Fabrication and Characterization of an Extended-Gate AlGaN/GaN-Based Heterostructure Field-Effect Transistor-Type Biosensor for Detecting Immobilized Streptavidin-Biotin Protein Complexes

Abstract

In this study, we fabricated an AlGaN/GaN-based heterostructure field-effect transistor (HFET)-type biosensor with an extended-gate structure for detecting streptavidin-biotin complexes. The gate voltage of the fabricated device was applied using a commercial Ag/AgCl reference electrode. The binding of a self-assembled monolayer (SAM), streptavidin and biotin was detected by measuring the electrical characteristics of the fabricated biosensor. X-ray photoelectron spectroscopy (XPS) was used to verify the immobilization of the SAM on the Au-coated GaN surface. The proposed biosensor shows that biotin can be detected for a wide range of concentrations from 0.1 to 1000 ng/ml. The long-term stability of both the extended-gate AlGaN/ GaN-based HFET-type and conventional AlGaN/GaN-based HFET-type biosensors was measured in phosphate-buffered saline (PBS) solution. A high sensitivity and excellent stability of the proposed biosensor has been experimentally verified.