Jae Yoon Baik

High-resolution soft x-ray spectroscopic study on amorphous gallium indium zinc oxide thin films

Amorphous gallium indium zinc oxide (a-GIZO) thin films of different compositions (Ga2O3:In2O3:ZnO=1:1:1,2:2:1,3:2:1,4:2:1) on Si substrates were investigated by high-resolution x-ray photoelectron spectroscopy and x-ray absorption spectroscopy (XAS) using synchrotron radiation. The O 1s, Ga 3d, In 4d, Zn 3d core, and shallow-core levels as well as the valence band maxima and O K-edge XAS were investigated. Each O 1s spectrum could be deconvoluted by a main component (O1 in the text) representing the Ga–In–Zn–O quaternary system along with two other higher-binding energy (BE) components (O2 and O3 in the text). The O2+O3 intensity increased as the Ga2O3 content increased. For the as-prepared samples, the spectral peak separations between the Ga 3d (∼20 eV) and Zn 3d (∼11 eV) orbitals and between the In 4d (∼18 eV) and Zn 3d orbitals became larger, respectively, as the Ga2O3 content increased. For the surface-cleaned samples, this trend was the same but with smaller increases in their separations. The sput...

Sputtering Effect on Amorphous Ga-In-Zn-O Thin-Film Surface: Occurrence of Subgap and Metallic States

The chemical states of Ne+-ion-sputtered amorphous Ga-In-Zn-O (a-GIZO) thin films were investigated by high-resolution X-ray photoelectron spectroscopy. The sputtering reduced the Zn and In contents relative to that of Ga and generated a subgap state above the valence band maximum. Further sputtering resulted in metallic states at the In3d and In4d orbitals and at the Fermi energy edge, more so for the lower Zn- and In-content film. Locally generated metallic In is suggested to contribute to the metallic states.

Effect of Oxygen/Argon Flow Ratio on the Optical Properties of RF Sputtered a‐GaInZnO Thin Film

Transparent oxide semiconductor, a‐GaInZnO, thin films were deposited by radio frequency (RF) magnetron sputtering at different oxygen/Argon (O2/Ar) flow ratio on glass substrates. The effect of oxygen content was studied on the transmittance and optical band gap of these thin films. The average transmittance in the visible region decreased with increase in the oxygen content. The optical band gap also decreased with increase in the oxygen content. With increasing oxygen content, the absorption edge shifted to the longer wavelength due to the decreased Burstein‐Moss effect.

Ne{sup +} ion sputtering effect on amorphous Ga-In-Zn-O thin-film surface investigated by high-resolution XPS

The effect of Ne{sup +} ion sputtering on amorphous Ga-In-Zn-O (a-GIZO) thin films was investigated by using surface-sensitive, synchrotron-radiation-based, high-resolution X-ray photoelectron spectroscopy (XPS). a-GIZO thin films having different compositions (Ga{sub 2}O{sub 3}:In{sub 2}O{sub 3}:ZnO = 1:1:1, 2:2:1, 3:2:1, 4:2:1) were investigated. It was found out that the amounts of the In and Zn contents relative to that of Ga decreased noticeably after sufficient sputtering, and that there occurred a subgap state above the valence band maximum and metallic states at the In 3d and 4d core levels as well as at the Fermi edge.