Surface Dependence of pH Sensors on AlGaN/GaN Heterostructure

Abstract

A pH sensor on an AlGaN/GaN heterostructure with differentsurface conditions was developed and evaluated. The averagesensitivity is 49.5, 47.2 and 51.8 mV/pH, respectively, forsamples with i-GaN, p-GaN and n-GaN cap layers on the AlGaNsurface. The average sensitivity is 52.9, 53.5, 54.1, and 55.2mV/pH, respectively, for the samples with an AlGaN surface andAl composition of 22%, 24%, 25%, and 35%. The sensitivity ofthe pH sensor on AlGaN/GaN heterostructure increases if theAlGaN surface is adopted and increases with increasingaluminum composition.