0000000000072649
AUTHOR
A. Chaiyboun
A logarithmic multi-parameter model using gas sensor main and cross sensitivities to estimate gas concentrations in a gas mixture for SnO2 gas sensors
Abstract In a metal-oxide semiconductor gas sensor, the sensitivity of the metal-oxide resistance to concentrations of reducing gases in the surrounding atmosphere is known to be related to adsorption and desorption of gas on the redox reactions between the gas and oxygen. Changes in the electric conductance due to these reactions were measured for tin dioxide semiconductor gas sensors. In this study, we propose a model of gas sensor responding behaviour using a relationship between sensor conductance and gas concentrations in a mixture. A least-squares method fit of measured data was applied to determining the values of coefficients. The proposed method uses main and cross sensitivities th…
CMOS-compatible nanoscale gas-sensor based on field effect
The integration of a solid state gas sensor of the metal oxide sensor type into CMOS technology still is a challenge because of the high temperatures during metal oxide annealing and sensor operation that do not comply with silicon device stability. In the presence of an external electric field sensor sensitivity can be controlled through a change of the Fermi energy level and consequently it is possible to reduce the operation temperature. Based in this effect, a novel field effect gas sensor was developed resembling a reversed insulated : gate field effect transistor (IGFET) with the thickness of gas sensing layer in the range of the Debye length (L D ). Under these conditions the control…
CMOS-compatible field effect nanoscale gas-sensor: Operation and annealing models
Complete modelling of electrically controlled nanoscale gas sensors with Poisson, Wolkenstein, Fokker-Planck and continuity is presented. Based on a plausible Drift explanation we developed suitable models for sensitivity control and operational modes. An onset for CMOS-complying annealing procedures is given.
B7.3 - Field Effect SnO2 Nano-Thin Film Layer CMOS-Compatible
The integration of metal oxide gas sensing layers into CMOS electronic still a challenge especially due to the high operating temperatures that do not comply with silicon transistor limits , even more critical, and metal oxide annealing temperatures. External electric fields will allow control over the energy levels of the sensing layer and thus over adsorption sensitivity, consequently the interaction between gas and sensitive layer is modulated. As the absorbed gas on the surface produces a band bending, it changes conduction paths allowing gas detection through resistance measurements. With this configuration, field switch offers fast desorption and thus handling of low temperature respo…
Drift Modeling of Electrically Controlled Nanoscale Metal–Oxide Gas Sensors
Gas sensors with small dimensions offer the advantage of electrical sensitivity modulation. However, their actual use is hindered by drift effects that exceed those of usual metal-oxide sensors. We analyzed possible causes and found the best agreement of experimental data with the model of internal dopant fluctuations. The dopants are oxygen vacancies exhibiting high drift-diffusion coefficients under the impact of electrical fields. Thus, the width parameters of space charge regions, which again control the sensor current, are undergoing slow changes. Moreover, the dopant distributions cause internal electrical fields that yield drift even after voltage switch-off. This behavior has been p…