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Sensors 2018, 18(5), 1314;

High Sensitive pH Sensor Based on AlInN/GaN Heterostructure Transistor

School of Electronic Science and Engineering, Nanjing University, Nanjing 210023, China
School of Electronics Engineering, Kyungpook National University, Daegu 702-701, Korea
Authors to whom correspondence should be addressed.
Received: 4 March 2018 / Revised: 12 April 2018 / Accepted: 21 April 2018 / Published: 24 April 2018
(This article belongs to the Special Issue Potentiometric Chemical Sensors)
PDF [5242 KB, uploaded 3 May 2018]


The AlInN/GaN high-electron-mobility-transistor (HEMT) indicates better performances compared with the traditional AlGaN/GaN HEMTs. The present work investigated the pH sensor functionality of an analogous HEMT AlInN/GaN device with an open gate. It was shown that the Al0.83In0.17N/GaN device demonstrates excellent pH sense functionality in aqueous solutions, exhibiting higher sensitivity (−30.83 μA/pH for AlInN/GaN and −4.6 μA/pH for AlGaN/GaN) and a faster response time, lower degradation and good stability with respect to the AlGaN/GaN device, which is attributed to higher two-dimensional electron gas (2DEG) density and a thinner barrier layer in Al0.83In0.17N/GaN owning to lattice matching. On the other hand, the open gate geometry was found to affect the pH sensitivity obviously. Properly increasing the width and shortening the length of the open gate area could enhance the sensitivity. However, when the open gate width is too larger or too small, the pH sensitivity would be suppressed conversely. Designing an optimal ratio of the width to the length is important for achieving high sensitivity. This work suggests that the AlInN/GaN-based 2DEG carrier modulated devices would be good candidates for high-performance pH sensors and other related applications. View Full-Text
Keywords: AlInN/GaN; AlGaN; HEMT; pH sensor; open gate geometry AlInN/GaN; AlGaN; HEMT; pH sensor; open gate geometry

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Dong, Y.; Son, D.-H.; Dai, Q.; Lee, J.-H.; Won, C.-H.; Kim, J.-G.; Chen, D.; Lee, J.-H.; Lu, H.; Zhang, R.; Zheng, Y. High Sensitive pH Sensor Based on AlInN/GaN Heterostructure Transistor. Sensors 2018, 18, 1314.

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