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Reactive Magnetron Sputtering Technique, Light Property And Porous Microstructure Of SnO2 Thin Films

Posted on:2017-03-30Degree:MasterType:Thesis
Country:ChinaCandidate:H Y YaoFull Text:PDF
GTID:2308330509452448Subject:Materials science
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SnO2 is a natural n type semiconductor with wide band gap. Its advantages include high carrier mobility of 250 cm2/V s, high transparency to visible light and exciton binding energy as high as 130 me V at room temperature, etc. Therefore, SnO2 thin films have broad applications such as transparent conductive thin films, gas sensors and photo-electrical devices, etc. Since the properties of SnO2 are affected mainly by its defect states and they can be revealed by optical characterization, so it has been attracted great attention; on the other hand, synthesis of nanostructured SnO2 thin films will exert vital influence on their optical properties. Therefore, study on SnO2 thin films in this thesis includes: firstly, SnO2 thin films were deposited by reactive magnetron sputtering(RMS). The effects of RMS parameters on the deposition of SnO2 films and their microstructure and optical properties were studied by scanning electron microscope(SEM) and discussed; secondly, the effects of annealing on the light absorption and photoluminescence(PL) properties of SnO2 films were investigated by using tube furnace and UV-vis spectrometer and PL set-ups.The mechanism of the PL was discussed; thirdly, as deposited SnO2 thin films were annealed in inert gas by rapid thermal processing(RTP) and special porous SnO2 thin films were formed. Its mechanism was proposed and testified.Results and conclusions are as follows:(1) the increasing of the sputtering pressure, O2 partial pressure and substrate temperature will decrease the deposition rate. SnO2 films deposited at high substrate temperature have large crystals and rough surfaces. The annealing process improves the crystallinity and changes the columnar structure into the condensed film;(2) the annealing process enlarges the optical band gap of SnO2 crystals to 3.85 eV and greatly enhances the PL intensity of the SnO2 film.The PL peak at about 610 nm is mainly resulting from the unoccupied electron states of the dangling bonds from nanocrystals at the surface of the SnO2 thin films;(3) A special porous SnO2 films were fabricated by RTP in Ar atmosphere. The formation mechanismof such porous SnO2 includes:(a) as deposited SnO2 thin films by RMS have low crystallinity;(b) as deposited SnO2 thin films are RTP treated in Ar atmosphere;(c)SnO2 thin films have micro-column structures and(d) the RTP temperature is higher than 1000 oC and the temperature elevation speed is higher than 100 oC/s. Moreover, the diameters of the holes in the porous films is in proportion to the thickness of the as–deposited SnO2 film. Therefore, diameters of the holes can be controlled by the thickness of the SnO2 thin film.
Keywords/Search Tags:SnO2, thin film, reactive magnetron sputtering, photoluminescence, rapid thermal processing
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