High conductivity and transparent ZnO:Al films prepared at low temperature by DC and MF magnetron sputtering

Aluminum-doped zinc oxide thin films have been deposited by DC and MF magnetron sputtering from a ceramic oxide target in argon atmosphere without direct heating of the substrates. The samples were prepared at different predetermined conditions of input power or discharge voltage and the influence upon electronic, optical, and microstructural properties has been investigated. The as-deposited layers show low resistivity, such as 9 × 10− 4 Ω cm minimum for DC excitation and 1.2 × 10− 3 Ω cm for MF mode, with growth rates up to 130 nm/min, and resulting substrate temperatures always below 200 °C. Low resistivity of the films is combined with high transmission, 85–90% in the visible wavelength range (400–800 nm). A strong (002) texture perpendicular to the substrate has been found, with lower strain for DC than for MF sputtering.