Influence of sputtering power on the properties of thin layers of GZO for photovoltaic applications

In the present work, we have deposited gallium doped zinc oxide thin films by magnetron sputtering technique based nanocrystalline particles elaborated by sol–gel method. In the first step, the nanoparticles were synthesized by sol–gel method using supercritical drying in ethyl alcohol. The structural studied by X-ray diffractometry indicates that GZO has a polycrystalline hexagonal wurzite structure with a grain size of about 30 nm. Transmission electron microscopy measurements have shown that very small particles of GZO are present in the aerogel powder. Then, thin films were deposited onto glass substrates by rf-magnetron sputtering at ambient temperature. The influence of RF sputtering power on structural, morphological, electrical, and optical properties were investigated. It has been found that all of the films deposited were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The film deposited at 60 W showed the lowest electrical resistivity of 3.5 × 10⁻³ Ω cm achieved through the highest Hall mobility of 9.30 cm² V⁻¹ s⁻¹. All the GZO films in this study showed the optical transmittances higher than 80 %.