Hydrogen fuel has attracted significant attention as an alternative clean energy for hydrogen vehicles and household fuel systems and has been expected to be pervasive. Thus, compact, low-power, and highly sensitive hydrogen sensors capable of being embedded in Internet-of-Things devices are in demand. In this work, an ultrahigh sensitive hydrogen sensor operating at room temperature based on the Pt-decorated graphene (Pt/Gr) gate AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT) is presented. The proposed unique gate structure of island-like Pt on graphene not only modulates the density of 2-D electron gas (2DEG) but also provides efficient diffusion of hydrogen ions into the gate even at very low concentrations (< 1 ppm) of hydrogen. The fabricated Pt/Gr gate AlGaN/GaN MIS-HEMT hydrogen sensor shows a remarkably high response of ∼ 1.6× 107 in a hydrogen concentration of 1000 ppm at room temperature. Upon exposure of at most 1 ppm hydrogen gas, the current increases significantly by a factor of 15.4, exhibiting an unprecedentedly high hydrogen response. Furthermore, the proposed AlGaN HEMT architecture has an outstanding hydrogen selectivity and insensitivity to NH3, H2S, and CO gases at the same time.
Manuscript received December 22, 2020; revised January 18, 2021; accepted January 18, 2021. Date of publication February 2, 2021; date of current version February 24, 2021. This work was supported in part by the Institute of Information & Communications Technology Planning & Evaluation (IITP) grant funded by the Ministry of Science and ICT (MSIT), Republic of Korea, under Grant 2018-0-00962, in part by the Human Resources Program in Energy Technology of the Korea Institute of Energy Technology Evaluation and Planning via a grant funded by the Ministry of Trade, Industry, and Energy, Republic of Korea, under Grant 20184030202220, and in part by the Nano\u00b7Material Technology Development Program through the National Research Foundation of Korea (NRF) funded by MSIT, Republic of Korea, which was conducted at Korea Advanced Nano Fab Center, under Grant 2015M3A7B7044548. The review of this article was arranged by Editor E. A. Guti\u00e9rrez-D. (Corresponding authors: Geonwook Yoo; Junseok Heo.) Jungho Ahn, Dahee Kim, and Junseok Heo are with the Department of Electrical and Computer Engineering, Ajou University, Suwon 16499, South Korea (e-mail: jsheo@ajou.ac.kr).
