Gas sensor device

A gas sensor device comprising:

• a first electrode;
• a second electrode;
• a metal oxide layer that is disposed between the first electrode and the second electrode and is in contact with the first electrode and the second electrode;
• an interlayer insulating film that covers a part of the first electrode, a part of the second electrode, and a part of the metal oxide layer;
• and
• a hydrogen permeable film that allows only hydrogen to permeate,
• wherein a local region that is in contact with the second electrode is provided inside the metal oxide layer, the local region having higher oxygen deficiency than the other region in the metal oxide layer,
• an opening that exposes a gas contact portion which is a part of a main surface of the second electrode is provided in the interlayer insulating film,
• the hydrogen permeable film is provided to cover at least the gas contact portion,
• the hydrogen permeable film includes a first covering portion that covers the gas contact portion at a bottom of the opening and a second covering portion that covers side walls that define the opening, wherein a thickness of the first covering portion is less than a thickness of the second covering portion,
• the first covering portion is formed to be thinner than the second covering portion,
• the hydrogen permeable film includes at least one selected from Pd, a Pd alloy, a Pd—Cu alloy, and TiN, and
• the gas sensor device further comprises a measurement circuit that measures a change in value of a current flowing through the metal oxide layer due to contact of hydrogen-containing gas with the gas contact portion of the second electrode.