Abstract
Nanocrystals of lead sulfide were grown in TiO2 (titania) thin films prepared by a sol-gel process. The synthetic procedure as well as the structural, optical, and electrical properties of the films are demonstrated. The structures and morphology of PbS nanocrystals were analyzed using HRTEM, SAED, AFM, HRSEM, XRD and EDAX elemental analysis technique. When the concentration of PbS in the titania matrix is 20 mol%, PbS NCs with a diameter of 2.0 nm are created. At a higher PbS concentration (> 40 mole%) in the titania matrix, PbS NCs and PbS clusters are created not only within the TiO2 film but also on the external surface of the TiO2 film. By increasing the PbS concentration up to 50 mol%, PbS nanocrystals of 6-8 nm in diameter are formed within the titania film and PbS clusters with a base size of about 100 nm2 and a height up to about 20 nm were self assembled on the external surface of TiO2 film. Quantum size effect and band gap energies were obtained from shifts of the absorption edge. For electrical measurements, PbS-TiO2 films were deposited on an ITO/glass substrate, and then covered with gold contact. The electrical properties of ITO/PbS NCs-TiO2/Au and ITO/PbS NCs-TiO2/PbS cluster/Au structures were studied. I-V characteristics of the one layer structure are nearly linear and symmetric, while those of the two-layer structure exhibit rectifying behavior.
Original language | English |
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Pages (from-to) | 87-95 |
Number of pages | 9 |
Journal | Journal of Sol-Gel Science and Technology |
Volume | 44 |
Issue number | 2 |
DOIs | |
State | Published - 1 Nov 2007 |
Externally published | Yes |
Keywords
- AFM and HR-SEM characterization
- Band gap
- Electrical measurements
- External surface
- HR-TEM
- Optical properties
- PbS clusters
- PbS nanocrystals
- Porosity
- Sol-gel process
- Titania thin film
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- General Chemistry
- Biomaterials
- Condensed Matter Physics
- Materials Chemistry