UV-VIS Photoconductivity of Nanocrystalline Tin Oxide
Tin dioxide with crystallite size 4–22 nm and specific surface area 10–110 m2/g have been prepared by conventional hydrolysis of tin(IV) chloride. The prepared gel was dried and then annealed at different temperatures varied from 300 to 700 °C in order to form nanocrystals. Structural properties of the samples were investigated by using X-ray diffraction, transmission electron microscopy, thermoprogrammable hydrogen reduction and low temperature nitrogen adsorption method. Photoconductivity of nanocrystalline SnO2 was studied under UV (λmax = 380 nm) and green light (λmax = 535 nm) illumination. The influence of SnO2 annealing temperature on photoconductivity behavior under UV and green light demonstrates opposite trends. The maximum response to UV radiation is observed for SnO2 annealed at 300 °C and it decreases with increasing annealing temperature of the samples. Under green light illumination the maximum conductivity growth was found for SnO2, annealed at 700 °C. The dominant mechanism for the conductivity increase under UV illumination is the photodesorption of oxygen. The lowering of photoresponse correlates with the decrease of specific surface area of the samples and low temperature hydrogen consumption in TPR-H2 experiments. The photoconductivity of tin oxide under green light illumination can be explained by the presence of deep acceptor levels in SnO2 band gap related to surface oxygen vacancies. According to electron paramagnetic resonance investigation the high temperature annealing results in the generation of oxygen vacancies, which may be responsible for high photoresponse of SnO2 annealed at 500 and 700 °C under green light illumination.
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Document Type: Research Article
Publication date: November 1, 2012
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- Journal of Nanoelectronics and Optoelectronics (JNO) is an international and cross-disciplinary peer reviewed journal to consolidate emerging experimental and theoretical research activities in the areas of nanoscale electronic and optoelectronic materials and devices into a single and unique reference source. JNO aims to facilitate the dissemination of interdisciplinary research results in the inter-related and converging fields of nanoelectronics and optoelectronics.
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