Localized Charge Transfer Process and Surface Band Bending in Methane Sensing by GaN Nanowires

TL;DR

This study investigates how surface defects in GaN nanowires influence methane sensing, revealing localized charge transfer mechanisms and the role of defect complexes through experimental and simulation analyses.

Contribution

It demonstrates the specific defect complexes responsible for charge transfer in methane sensing and distinguishes between localized and global sensing responses in GaN nanowires.

Findings

Defect complexes VGa-3ON and 2(ON) are present in oxygen-rich GaN nanowires.

Localized charge transfer involves VGa-3ON defects on nanowire surfaces.

Surface defects significantly influence methane sensing behavior.

Abstract

The physicochemical processes at the surfaces of semiconductor nanostructures involved in electrochemical and sensing devices are strongly influenced by the presence of intrinsic or extrinsic defects. To reveal the surface controlled sensing mechanism, intentional lattice oxygen defects are created on the surfaces of GaN nanowires for the elucidation of charge transfer process in methane (CH4) sensing. Experimental and simulation results of electron energy loss spectroscopy (EELS) studies on oxygen rich GaN nanowires confirmed the possible presence of 2(ON) and VGa-3ON defect complexes. A global resistive response for sensor devices of ensemble nanowires and a localized charge transfer process in single GaN nanowires are studied in situ scanning by Kelvin probe microscopy (SKPM). A localized charge transfer process, involving the VGa-3ON defect complex on nanowire surface is attributed in controlling the global gas sensing behavior of the oxygen rich ensemble GaN nanowires.