Electron transport and optical characteristics in amorphous indium zinc oxide films

This paper discusses the electron transport and the optical characteristics of amorphous indium zinc oxide and the role of the oxygen partial pressure on tailoring its properties. The data show that by varying the oxygen partial pressure during the deposition process from 10−3 to 2 × 10−1 Pa, the electrical resistivity varies from about 10−4 to 2 × 101 Ω cm, which corresponds to a variation on the Hall mobility from 60 to 10 cm2 V−1 s−1. The conductivity and mobility analysis show that the transport of carriers is not band tail limited, as happens in conventional disordered semiconductors, but highly dependent on the ionicity and the presence of oxygen vacancies, where mobility is mainly limited by carrier scattering. The optical characteristics inferred from the transmittance data reveal films with optical gaps in the range of 3.68–3.76 eV, very close to the ones observed on crystalline/polycrystalline IZO films (3.7–3.9 eV).