We report the dependence of the electronic properties on the metal composition and oxygen content of transparent conducting amorphous indium zinc oxide $\left(a\text{−}\mathrm{IZO}\right)$ films deposited by dc magnetron sputtering. $a\text{−}\mathrm{IZO}$ shows a clear Burstein–Moss shift with an effective optical band gap of $3.1\mathrm{eV}$ independent of the metal composition. A metal-composition-independent dependence of the mobility $\left(\mu \right)$ on carrier concentration $\left(N\right)$ is also found for $a\text{−}\mathrm{IZO}$ with ${\mu }_{\max }=54{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ at $N=1.3\times {10}^{20}{\mathrm{cm}}^{-3}$. The electron transport, thermally activated at $N⩽{10}^{19}{\mathrm{cm}}^{-3}$, becomes limited by lattice scattering at $N\approx {10}^{20}{\mathrm{cm}}^{-3}$ and then by ionized impurity scattering at $N>5\times {10}^{20}{\mathrm{cm}}^{-3}$.

• Received 24 December 2007

DOI:https://doi.org/10.1103/PhysRevB.77.115215