A GasFET concept for high temperature operation

A new concept for high temperature gas detection with a floating gate field effect transistor (FG-FET) will be presented. The function of the FG-FET is based on measuring work function changes due to an adsorption and desorption process of gas molecules on a sensing film. All existing concepts are working in a temperature range from room temperature up to 200degC. Higher temperature leads to significant leakage current in the transducer electronics and consequently to device breakdown. The new concept has two key benefits. Firstly, a full isolation achieved by using SOI-substrates and secondly a vertical MOSFET with high doping concentrations in the channel region. Both improvements lead to an extension of the temperature range up to 350degC. This increases the range of layers for chemical sensitive gasdetection and allows the operation in hot ambiance.