Structure and properties of Al-doped ZnO transparent conductive thin-films prepared by asymmetric bipolar pulsed DC reactive magnetron sputtering.

Transparent conductive thin-films of aluminum-doped zinc oxide (AZO) were deposited on STN-glass substrates by an asymmetric bipolar pulsed DC (ABPDC) reactive magnetron sputtering system. Two different alloys, Zn-1.6 wt% Al and Zn-3.0 wt% Al, were used as the sputtering targets. The films consist of columnar grains with a preferred orientation of c-axis. Strong crystal distortion and high density stacking faults were observed in high resolution TEM micrographs. The full-width at half-maximum (FWHM) of the (002) rocking curve has a close relationship with the resistivity of the films; the smaller the FWHM, the lower the resistivity. The lowest resistivity of 7.0 x 10(-4) omega-cm was obtained from the film deposited with Zn-1.6 wt% Al target at 200 degrees C.