Semiconductor gas sensor and method for measuring a residual gas component by a semiconductor gas sensor

Semiconductor gas sensor (10) on the basis of a field effect transistor, - having a separated by a gap of a channel region (50) of gas-sensitive control electrode (100) and is designed as a suspended gate FET (SGFET), or - the control electrode (100) is arranged as a first plate of a capacitor with a gap and a second plate (290) of the capacitor having a gate (270) formed as the Capacitve Controlled field effect transistor (CCFET) is connected, and the control electrode (100), a semiconductor base layer (130) or conductive metallic support layer with an overlying primer layer (120) and one on the adhesive layer (120) overlying the gas-sensitive layer (110), and - the surface of the gas-sensitive layer (110) faces the channel region (50) or the second plate (290), characterized, in that the control electrode (100) as the gas-sensitive layer (110) comprises a platinum / gold alloy with a gold content in a range of 1% to 20% and a polymer layer having a thickness below 100 nm is formed on the surface of the platinum / gold alloy, and the gap is filled with an oxygen free gas mixture or a gas mixture with an oxygen content below 0.1%.