Studies on the room temperature growth of nanoanatase phase TiO{sub 2} thin films by pulsed dc magnetron with oxygen as sputter gas

Journal Article · Thu Mar 15 00:00:00 EDT 2007 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2714770· OSTI ID:20982775

Karuppasamy, A; Subrahmanyam, A ^[1]

---

1. Semiconductor Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

The anatase phase titanium dioxide (TiO{sub 2}) thin films were deposited at room temperature by pulsed dc magnetron sputtering using pure oxygen as sputter gas. The structural, optical, electrical, and electrochromic properties of the films have been studied as a function of oxygen pressure in the chamber. The x-ray diffraction results indicate that the films grown above 4.5x10{sup -2} mbar are nanocrystalline (grain size of 28-43 nm) with anatase phase. The films deposited at the chamber pressure of 7.2x10{sup -2} mbar are found to be highly crystalline with a direct optical band gap of 3.40 eV, refractive index of 2.54 (at {lambda}=400 nm), and work function of 4.77 eV (determined by the Kelvin probe measurements). From the optical emission spectra of the plasma and transport of ions in matter calculations, we find that the crystallization of TiO{sub 2} at room temperature is due to the impingement of electrons and ions on the growing films. Particularly, the negative oxygen ions reflected from the target by 'negative ion effects' and the enhanced density of TiO, TiO{sup +}, TiO{sub 2}{sup +}, and O{sup 2+} particles in the plasma are found to improve the crystallization even at a relatively low temperature. From an application point of view, the film grown at 7.2x10{sup -2} mbar was studied for its electrochromic properties by protonic intercalation. It showed good electrochromic behavior with an optical modulation of {approx}45%, coloration efficiency of 14.7 cm{sup 2} C{sup -1}, and switching time (t{sub c}) of 50 s for a 2x2 cm{sup 2} device at {lambda}=633 nm.

• OSTI ID: 20982775
• Journal Information: Journal of Applied Physics, Vol. 101, Issue 6; Other Information: DOI: 10.1063/1.2714770; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANIONS
CRYSTAL GROWTH
CRYSTALLIZATION
DEPOSITION
ELECTROCHROMISM
EMISSION SPECTRA
EV RANGE 01-10
GRAIN SIZE
MAGNETRONS
NANOSTRUCTURES
OXYGEN
OXYGEN IONS
REFRACTIVE INDEX
SEMICONDUCTOR MATERIALS
SPUTTERING
TEMPERATURE RANGE 0273-0400 K
THIN FILMS
TITANIUM OXIDES
WORK FUNCTIONS
X-RAY DIFFRACTION