AlGaN/GaN heterostructure based Pt nanonetwork Schottky diode with water-blocking layer

Abstract

AlGaN/GaN heterostructure-based Pt nanonetwork Schottky metal contact sensors with polydimethylglutarimide (PMGI) encapsulation as a moisture barrier show robust and reliable response to both dry and humid hydrogen exposures, while maintaining excellent hydrogen sensitivity. Due to the large surface area of the Pt nanonetwork, the detection limit was 0.1 ppm of hydrogen at 25 degrees C. The thermally stable PMGI encapsulated diode exhibited significant current change under 500 ppm humid hydrogen ambient without degradation of the response up to similar to 300 degrees C. The hydrogen responsivity of the Pt nanonetwork diode with PMGI water-blocking layer was modelled in the range of 0.1-40000 ppm with a dissociative Langmuir isotherm. The PMGI encapsulated sensor presents an excellent hydrogen selectivity over other gases, including N-2, NO2, CO, CO2, CH4, and O-2 at 25 degrees C.