Design and Development of Gallium Nitride HEMTs Based Liquid Sensor

This paper reports on the design and fabrication of Gallium Nitride HEMTs based liquid sensor. Sensor is packaged using thick film Alumina based packaging. A drain current of 6.17 mA is measured on packaged HEMTs at 1.0 V. The packaged HEMT sensor is used for the sensing of different polar liquids namely Acetone, Water, and Methanol. It shows reduction in the drain current as the dipole moment of the liquid increases. Lowest drain current is recorded when the package is dipped into Acetone as compared to Water and Methanol. Four different designs (50_G, 50_ID, 25_G and 25_ID) of sensors are used to detect heavy metal ion Hg+2. The detection limit of design 25_G, 50_G and 50_ID is found to be in mM range. Best results are obtained on design 25 _ ID which shows a 4.8 % change in the drain current with respect to dry response for nM concentration. Not to mention, design “25_ID” is novel and has never used before for the HEMT sensing. Design is unique in the sense of having multiple gates arranged in the electrode fashion.