Improvement of Optical and Electrical Properties of AZO Thin Films by Controlling Fluorine Concentration

Zinc oxide (ZnO) based transparent conducting oxides (TCO) thin films, are used in many applications such as solar cells, flat panel displays, and LEDs due to their wide bandgap nature and excellent electrical properties. In the present work, fluorine and aluminium-doped ZnO targets are prepared and thin films are deposited on soda-lime glass substrate using a RF magnetron sputtering unit. The aluminium concentration is fixed at 2 wt%, and the fluorine concentration is adjusted between 0 to 2.0 wt% with five different concentrations, namely, Al2ZnO98(AZO), F(0.5)AZO(97.5)(FAZO1), F(1)AZO(97)(FAZO2), F(1.5)AZO(96.5)(FAZO3), and F(2)AZO(96)(FAZO(4)). Thin films are deposited with an RF power of 40 W and working pressure of 5 m Ton - at 270 degrees C. The morphological analysis performed for the thin film reveals that surface roughness decreases in FAZO1 and FAZO2 samples when doped with a small amount of fluorine. Further, optical and electrical properties measured for FAZO1 sample show average optical transmissions of over 89 % in the visible region and 82.5 % in the infrared region, followed by low resistivity and sheet resistance of 3.59 x 10(-4) Omega cm and 5.52 Omega/sq, respectively. In future, these thin films with excellent optoelectronic properties can be used for thin-film solar cell and other optoelectronics applications.