Thickness dependence of transport properties of doped polycrystalline tin oxide films

Journal Article · Sat Jun 01 00:00:00 EDT 1985 · J. Electrochem. Soc.; (United States)

DOI:https://doi.org/10.1149/1.2114132· OSTI ID:5161069

Belanger, D; Dickson, J I; Dodelet, J P; Lombos, B A

Tin oxide films were deposited by chemical vapor deposition on borosilicate and fused silica substrates using dibutyltin diacetate (DBTD) as tin feedstock and SbC/sub 5/ or CC/sub 3/-CF/sub 3/ as dopants. The film growth rate was measured as a function of dopant/DBTD ratio, temperature, and film thickness. Scanning electron microscopy and x-ray diffraction spectra of the films were used to determine the grain sizes and the preferential orientations of the crystallites in the film as a function of film thickness. Optical and electrical properties were measured. A model is proposed to elucidate the variation of transport properties of doped SnO/sub 2/ as a function of film thickness. It could b shown with this model that the thickness dependence of the conductivity of doped SnO/sub 2/:Sb and SnO/sub 2/:F films could be analyzed in terms of carrier concentration taking into consideration deep-level compensation. The number of carriers is decreased by electron trapping at Sb(III) or Sn(II) surface states when antimony or fluorine are used as dopant, respectively. The model based on results of the literature related to a single crystal with (110) orientation is extended in this work to other crystallite orientations. The present analysis indicates that deep levels appear only on the grain boundary surfaces with (110), (211), and (301) orientations, and not on the (200) and (400) ones. The concentration of free carriers can be calculated on the basis of x-ray diffraction spectra indicating an estimate of the relative fraction of the crystallites with each orientation as a function of the film thickness. The conductivities of the films can be computed using this model and taking a single value for the electron mobility of 19 cm/sup 2/ (V-s)/sup -1/ for all film thickness and a total donor concentration of 2 x 10/sup 20/ cm/sup -3/. All the obtained experimental data can be accounted for exclusively on the basis of film-thickness dependent carrier concentration.

• Research Organization: INRS-Energie, Varennes, Quebec
• OSTI ID: 5161069
• Journal Information: J. Electrochem. Soc.; (United States), Vol. 132:6
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
TIN OXIDES
CARRIER DENSITY
ELECTRIC CONDUCTIVITY
ANTIMONY
CHEMICAL VAPOR DEPOSITION
CRYSTAL GROWTH
CRYSTAL MODELS
DOPED MATERIALS
ELECTRON MOBILITY
FILMS
FLUORINE
OPTICAL PROPERTIES
POLYCRYSTALS
SCANNING ELECTRON MICROSCOPY
THICKNESS
X-RAY DIFFRACTION
CHALCOGENIDES
CHEMICAL COATING
COHERENT SCATTERING
CRYSTALS
DEPOSITION
DIFFRACTION
DIMENSIONS
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
ELEMENTS
HALOGENS
MATERIALS
MATHEMATICAL MODELS
METALS
MICROSCOPY
MOBILITY
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PARTICLE MOBILITY
PHYSICAL PROPERTIES
SCATTERING
SURFACE COATING
TIN COMPOUNDS
360603* - Materials- Properties