INSTITUTE OF PHYSICS PUBLISHING SEMICONDUCTOR SCIENCE AND TECHNOLOGY Semicond. Sci. Technol. 19 (2004) 1057–1060 PII: S0268-1242(04)77399-X Synthesis and characterization of tin oxide microfibres electrospun from a simple precursor solution Yu Wang 1,3 , Milca Aponte 1 , Neliza Leon 1 , Idalia Ramos 1 , Rogerio Furlan 1 , Stephane Evoy 2 and Jorge J Santiago-Avil´ es 2 1 Department of Physics & Electronics, University of Puerto Rico at Humacao, CUH Station, Humacao 00791, Puerto Rico 2 Department of Electrical & Systems Engineering, University of Pennsylvania, 200 South 33rd Street, Philadelphia, PA 19104, USA Received 8 March 2004, in final form 13 May 2004 Published 7 July 2004 Online at stacks.iop.org/SST/19/1057 doi:10.1088/0268-1242/19/8/017 Abstract Tin oxide (SnO 2 ) microfibres in the rutile structure were synthesized using electrospinning and metallorganic decomposition techniques. Fibres were electrospun from a precursor solution containing 20 mg poly(ethylene oxide) (molecular weight 900 000), 2 ml chloroform and 1 ml dimethyldineodecanoate tin, and sintered in the air for 2 h at 400, 600 and 800 ◦ C, respectively. Scanning electron microscopy, x-ray diffraction and Raman microspectrometry were used to characterize the sintered fibres. The results showed that the synthesized fibres are composed of SnO 2 . (Some figures in this article are in colour only in the electronic version) 1. Introduction Tin oxide, SnO 2 , is a functional material with multiple interesting properties and important applications. As a semiconductor with a large bandgap (E g = 3.6 eV), it is transparent in the visible region of the spectrum, and has been used as conductive electrodes and anti-reflective coatings in solar cells and light emitting diodes (LEDs) [1–3]. Usually SnO 2 can be doped only as n-type. Cukrov et al [4] recently reported a weak p-type response in 5 mol%Fe 2 O 3 -doped SnO 2 . This promises a p-type SnO 2 semiconductor and wider applications such as the blue LED. More interestingly, the conductivity of SnO 2 semiconductor is modulated by the physisorbed oxygen molecules on its surface. The absorbed oxygen, receiving electrons from the conduction band, produces an electron depletion layer under the absorbing surface, and a potential barrier between particles, and thus decreases the conductivity of the SnO 2 [4–6]. This makes SnO 2 a good candidate for a gas sensor, whose conductivity will increase sharply when exposed to a reducing gas [4, 5]. 3 Present address: Department of Electrical and Computer Engineering, University of California, Davis, CA 95616, USA. Due to its high surface-to-volume ratio, SnO 2 film based gas sensors have been used widely to detect trace amount of gases such as carbon monoxide and ethanol. With a higher surface- to-volume ratio than thin films, fibres are expected to be more sensitive in these applications. This can be instrumental in the miniaturization of devices. In fact, one dimensional (1D) or quasi-1D structures have the lowest dimensionality for effective electron transport and photon excitations, and can be used as basic building blocks in the bottom-up assembly in diverse applications in electronics and photonics. However, while SnO 2 films have been synthesized using various methods, such as evaporation [7], reactive sputtering [8], spray pyrolysis [9], chemical vapour deposition (CVD) [1, 10] and sol-gel process [5, 11], only a few ways have been found to synthesize SnO 2 fibres. Liu et al [2] synthesized SnO 2 nanowires using laser ablation. Xu et al [6] prepared SnO 2 nanorods by thermal decomposition of SnC 2 O 4 precursor. Kolmakov et al [12] obtained SnO 2 nanowires by oxidizing electrodeposited metallic tin nanowires using a self-organized, highly ordered porous anodic alumina (PAO) template. Li et al [3] prepared Sb-doped SnO 2 nanofibres by electrospinning a solution containing poly(vinyl pyrrolidone) (binder), tin and antimony (III) alkoxides, acetic acid and organic solvents. 0268-1242/04/081057+04$30.00 © 2004 IOP Publishing Ltd Printed in the UK 1057