The tin oxide thin films were deposited on the Corning 7059 glass by sputtering, chemical mist deposition and spin coating. The influences of different process parameters on the microstructure, electrical-optical and gas-sensing properties were studied to establish their interrelation.
During the sputtering, the total pressure, the partial pressure of oxygen and substrate temperature were varied and dense thin films were obtained. The films possess (110) preferred orientation along with {011} twins. As no doping was attempted, transmittance of the films in the range of visible light is > 85 %. The lowest resistivity is ~1.4¡Ñ10-2 £[-cm. Therefore , they can be used as transparent conductive films. On the contrary, these dense films are not suitable for gas-sensor application.
Chemical Mist Deposition (CMD) method employs SnCl4¡D5H2O dissolved ethanol as starting solution. The flow rate of carrier gas, substrate temperature and deposition time were varied to obtain films of different features. Below 350¢J of substrate temperature, the deposition films are amorphous, while SnO2 crystalline films are obtained when temperature above 400¢J. As (110) preferred orientation increases with deposition temperature. The films transmittance decrease with increasing thickness as well as porosity and maintains at a level around 85 %. The lowest resistivity of undoped films is 1.2¡Ñ10-2 £[-cm. These characteristic render them as good transparent conductive films. As dense films with negligible porosity, the sensitivity for CO gas detection of these films is less than 2 when thickness is less than 100 nm and can not serve as a decent gas sensor.
Porous films were obtained using spin-coating. No preferred orientation is found in these films. As porosity is high, the optical transmittance and electrical conductance are low. SnCl4¡D5H2O dissolve in DI water (with NH3(aq) added for promotion of hydrolysis) was used as starting solution. The starting solution contains large amounts of electrolytes of NH4+ and Cl-, and the resultant films contain large amounts of small cracks with low surface area. The sensitivity of CO gas is 3~4. If the electrolytes are eliminated before deposition, finer cracks are obtained in the films with increased surface area, and the sensitivity for CO gas detection can reach 12.9.
Meso-structure precipitates were obtained when the starting solution was mixed with CTAB(aq). The resultant solution yield films of high surface area and sensitivity for CO gas can reach 16.1, rendering them as good gas sensors.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0623103-150519 |
| Date | 23 June 2003 |
| Creators | Chen, Chi-San |
| Contributors | Bae-Heng Tseng, Y.C. Chen, Tzu-Chien Hsu, Jeh-Jeng Wang, Hong-Yang Lu, Bing-Hwait Hwang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0623103-150519 |
| Rights | unrestricted, Copyright information available at source archive |
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