“…However, its electrical resistivity is still quite high because of their intrinsically low carrier density and mobility. One way to reduce electrical resistivity of SnO 2 films is to control the concentration of oxygen vacancy by doping an extrinsic dopant such as the elements in groups IIB, IIIB, VB, and VIIB of the Periodic Table. These elements can be, but not limited to, zinc [4,5], indium [6][7][8][9], gallium [10,11], aluminum [12][13][14][15], antimony [16][17][18], and fluorine [19][20][21][22]. Among them, fluorine-doped tin oxide (FTO) films show rather low resistivity (in the order of 10 À 4 Ω cm) and highly chemical-and thermal-stable [23].…”