Nitrogen – Doped SnO₂ Thin Films Prepared by Direct Current Magnetron Sputtering

Abstract:

Nitrogen - doped tin oxide (N-doped SnO₂) thin films were prepared on unheated glass substrate by dc magnetron sputtering of a Sn target in gas mixtures of O₂ and N₂. The N₂ flow rates were varied from 0 to 15 SCCM with the same working pressure of 1×10^-2 Torr. The as-deposited films were annealed in vacuum at 400 °C for 1 h. The films structure, electrical properties and optical properties were characterized by X-ray diffraction (XRD), 4-point probe and Hall effect measurement and portable fiber optic UV-vis spectrometer, respectively. The observed XRD patterns of films showed preferred (101) orientation of the SnO₂ tetragonal structure. The average crystalline size of the (101) diffraction peak decreased from 5.10 to 4.07 nm with N₂ flow rate increased. Hall measurement indicated that resistivity increased and carrier concentrations decreased as N₂ flow rate increased. The carrier concentrations decreased because N atoms substituted oxygen atom in SnO₂ lattice. The N atoms may forms acceptor level in SnO₂ band gap resulting in hole generation. The electron concentration from intrinsic defect were neutralized with the hole concentration. The carrier concentration decreased from 3.42×10¹⁷ cm^-3 for un-doped SnO₂ to the order of 10¹⁴ cm^-3. The average percent transmittance of un-doped SnO₂ of about 77.5% in visible range (400-700 nm) decreased to 60% with increasing N₂ flow rate. The optical band gap decreased from 3.64 eV for un-doped SnO₂ to 3.45 eV for N-doped SnO₂ films.

• Periodical: Advanced Materials Research (Volume 770)
• Pages: 169-172
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.770.169
• Online since: September 2013
• Authors: Prayoon Suapadkorn, Worawarong Rakreungdet, Tula Jutarosaga, Wattana Samanjit
• Keywords: DC Magnetron Sputtering, Hole Concentration, N-Doped SnO₂, Thin Film

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