Ultrasensitive Detection of Phosphate Using Ion-Imprinted Polymer Functionalized AlInN/GaN High Electron Mobility Transistors

In this letter, a first study on phosphate detection based on AlInN/GaN high electron mobility transistors (HEMTs) is presented. The ungated regions of GaN HEMT-based sensors were functionalized with the phosphate ion-imprinted polymer and their sensing behaviors were analyzed by detecting different concentrations of phosphate solutions. The results show that the AlInN/GaN sensor exhibits an ultrasensitive response and a specific recognition to phosphate anion and reaches a detection limit below 0.02 mg/L level, which is much lower than the limited indicator level of 0.1 mg/L for the plankton growth, while the AlInN/GaN sensor shows a higher sensitivity to phosphate anion when compared with the AlGaN/GaN sensor. This ultra-high sensitivity is attributed to the use of thinner barrier layer in the AlInN/GaN heterostructure, which makes 2-D electron gas channel more sensitive to the change of surface charge.