Influence of O2/Ar ratio on the properties of transparent conductive niobium-doped ZnO films

Abstract

et al. Influence of O 2 /Ar ratio on the properties of transparent conductive niobium-doped ZnO films.Niobium-doped ZnO transparent conductive films are deposited on glass substrates by radio frequency sputtering at 300℃. The influence of O 2 /Ar ratio on the structural, electrical and optical properties of the as-deposited films is investigated by X-ray diffraction, Hall measurement and optical transmission spectroscopy. The lowest resistivity of 4.0×10 −4 Ω·cm is obtained from the film deposited at the O 2 /Ar ratio of 1/12. The average optical transmittance of the films is over 90%.semiconductors, electrical properties, thin films, transparent conductive oxides, sputtering Transparent conductive oxide (TCO) thin films have been extensively studied for their practical applications, such as transparent electrodes, flat panel displays and solar cells [1] . Hitherto, different metal-oxide semiconductors such as In 2 O 3 , ZnO and SnO 2 have been employed to fabricate TCO thin films [2] . Among them, ZnO, a II-VI compound with hexagonal wurtzite crystal structure has attracted much focus owing to its distinctive optical, electronic and chemical properties [3][4][5][6][7][8] . Moreover, its low price and relatively low deposition temperature make it a good candidate for industrial applications. Several chemical and physical deposition techniques such as radio frequency (RF) sputtering, direct current (DC) sputtering, spray pyr7olysis, chemical-vapor deposition (CVD), pulsed laser ablation (PLA), sol-gel, reactive thermal evaporation and ion plating have been used to deposit ZnO TCO thin films [9] , and the film properties can be adjusted by controlling the doping materials and ratios [10] , deposition parameters [11] and post treatment [12] . Many scientific and technological efforts have been made in these fields, aiming at increasing the conductivity, transmission, stability and feasibility for practical use [13][14][15][16] . However, to the best of our knowledge, no report on the preparation of Nb-doped ZnO (NZO) thin films by RF sputtering has been explored [17] . On the other hand, as the TCO thin film properties strongly depend on the reaction between material source and oxygen [18] , exposing the dependence of film properties on O 2 /Ar ratio is useful in the future science.In the present work, highly transparent and conductive NZO thin films are deposited on glass substrates by RF sputtering at 300℃ with different O 2 /Ar ratios. The influence of O 2 /Ar ratio on the structural, electrical and optical properties of the NZO films is investigated and discussed.