Non-uniform physical structure model for understanding the electrochromic behavior of tungsten oxide thin films

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6323353

Giri, A P

In all previous studies of electrochromic WO/sub 3/ films, it was implicitly assumed that the film is uniform except for grain boundaries in polycrystalline films. In this study, it is shown that amorphous tungsten oxide films contain highly anisotropic void networks that dominate not only their physical structure (low density voids and high density columns) but also control their electrochromic (EC) behavior. Tungsten oxide and hydrogen doped tungsten oxide films were prepared by reactive r.f. sputtering of tungsten in an atmosphere of Ar, O/sub 2/, and H/sub 2/. The films were reproducible and covered a wide range in composition and physical structure. An electrostatic planar probe was used to study the film bombardment processes and emission spectroscopy and used to study the plasma chemistry. The evolutionary growth of physical structure and details of the void network structures were studied from the near-atomic to ..mu..m level using both transmission and scanning electron microscopy. The composition of virgin and colored films was determined by AES and SIMS analyses. Also, the optical properties and electrical properties of these films were studied. The physical structure of the films was directly related to the bombardment with lower density films obtained under lower bombardment conditions. Particularly at low pressures, ion-bombardment also seems to affect the composition of the films.

• Research Organization: Pennsylvania State Univ., University Park (USA)
• OSTI ID: 6323353
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
AMORPHOUS STATE
CHALCOGENIDES
CHEMICAL PREPARATION
CRYSTAL STRUCTURE
DOPED MATERIALS
ELECTRICAL PROPERTIES
FILMS
HYDROGEN ADDITIONS
MATERIALS
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
SYNTHESIS
THIN FILMS
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
TUNGSTEN OXIDES
VOIDS