Zinc oxide-based thin film functional layers for chemiresistive sensors
2012 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, no 21, 6669-6676 p.Article in journal (Refereed) Published
Sol–gel wet-chemical techniques were used to prepare ZnO, Al–ZnO (Al:Zn = 1:10 mol/mol) and Cu–ZnO (Cu:Zn = 1:10 mol/mol) thin films for characterization as functional layers for chemiresistive oxygen sensors. Cu and Al minor components influence the ZnO films' topography and their thermally induced chemical and structural evolution. As prepared (room temperature) films have the structure of layered basic zinc acetate, a lamellar ZnO precursor. Upon annealing at temperatures through 973 K, the films display similar chemical evolution patterns—temperatures above 773 K are needed to completely desorb solvents and decompose precursors. Cu facilitates c-axis orientation of the film as its structure matures, while Al slows its crystallization. Chemiresistive sensors, fabricated by coating thin film functional layers onto interdigitated electrode (IDE) transducers, were evaluated for their responses to oxygen at operating temperatures through 873 K. A ZnO/IDE sensor displays high sensitivity for O2 at an intermediate temperature, 673 K, reflecting an optimal balance between surface O2 coverage and carrier availability. At 1:10 mol/mol Cu:Zn and Al:Zn, the developing ZnO structure cannot accommodate all minor component atoms. Surplus atoms accumulate in independent phases at grain boundaries, contributing to both high base resistances (in N2) and low sensitivity to oxygen.
Place, publisher, year, edition, pages
Elsevier, 2012. Vol. 520, no 21, 6669-6676 p.
Thin films; Chemiresistive sensors; Sol–gel; Zinc oxide; Structural evolution
Engineering and Technology Materials Engineering Physical Sciences
IdentifiersURN: urn:nbn:se:liu:diva-88522DOI: 10.1016/j.tsf.2012.07.016OAI: oai:DiVA.org:liu-88522DiVA: diva2:604673