Title :
Theoretical description of gas/film interaction on SnO/sub x/
Author_Institution :
Dept. of Electr. Eng., Pennsylvania Univ., Philadelphia, PA, USA
Abstract :
A simple depletion model based on the creation and destruction of Schottky oxygen vacancies near the gas-solid interface is shown to adequately account for the free carrier and mobility response of the SnO/sub x/ films reported by S.C. Chang and D.B. Hicks (1986). Expressions for the relationship between the surface potential, bulk carrier concentration and the reducing gas concentration are derived using the standard semiconductor electrostatic surface model and first order kinetic equations for gas/solid interactions. The results obtained indicate that thin-film gas sensors of the SnO/sub x/ variety behave more like a homogeneous system where free carriers dominate the response than as polycrystalline aggregates dominated by mobility variations arising from potential variations at the intergrain boundaries.<>
Keywords :
Schottky defects; carrier density; carrier mobility; chemical variables measurement; electric sensing devices; interface phenomena; reduction (chemical); semiconductor materials; semiconductor thin films; surface chemistry; surface electron states; surface potential; tin compounds; Schottky oxygen vacancies; SnO/sub x/; bulk carrier concentration; depletion model; first order kinetic equations; free carrier; gas/film interaction; gas/solid interactions; mobility; reducing gas concentration; semiconductor electrostatic surface model; surface potential; thin-film gas sensors; Aggregates; Chemicals; Conductors; Electrostatics; Gas detectors; Kinetic theory; Lead; Solid modeling; Temperature measurement; Temperature sensors;
Conference_Titel :
Solid-State Sensor and Actuator Workshop, 1988. Technical Digest., IEEE
Conference_Location :
Hilton Head Island, SC, USA
DOI :
10.1109/SOLSEN.1988.26426
