METHOD FOR MEASURING THE GAS-SENSITIVE CHARACTERISTICS OF SEMICONDUCTOR SENSORS BY DYNAMIC RESPONSE PARAMETERS
Abstract
Detection of dangerous gases and vapors is relevant both at work and in everyday life. Sensor elements based on semiconductor structures are highly sensitive to gases of a very different nature. To increase the accuracy of measurements, calibration and the speed of concentration determination, special methods are required, such as signal processing in various ways. The study uses gas sensors based on silicon–carbon films that are sensitive to a whole set of gases. In the first part of the article, general problems and a method for solving them are considered, which makes it possible to increase the selectivity of semiconductor gas sensors. The analysis of dynamic parameters, such as the first and second derivatives of the response curves, as well as the analysis of the Elovich equation is carried out. Such calibration dependences, constructed from the extremes of the derivatives and the slope coefficients of the Elovich equation, show high linearity. As a promising solution, it is proposed to use a set of calibration lines to determine the concentration of the target gas. The developed method allows, using dynamic response parameters, to determine the gas type and its concentration using a single sensor, also to increase the accuracy of measurements, along with a reduction in detection time. The experimental results of data processing with the determination of the gas type and its concentration using the described method are presented. For a sensor based on silicon-carbon materials, the developed method and algorithms made it possible to carry out measurements using a single sensor element for a set of gases (NO2, CO, SO2) with different concentrations. At the same time, the smallest relative error did not exceed 3.6% for SO2, 2.7% for NO2, 2% for CO. The distinctive features of the developed method are the use of several calibration lines in a multidimensional space, rather than one, as well as an original algorithmic signal processing methods.
