Influence of oxygen and argon flow on properties of aluminum-doped zinc oxide thin films prepared by magnetron sputtering

摘要

In this study, the influence of the oxygen/argon (O_2/Ar) flow ratio on aluminum-doped zinc oxide (ZAO) films using a Zn_(1.22)Al_(0.02)O_(1.25) target was investigated systematically. Different samples were obtained by changing the O_2/Ar flow ratio from 0.11 to 3. The grain size first decreased and then increased as the O_2/Ar flow ratio increased, reaching a minimum size of 8.53 nm at a flow ratio of 1. All films showed different average transmit-tances above 400 nm because of different surface structures and film thicknesses; the thickness of films varied from 261 to 897 nm. Moreover, the ZAO films exhibited different optical bandgaps between 3.22 eV and 3.31 eV. The resistivity first increased from 2.1 × 10~(-4) Ωcm to 350 × 10~(-4) Ωcm and then decreased to 220 × 10~(-4) Ωcm with increasing O_2/Ar flow ratio. Both the carrier concentration and Hall mobility first decreased from 5.6 × 10~(20) cm~(-3) to 0.3 × 10~(20) cm~(-3) and from 3.9 cm~2/Vs to 0.6 cm~2/Vs, respectively, and then increased to 0.9 × 10~(20) cm~(-3) and 1.1 cm~2/Vs, respectively, with increasing O_2/Ar flow ratio.