AlGaN/GaN heterojunction field-effect transistors for suppressing optical artifacts from integrated light-emitting diodes.

The integrated photoelectrode probe capable of simultaneously stimulating neurons with light and collecting electrophysiological signals is the core device of optogenetics. In this paper, AlGaN/GaN heterojunction field-effect transistors (HFETs) are used instead of the traditional metal microelectrode to prepare brain neural probe, and then bonded with the LED photoelectrode probe to form an integrated photoelectrode probe. The AlGaN/GaN HFET structure brain neural probe has high sensitivity and biocompatibility, which can effectively improve the quality of neuronal signal acquisition. While the light stimulation signal of the LED photoelectrode probe will affect the AlGaN/GaN HFET, severely degrading the signal-to-noise ratio (SNR) of neuronal signal acquisition. We prepared multiple pairs of recording HFET (R-HFET) and differential HFET (D-HFET) at the tip of the brain nerve probe. The R-HFET has a bare gate region that is sensitive to changes in extracellular potential and is used for collecting neuronal signals. The gate region of D-HFET is covered with a SiO[Formula: see text] passivation film, which has low sensitivity to changes in extracellular potential and can hardly collect neuronal signals. D-HFET, like R-HFET, is sensitive to the light stimulation signal from the LED photoelectrode probe. By adjusting the drain-source bias of D-HFET and performing differential processing with the signal collected by R-HFET, the neuronal signal can be clearly separated. Simulated biological experiments in phosphate buffered saline solution have shown that the integrated photoelectrode probe can reduce artifacts by 90%.