Blue shift in the optical band gap of amorphous Hf–In–Zn–O thin films deposited by RF sputtering

• Published in: Journal of alloys and compounds 2012-06, Vol.525, p.172-174
• Main Authors: Thakur, Anup, Kang, Se-Jun, Baik, Jae Yoon, Yoo, Hanbyeol, Lee, Ik-Jae, Lee, Han-Koo, Jung, Seonghoon, Park, Jaehun, Shin, Hyun-Joon
• Format: Article
• Language: English
• Subjects: Amorphous Hf–In–Zn–O; Amorphous semiconductors; glasses; Blue shift; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Optical band gap; Optical properties; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2012.02.091

[Display omitted] ► Optical band gap enhanced by 13% as O2/Ar flow ratio increased. ► a-HIZO films deposited at higher O2/Ar flow ratio were more resistive. ► Oxygen incorporation at higher O2/Ar flow ratio may explain the band gap increase. ► Reduction of oxygen vacancies at higher O2/Ar flow ratio may explain the resistivity increase. Amorphous Hf–In–Zn–O (a-HIZO) thin films were grown by radio frequency (RF) magnetron sputtering in a mixed atmosphere of Ar and O2 at fixed 5mTorr working pressure. A 13% enhancement (blue shift) in band gap from 3.59eV to 4.06eV was obtained as O2/Ar flow ratio increased from 5% to 50%. a-HIZO films deposited at higher O2/Ar gas flow ratio were more resistive. Oxygen-incorporation-induced reduction of oxygen vacancies is suggested to explain the band gap and resistivity increase.