H2 has received considerable attention as an alternative energy source. The detection of H2 is necessary for its safe use due to its explosive flammability. Pt/AlGaN/GaN HEMT can detect H2 gas by a shift in the threshold voltage (Vth) induced by the formation of a dipole layer upon H2 exposure. However, using the Pt/AlGaN/GaN HEMT, the change of Vth after H2 exposure is as small as ∼0.35 V, indicating a narrow sensing window (ΔVth) for H2 detection. This can cause a detection failure in the case of a dynamically fluctuating gas over time. Here, we demonstrate a significantly widened sensing window of ΔVth (1.8 V) using an extremely thin (∼1 nm) ZnO layer grown by atomic layer deposition on the Pt/AlGaN/GaN HEMT sensors. The enlarged sensing window of ΔVth originated from a decreased work function of ZnO on the Pt gates, which further shifted Vth in the negative direction and led to the formation of a dipole layer upon H2 exposure.
This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, & Future Planning (No. NRF- 2019R1C1C1008577 ), and the Basic Research Laboratory project of the Korean Government (MSIP) (No. NRF- 2020R1A4A1018935 ). This work was also supported by the GRRC program of Gyeonggi province (GRRC AJOU 2016B03 , Photonics-Medical Convergence Technology Research Center ).
