Surface and Composition Reactivity of Pt/GaN Catalytic Contact as Schottky Barriers Gas Sensor

Platinum (Pt) Schottky barrier formed on n-GaN is investigated for nitrogen (N₂), hydrogen (H₂) and methane (CH₄) gas sensing applications. The samples are studied for its sensing performance using standard current-voltage forward biased characterisation and these data are correlate to contact grain size and porosity using X-ray diffraction and scanning electron microscope. It is shown that sensor sensitivity not only depends on barrier lowering compound formed at the metal semiconductor junction, but also on the size of the grain and the grain porosity. As such, Pt/n-GaN gas sensor sensitivity is dependent on type of gases and the temperature of the sensor. Maximum sensor sensitivity is achieved at T_device = 250degC with broad sensitivity plateau value from 100degC until 350degC showing the usefulness of Pt/nGaN sensor device at lower operating temperature (<400degC).