Hydrogen Sensing Performance of ZnO Schottky Diodes in Humid Ambient Conditions with PMMA Membrane Layer

Enhanced hydrogen sensing performance of Pt Schottky diodes on ZnO single crystal wafers in humid ambient conditions is reported using a polymethylmethacrylate (PMMA) membrane layer. ZnO diode sensors showed little change in forward current when switching to wet ambient H conditions with 100% relati...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2020-02, Vol.20 (3), p.835
Main Authors: Jang, Soohwan, Jung, Sunwoo, Baik, Kwang Hyeon
Format: Article
Language:English
Subjects:
Adsorption
Contact angle
Diodes
gas sensor
Gases
Humidity
Hydrogen
Hydrophobicity
Hydroxyl groups
Membranes
Metal oxides
Nitrogen
Permeability
Relative humidity
Room temperature
schottky diode
Schottky diodes
Sensitivity
Sensors
Single crystals
Temperature
Water purification
Water vapor
Zinc oxide
zno
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Summary:Enhanced hydrogen sensing performance of Pt Schottky diodes on ZnO single crystal wafers in humid ambient conditions is reported using a polymethylmethacrylate (PMMA) membrane layer. ZnO diode sensors showed little change in forward current when switching to wet ambient H conditions with 100% relative humidity. This sensitivity drop in the presence of water vapor can be attributed to surface coverage of hydroxyl groups on the Pt surface in humid ambient conditions. The hydrogen sensitivity of PMMA-coated diode sensors recovered up to 805% in wet H ambient conditions at room temperature. The PMMA layer can selectively filter water vapor and allow H molecules to pass through the membrane layer. It is clear that the PMMA layer can effectively serve as a moisture barrier because of low water vapor permeability and its hydrophobicity. In both dry and wet conditions, ZnO diodes exhibited relatively fast and stable on/off switching in each cycle with good repeatability.
ISSN:1424-8220
1424-8220
DOI:10.3390/s20030835