Real time detection of Hg2+ ions using MoS2 functionalized AlGaN/GaN high electron mobility transistor for water quality monitoring

•A MoS2 functionalized Au gated AlGaN/ GaN HEMT sensor has been developed for the detection of toxic Hg2+ ions.•The synthesis of MoS2 was performed by hydrothermal approach.•The characterization suggests the vertically aligned, flower like MoS2 formation.•The sensor exhibits a rapid response of 1.8 s at 1 ppt, high sensitivity of 0.64 μA/ppb and high selectivity for Hg2+ ions.