Spectroscopic ellipsometry-based study of optical properties of amorphous and crystalline ZnSnO alloys and Zn{sub 2}SnO{sub 4} thin films grown using sputtering deposition: Dielectric function and subgap states

Journal Article · Thu Apr 07 00:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4945316· OSTI ID:22594562

Ko, Kun Hee; So, Hyeon Seob; Jung, Dae Ho; Park, Jun Woo; Lee, Hosun ^[1]

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1. Department of Applied Physics and Institute of Natural Sciences, Kyung Hee University, Yong-In 17104 (Korea, Republic of)

We investigated the optical properties of amorphous and crystalline zinc tin oxide (ZTO) thin films grown on SiO{sub 2}/Si substrates with varying compositions via a co-sputtering deposition method at room temperature. The co-sputtering targets consist of SnO{sub 2} and ZnO. By varying the relative power ratio of the two targets, we demonstrate the ability to control the Sn and Zn composition of the resulting ZTO thin films. The ratio of [Sn]/([Sn] + [Zn]) atomic compositions was estimated at 11%, 29%, 42%, 54%, and 60%. Using a 600 °C annealing process, the as-grown amorphous ZTO films were transformed into crystalline ZTO films. The dielectric functions were obtained based on the measured ellipsometric angles, ψ and Δ. We determined the dielectric functions, absorption coefficients, and optical gap energies of ZTO thin films with varying compositions. The dielectric functions, absorption coefficients, and optical gap energies of amorphous and crystalline Zn{sub 2}SnO{sub 4} thin films were obtained at 29 at. % of Sn. Subgap states at 1.6 eV (A) and 2.8 eV (B) of ZnSnO alloys and Zn{sub 2}SnO{sub 4} films were found in the imaginary part of the dielectric function spectra. The subgap state intensities were reduced via a nitrogen gas annealing. Possible origins of the observed subgap states will be discussed.

• OSTI ID: 22594562
• Journal Information: Journal of Applied Physics, Vol. 119, Issue 13; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION
AMORPHOUS STATE
ANNEALING
DEPOSITION
DIELECTRIC MATERIALS
ELLIPSOMETRY
NITROGEN
OPTICAL PROPERTIES
SILICA
SILICON OXIDES
SPUTTERING
SUBSTRATES
THIN FILMS
TIN ALLOYS
TIN OXIDES
ZINC ALLOYS
ZINC OXIDES