Thin layer gas sensor comprises: (a) a heatable metal oxide layer (1); (b) a 1st electrode arrangement (2) contacting the metal oxide layer; and (c) a 2nd electrode arrangement (3) contacting the metal oxide layer. The novelty is that the contact is formed between the 1st electrode arrangement and the metal oxide layer Schottky contact, and between the 2nd electrode arrangement and the metal oxide layer as Ohmic contact. USE - Used as a Schottky diode in the detection of nitrogen oxides, used in air control systems for vehicles.