Document Detail

CO gas sensing by ultrathin tin oxide films grown by atomic layer deposition using transmission FTIR spectroscopy.
MedLine Citation:
PMID:  18710189     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Ultrathin tin oxide films were deposited on SiO2 nanoparticles using atomic layer deposition (ALD) techniques with SnCl4 and H2O2 as the reactants. These SnO(x) films were then exposed to O2 and CO gas pressure at 300 degrees C to measure and understand their ability to serve as CO gas sensors. In situ transmission Fourier transform infrared (FTIR) spectroscopy was used to monitor both the charge conduction in the SnO(x) films and the gas-phase species. The background infrared absorbance measured the electrical conductivity of the SnO(x) films based on Drude-Zener theory. O2 pressure was observed to decrease the SnO(x) film conductivity. Addition of CO pressure then increased the SnO(x) film conductivity. Static experiments also monitored the buildup of gas-phase CO2 reaction products as the CO reacted with oxygen species. These results were consistent with both ionosorption and oxygen-vacancy models for chemiresistant semiconductor gas sensors. Additional experiments demonstrated that O2 pressure was not necessary for the SnO(x) films to detect CO pressure. The background infrared absorbance increased with CO pressure in the absence of O2 pressure. These results indicate that CO can produce oxygen vacancies on the SnO(x) surface that ionize and release electrons that increase the SnO(x) film conductivity, as suggested by the oxygen-vacancy model. The time scale of the response of the SnO(x) films to O2 and CO pressure was also measured by using transient experiments. The ultrathin SnO(x) ALD films with a thickness of approximately 10 A were able to respond to O2 within approximately 100 s and to CO within approximately 10 s. These in situ transmission FTIR spectroscopy help confirm the mechanisms for chemiresistant semiconductor gas sensors.
X Du; Y Du; S M George
Related Documents :
790559 - Surface forces in respiratory bronchioles during a first breath-model experiment and so...
23788809 - Assessing pharmacy students' ability to accurately measure blood pressure using a blood...
11810669 - On the parameters affecting the sensitivity of mr measures of pressure with microbubbles.
6611629 - Use of a fractional factorial design to evaluate granulations prepared in a fluidized bed.
20375249 - Insect hygroreceptor responses to continuous changes in humidity and air pressure.
24089519 - Low selection pressure aids the evolution of cooperative ribozyme mutations in cells.
9716239 - A review on blood pressure and ischaemic white matter lesions.
939029 - Studies of blood pressures in children, ages 5-14 years, in a total biracial community:...
20197269 - Orthostatic heart rate and blood pressure in adolescents: reference ranges.
Publication Detail:
Type:  Journal Article     Date:  2008-08-16
Journal Detail:
Title:  The journal of physical chemistry. A     Volume:  112     ISSN:  1520-5215     ISO Abbreviation:  J Phys Chem A     Publication Date:  2008 Oct 
Date Detail:
Created Date:  2008-09-29     Completed Date:  2008-10-27     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9890903     Medline TA:  J Phys Chem A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  9211-9     Citation Subset:  -    
Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, USA.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Accuracy of growth model parameters: effects of frequency and duration of data collection, and missi...
Next Document:  High-resolution microwave spectroscopic and ab initio studies of propanoic acid and its hydrates.