Detection of different target-DNA concentrations with highly sensitive AlGaN/GaN high electron mobility transistors

• The DNA sensors based on AlGaN/GaN HEMTs have a detection limit of 10−14 mol/L.
• The threshold voltage and drain–source current changes are governed by the Sips adsorption model.
• The maximal threshold voltage shift is used to estimate the effective amount of probe-DNA on the gate.
• The Sips parameter a indicates the DNA adsorption homogeneity.
• The equilibrium constant KA provides information regarding to the kinetics of the DNA hybridization on the gate.

This paper presents the successful detection of different target-DNA concentrations using AlGaN/GaN high electron mobility field effect transistors (HEMTs). The gate was bio-functionalized with two different densities of complementary DNA before application of target-DNA. Dosages of 10−16 mol/L up to the gate saturation were tested. The DNA concentration was increased by a factor of 10 each time, and the transistor transfer characteristics were measured. The threshold voltage shift and drain–source current change depend on target concentration and obey the Sips adsorption model. The AlGaN/GaN HEMTs are highly sensitive to very low target-DNA concentrations with a detection limit of 10−14 mol/L. The gates with a low probe-DNA density were saturated with a lower target-DNA concentration and presented a faster hybridization equilibrium constant.