Abstract

In this paper, we report an AlGaN/GaN heterostructure field effect transistor biosensor with enhanced sensitivity at subthreshold regime for streptavidin detection. The AlGaN surface is functionalized by oxidization, silanization, and biotinylation for detection of streptavidin. Using a Pt reference electrode dipped into the buffer as a gate, the device is configured as a field effect transistor that can be operated at different regimes. The sensing results show that the device sensitivity is strongly dependent on the ionic strength in the buffer. The sensitivity can be significantly improved in subthreshold regime in comparison with a floating gate device configuration. With the floating gate configuration, the sensitivity at a streptaviding concentration of 47.3 nM is 11.3% whereas the sensitivity is enhanced to 67.4% at a concentration of 4.73 nM when the device is biased at the subthreshold regime. (