16. - 18. 10. 2013, Brno, Czech Republic, EU THE DEPOSITION OF AMORPHOUS AND AMORPHOUS HYDROGENATED SILICON WITH EMBEDDED CUBIC MG2SI NANOPARTICLES The-Ha STUCHLIKOVA 1 , Jiří STUCHLIK *1 , Zdenek REMES 1 , Radek FAJGAR 2 , Nikolay G. GALKIN 3 , Konstatntin N. GALKIN 3 , Igor M. CHERNEV 3 1 Institute of Physics ASCR, v. v. i., Prague, Czech Republic, EU 2 Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Prague, Czech Republic 3 Institute of Automation and Control Processes of FEB RAS, Vladivostok 5, Russian Federation * [email protected]ABSTRACT Our interest is focused on potential applications of Mg2Si for effective solar energy conversion in solar cells based on hydrogenated silicon thin films (Si:H). Si:H large scale diode structures are successfully deposited by Plasma Enhanced CVD technique (PECVD) but the reached efficiency of energy conversion for serious production is too low up to now. It is very well known that in the case of amorphous structure the absorption coefficient α is high but transport of charge in this structure is not adequate for higher efficiency. From opposite side the microcrystalline structure is more convenient for transport of charge but α is lower and that is why the solar cells have been thicker for sufficient absorption of light. That is why we study possibilities how to increase α by usage of magnesium silicide nanoparticles (Mg2Si-NPs) in structure of Si:H. In this paper we introduce two technics - combination of PECVD and Vacuum Evaporation (VE) and Reactive Laser Ablation (RLA) – for preparation of cubic structure of Mg2Si-NPs in amorphous (a-Si) or amorphous hydrogenated (a-Si:H) silicon matrix. Formation of Mg2Si-NPs was proved by Raman spectroscopy. Likewise we introduce optical changes measured at absorption edge and the first results on realized NIP structures. Keywords: Mg2Si nanoparticles, a-Si/a-Si:H matrix, RDA, PECVD, RLA 1. INTRODUCTION The Plasma Enhanced Chemical Vapour Deposition (PECVD) technique is widely used for deposition of large scale thin films on convenient surfaces and the technique is used for preparation of different structures. Final quality of the structures prepared is given by elements which are used and by compounds which we are able to create in plasma processes and finally by properties of final thin film structures or multi-structures. One of many examples of PECVD utilization is deposition of hydrogenated silicon (Si:H) thin films (usually in form of amorphous (a-Si:H) and microcrystalline (µc-Si:H) layers) for large scale solar cells [1]. But the PECVD technique is limited for preparation of thin layers from volatile precursors. Another method, the Reactive Deposition Epitaxy (RDE) is known as a technique for formation of silicides of different elements. The deposition technique is conducted under Ultra High Vacuum (UHV) conditions and the technique is used mainly in fundamental research for preparation of new materials. The technique allows to form silicide nanoparticles of different metals (Fe, Cr, Ca, Mg) possesing semiconducting properties and convenient band gap for advanced applications. For example magnesium silicide (Mg2Si) and magnesium silicide nanoparticles (/Mg2Si-NPs) possess a narrow band gap of 0.6 – 0.77 eV [2,3] and high absorption coefficient in the photon energy in range of 0.8-2.0 eV. But the research of this material is focused mainly on thermoelectric applications up to now. Due to optical properties of silicides, they are studied as dopants in the hydrogenated silicon thin film for effective solar energy conversion in solar cells. In this paper we demonstrate a deposition of Si:H diode structures by PECVD technique using silane (SiH4) as silicon precursor. But at room temperatures there is no volatile and convenient precursor for transport of magnesium into radiofrequency discharge. That is reason why we combined the PECVD and Vacuum
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16. - 18. 10. 2013, Brno, Czech Republic, EU
THE DEPOSITION OF AMORPHOUS AND AMORPHOUS HYDROGENATED SILICON WITH
EMBEDDED CUBIC MG2SI NANOPARTICLES
The-Ha STUCHLIKOVA1, Jiří STUCHLIK*1, Zdenek REMES1, Radek FAJGAR2,
Nikolay G. GALKIN3, Konstatntin N. GALKIN3, Igor M. CHERNEV3
1 Institute of Physics ASCR, v. v. i., Prague, Czech Republic, EU 2 Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Prague, Czech Republic
3 Institute of Automation and Control Processes of FEB RAS, Vladivostok 5, Russian Federation