Ga‐doped zinc oxide: An attractive potential substitute for ITO, large‐area coating, and control of electrical and optical properties on glass and polymer substrates

— Ga-doped ZnO (GZO) films with thicknesses of 30–560 nm were prepared on glass substrates at 200°C by ion plating with direct-current arc discharge. The dependences of the characteristics of GZO films on thickness were investigated. All the polycrystalline GZO films, which showed high transmittance in the visible region, were ZnO crystallites with a wurtzite structure highly oriented along the (0002) plane. The resistivity, ρ, of GZO films decreases with increasing film thickness. The highest ρ achieved is 4.4 × 10−4 Ω-cm with a carrier concentration, n, of 7.6 × 1020 cm−3 and a Hall mobility, μ, of 18.5 cm2/V-sec, determined by Hall effect measurement for the GZO films with a thickness of 30 nm, and the lowest ρ is 1.8 × 10−4 Ω-cm with n = 1.1 × 1021 cm−3 and μ = 31.7 m2/V-sec for the GZO film with a thickness of 560 nm. In addition, highly transparent GZO films with thicknesses of 12–300 nm were fabricated on unheated polymethyl methacrylate (PMMA). The ρ of these transparent GZO films decreased from 20 to 4 × 10−4 Ω-cm with film thickness.