General Mobility and Carrier Concentration Relationship in Transparent Amorphous Indium Zinc Oxide Films

We report the dependence of the electronic properties on the metal composition and oxygen content of transparent conducting amorphous indium zinc oxide (a-IZO) films deposited by dc magnetron sputtering. a-IZO shows a clear Burstein-Moss shift with an effective optical band gap of 3.1 eV independent of the metal composition. A metal-composition-independent dependence of the mobility (μ) on carrier concentration (N) is also found for a-IZO with μmax =54 cm2 V s at N=1.3× 1020 cm-3. The electron transport, thermally activated at N≤ 1019 cm-3, becomes limited by lattice scattering at N ≈ 1020 cm-3 and then by ionized impurity scattering at N>5× 1020 cm-3.