Growth and electro-optical properties of Ga-doped ZnO films prepared by aerosol assisted chemical vapour deposition

Transparent conductive Ga-doped ZnO thin films were deposited onto glass substrates by a low-cost aerosol assisted chemical vapour deposition technique and the effect of gallium content on the ZnO film growth behaviour and opto-electronic properties was systematically investigated. It is found that, upon increasing Ga addition, the ZnO film crystallinity exhibits a continuous reduction in quality associated with the preferential orientation transformed from (002) to (102). The (002) oriented samples had a microstructure of parallel columnar grains while the (102) oriented coating was thickened by overlapping particles. The ZnO:Ga coatings exhibit high carrier concentration (up to 4.1 × 1020 cm- 3) but low carrier mobility (up to 0.8 cm2 V- 1 s- 1), resulting in a minimum resistivity value of 2.3 × 10- 2 ? cm. The inferior carrier mobility performance could result from a profound ionized and neutral impurity scattering effect. Good visible transmittance (? 70-80%) is observed in these ZnO:Ga films and samples with higher carrier density present better infrared reflection performance (up to 37.2% at 2500 nm).