TECHNIQUE RISING SENSITIVITY OF GAS SENSORS Russian patent published in 2001 - IPC

FIELD: analytical chemistry, proximate analysis of dangerous ingredients of air atmosphere of living and production zones. SUBSTANCE: one of key factors of sensitivity of gas sensor is state of surface layer where adsorption occurs, direct contact of semiconductor film with ions of gases present in air atmosphere. Uniform porosity of surface layer has the property of maximum specific working surface. It is established experimentally that annealing temperature of sensors for various types of gases should not substantially exceed critical one at initial stage of formation of structure of semiconductor layer. Isothermal annealing at temperatures above critical temperature leads to nonuniform micro and macro porosity of oxide layer, to local burning through. At same time isothermal annealing in critical point contributes to fixing of maximum conductance of sensor and to stabilization of its characteristics in time. EFFECT: increased sensitivity and selectivity by regulation of annealing cycle. 3 dwg