Photovoltaic Intelligent Gas Sensors Based on Porous Silicon-crystalline Silicon Heterojunction. Technology and Application

A method of using photo-electromotive forces on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of polar gases at room temperature in the measurement chamber is proposed. The porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to gas concentration in the wide range can be maximized by controlling the intensity of illumination light. The minimum measurement error occurs when the gas concentration magnitude corresponds with the optimal intensity of the illumination light. NI LabVIEW-engineered modules for automatic control was conducted to improve a measurement precision over a wide range of gas. This intelligent gas sensors system with modern wireless network technology could be useful in chemical industry for automatic detection of gas in real time of measurements. Such of photovoltaic gas sensors were checking for ammonia, acetone, ethanol, and mercaptoethanol.