical Sciences, 5, pp. 48 (2010)
I.Tale, L. Dimitrocenko, P. Kulis, G. Marcins, A. Sarakovskis, A. Voitkans, Localization dynamics of exciton luminescence in InxGa1-xN epitaxial films. 11th Europhysical Conference on Defects in Insulating Materials (EURODIM2010) IOPPublishing, IOP Conf. Series: Materials Science and Engineering, 15 012059 (2010)
J. Butikova, A. Sarakovskis, I. Tale: Laser-induced plasma spectroscopy plasma facing materials, 35th EPS Conference on Plasma Phys. Hersonissos, ECA Vol.32, P-2.011 (2008)
L.Dimitrocenko, J.Grube, P.Kulis, G.Marcins, B.Polyakov, A.Sarakovskis, M.Springis, I.Tale, AlGaN–InGaN–GaN Near Ultraviolet Light Emitting Diode, Latvian Journal of Physics and Technical Sciences, No.4, Vol. 45, p. 25, (2008)
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Jansons J. Fizikas profesoram Voldemāram Fricbergam (24.06.1926. – 02.08.1982.) – 90. – “Zvaigžņotā Debess” 2016. g. vasara (232), 31. – 37. lpp.
Jansons J. Fizikas profesors akadēmiķis Juris Ekmanis (2.XII 1941. – 9 IV 2016.). – “Zvaigžņotā Debess” 2016. g. vasara (232), 38. – 46. lpp.
I.Tāle., B.Poļakovs, J.Butikova, P.Kulis, G.Mārciņš, - “Amorfa Si slāņu lāzer-kristalizācijas paņēmiens mikro-Si un poli-Si saules šūnu iegūšanai” LV 14879 B.