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

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 (CH 4 ) sensing. Experimental and simulation results of electron energy loss spectroscopy (EELS) studies on oxygen rich GaN nanowires confirmed the possible presence of 2 2(O N ) and V Ga -3O N 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 V Ga -3O N defect complex on nanowire surface is attributed in controlling the global gas sensing behavior of the oxygen rich ensemble GaN nanowires.

Boosting the performance of NO2 gas sensors based on n–n type mesoporous ZnO@In2O3 heterojunction nanowires: in situ conducting probe atomic force microscopic elucidation of room temperature local electron transport

“…So far, very few reports have attempted SKPM to demonstrate the sensing behaviour of nanomaterials. [28][29][30][31] To the best of our knowledge, this is the rst report on room-temperature local charge transport properties for unravelling the complex mechanism pertaining to NO 2 sensing properties of mesoporous n-n type ZnO…”

Coupling p+n Field-Effect Transistor Circuits for Low Concentration Methane Gas Detection

“…Thus, the trace concentration of methane should be detected fast and reliably in the environment to prevent dangerous explosions. Moreover, in environmental safety, extreme demands are placed on the detection of the potential greenhouse gas methane [ 3 , 4 ]. Recently, various methane sensors have been developed on the basis of catalytic combustion [ 5 , 6 , 7 ], metal oxide semiconductor (MOX) [ 8 , 9 ], infrared spectrum [ 10 , 11 ], gas chromatography [ 12 , 13 ], and optical fiber [ 14 , 15 ].…”

Gallium Nitride (GaN) Nanostructures and Their Gas Sensing Properties: A Review

“…Having a lower explosion limit of 5.0%, methane detection is highly required in both the household and industrial arena [ 50 ]. Patsha et al employed a CVD method in a vapor-liquid-solid process to make GaN NWs [ 51 ]. They introduced different amounts of oxygen in the NWs with varying oxygen impurity concentrations (10 5 ppm, 10 3 ppm, 10 2 ppm and <2 ppm) in order to investigate the role of surface defects formed by the oxygen impurities in methane sensing.…”

“…( B ) Sensor responses of GaN NW at the exposure of CH 4 gas concentrations ranging from 50 ppm to 500 ppm. Figure adapted with permission from [ 51 ], Copyright 2015 American Chemical Society.…”