Electrical and optical properties of gallium-doped zinc oxide films deposited by dc magnetron sputtering

Gallium-doped zinc oxide (GZO) films were deposited by dc planar magnetron sputtering using a GZO ceramic target. Deposition was carried out under various conditions of substrate temperature (RT-700 °C), residual water pressure (1.61 × 10 -4 -2.2 × 10 -3 Pa), and H 2 /(Ar + H 2 ) flow ratio (0-15%). A relatively low resistivity of 5 × 10 -4 Ω cm was obtained for films deposited at 400 °C, attributed to an increase in carrier density and Hall mobility. In the case of 100% Ar gas, the grain size and electrical properties of the GZO films deposited on RT substrates were heavily affected by residual water pressure in the deposition chamber. The resistivity increased from 3.0 × 10 -3 to 3.1 × 10 -2 Ω cm and the grain size of the films decreased from 24 to 3 nm when the residual water pressure was increased from 1.6 × 10 -4 to 2.2 × 10 -3 Pa. However, the introduction of H 2 to decrease the resistivity resulted in a decrease of grain size in proportion to H 2 flow ratio.