Ultrasensitive Detection of Hg²⁺ Ions With CVD Grown MoS₂-Functionalized MgZnO/CdZnO HEMT

Mercury (Hg) is generally renowned as one of the most dangerous heavy metals, even at trace levels. Its presence can lead to both chronic and acute poisoning, causing severe health issues such as cancer, rheumatoid arthritis, and movement disorders, potentially resulting in death. Current mercury detection systems have several limitations, including slow response times, high costs, and poor portability. In this study, an oxide-based high-electron-mobility transistor sensor has been fabricated by optical lithography and a dual ion beam sputtering (DIBS) system, and it is investigated as a potential sensor for detecting trace amounts of Hg2+ ions in water. Molybdenum disulfide (MoS2) was synthesized via a chemical vapor deposition (CVD) system and transferred to the gate of the MgZnO/CdZnO (MCO) HEMT using an energy-assisted wet transfer method, functionalizing the gate region for Hg2+ ion detection. The fabricated sensor demonstrated excellent selectivity for Hg2+ ions, an outstanding detection limit of 6.5 ppt, a fast response time of lower than 4 s, and an excellent sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9.55~\mu $ </tex-math></inline-formula>A/ppb.