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.
Sang Woon Lee reports administrative support was provided by Ajou University. Sang Woon Lee reports a relationship with Ajou University that includes: employment. Sang Woon Lee has patent pending to Sang Woon Lee.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 ).
