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Publikācija: Nanocone Formation on P- and N-Type Silicon by Laser Radiation and Their Properties

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Nosaukums oriģinālvalodā Nanocone Formation on P- and N-Type Silicon by Laser Radiation and Their Properties
Pētniecības nozare 1. Dabaszinātnes
Pētniecības apakšnozare 1.3. Fizika un astronomija
Autori Gatis Mozoļevskis
Artūrs Medvids
Pāvels Onufrijevs
Igor Dmytruk
Irina Pundyk
Atslēgas vārdi Laser radiation, silicon, photoluminescence, nanocones
Anotācija Nowadays, nanostructures are one of the most investigated objects in semiconductor physics, especially due to Quantum confinement effect in quantum dots (0D), quantum wires (1D) and quantum wells (2D) [1]. A cone possesses the following unique properties: a small cone is a quantum dot – 0D and a long one is a quantum wire – 1D with the gradually decreasing diameter from the base till the top of the cone. Where radii of cone are equal or less than Bohr’ radius of electron, exciton or phonon Quantum confinement effect takes place. It is very challenging task to control doping in nanostructures. In this paper we show a new way to form nanocones and control P atoms doping in silicon by Nd:YAG laser irradiation.II. RESULTS AND DISCUSSION Nanocones were formed on n-Si (P) (111) with SiO2 layer and on p-Si (B) (100) with indium tin oxide layer. Samples were irradiated by pulse Nd:YAG laser with wavelength λ=532 nm and pulse duration 10 ns on X-Y scanning stage. Fig. 1. shows photoluminescence spectra of SiO2/n-Si structure. Photoluminescence intensity decreases by increasing intensity of laser irradiation. We propose that decrease of PL intensity is related to nanostructure doping with phosphorus [2]. Photoluminescence spectra of the ITO/p-Si structures with the maxima visible part of spectra obtained after laser irradiation at intensities of 1.13 MW/cm2 and 2.83 MW/cm2 are shown in Fig. 2. Position of the observed photoluminescence maximum compared with the bulk Si shows a significant “blue shift”. The maxima of the photoluminescence at visible part of spectra are explained by presence of the Quantum confinement effect in the top of nanocones. Fig.3 shows AFM image of nanocones formed by laser radiation.Nanocones formation mechanism is characterised by 2 stages: At the first stage generation and redistribution of intrinsic point defects and impurities in temperature gradient field takes place, which is caused by strongly absorbed laser radiation [3]. In the second stage formation of nanocones on the irradiated surface of a semiconductor due to mechanical plastic deformation of the top layer enriched by interstitials and relaxation of the mechanical compressive stress arising between top layer and buried layer enriched by vacancies takes place III. CONCLUSIONS 1. Photoluminescence intensity decreases by increasing intensity of the laser irradiation. It can be explained by nanostructure doping of phosphorous. 2. ”Blue shift” of PL spectra in p-Si (B) we explain by Quantum confinement effect in nanocones IV. REFERENCES [1] G. Cao: Nanostructures & Nanomaterials, Imperial College Press, London, (2004), p. 448. [2] Pavesi, R. Turan: Silicon Nanocrystals, Wiley-VCH, Weinheim, (2010) p. 652. [3] Medvid A: Redistribution of Point Defects in the Crystalline Lattice of a Semiconductor in an Inhomogeneous Temperature Field, Defect and Diffusion Forum , 2002, 210-212: 89-102.
Hipersaite: http://scientific-conference2012.rtu.lv/sites/default/files/RTU_Conference_2012.pdf 
Atsauce Mozoļevskis, G., Medvids, A., Onufrijevs, P., Dmytruk, I., Pundyk, I. Nanocone Formation on P- and N-Type Silicon by Laser Radiation and Their Properties. No: Riga Technical University 53rd International Scientific Conference: Dedicated to the 150th Anniversary and the 1st Congress of World Engineers and Riga Polytechnical Institute / RTU Alumni: Digest, Latvija, Riga, 11.-12. oktobris, 2012. Riga: RTU, 2012, 203.-203.lpp. ISBN 978-9934-10-360-5.
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