Influence of ZnO buffer layer on the electrical, optical and surface properties of Ga-doped ZnO films

The influence of the ZnO buffer layer thickness on the structural, electrical, optical and surface properties of Ga-doped ZnO (GZO) films deposited on glass substrates by RF magnetron sputtering were investigated. X-ray diffraction results showed the obtained films had highly c-axis oriented with hexagonal (002) structures and GZO film with 20 nm buffer layer had the best crystalline quality. The resistivity in GZO/ZnO bi-layer films decreased significantly than that in GZO film without a ZnO buffer layer, and GZO film with 20 nm buffer layer showed the lowest resistivity of 4.09 × 10−4 Ω cm. The bi-layer films exhibited the highest transmittance of over 80% in the visible light range and displayed a low near infrared transmittance. The correlation between surface morphology and wettability was studied and GZO/ZnO bi-layer films exhibited hydrophobic property with contact angle of θ from 104° to 108.5°, indicating acceptable property of environmental durability.