Electrical and optical properties of gallium-doped zinc oxide thin films prepared by Ion-Beam-Assisted Deposition

Gallium doped zinc oxide films were prepared by Ion-Beam-Assisted Deposition. The effects of argon and oxygen bombardment flux on electrical and optical properties were studied according to the existence of excited species. The prepared films were polycrystalline in nature with c-axis perpendicular to the substrate. The resistivity of the film decreased to 1.35 × 10^-3 Ω-cm, and the optical transparency increased up to 80%, as the discharge current in ion gun was increased. The variation of discharge current mostly affected the grain size and crystallinity, which in turn affected the carrier mobility. Too much argon bombardment may disrupt grain growth, which resulted in higher resistivity. An optical emission spectrometer (OES) was used to examine the optical emission spectra of the ion beam, mainly for the excited oxygen and argon species. It was found the O∗/Ar∗ratio peaked with the increase of discharge current set in ion gun, then, decreased. This trend was similar to that of the electrical properties.