AlGaN/GaN HEMT based sensor and system for polar liquid detection

N. Chaturvedia, K. Singha, P. Kachhawaa, R. Lossyb, S. Mishraa, A. Chauhana, D.K. Kharbandaa, A.K. Jaina, R.R. Thakura, D. Saxenaa, P.K. Khannaa, J. Wuerflb

Published in:

Sens. Actuators, A, vol. 302, pp. 111799 (2020).

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Abstract:

In this paper, a GaN-high electron mobility transistor (HEMT) based sensor is designed, fabricated and characterized for polar liquid sensing. The fabricated HEMT sensor chip is packaged by using low temperature co-fired ceramic (LTCC) technique. The sensor shows a typical drain current of 21.2 mA at 3.3 V. The fabricated sensor shows a percentage change of 1.78%, 2.18% and 6.3% in drain current for mercury chloride, copper chloride and sodium chloride respectively with respect to the drain current of pure water. The readout circuit shows a change of 0.15, 0.20 and 0.34 mA in drain current for acetone, water and methanol respectively and ensures the detection of different polar liquids. Due to the novel inter-digital structure, the sensor shows a sensitivity of 5.98 mA/mm/Debye at a drain voltage of 3.3 V. Sensing mainly depends on the dipole moment because the change in the dipole moment of the liquid causes a change in surface potential at the gate sensing area. This paper gives a theoretical and practical perspective on polar liquid detection using both, the sensor and system.

a CSIR - Central Electronics Engineering Research Institute, Pilani, Rajasthan, India
b Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin, Germany

Keywords:

HEMT, LTCC, Polar liquid sensor, Dipole moment