Hydrogen influence on electrical properties of Pt-contacted α-Ga2O3/ -Ga2O3 structures grown on patterned sapphire substrates

Here we report on the influence of various gases on electrical properties of Pt-contacted α-Ga2O3 and α-Ga2O3/ -Ga2O3 structures produced by halide vapor phase epitaxy on planar and patterned sapphire substrates. Pt-contacted α-Ga2O3 structures were highly resistive and exhibited no sensitivity to H...

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Bibliographic Details
Published in:Journal of physics. D, Applied physics Applied physics, 2020-10, Vol.53 (41)
Main Authors: Almaev, A V, Nikolaev, V I, Stepanov, S I, Pechnikov, A I, Chikiryaka, A V, Yakovlev, N N, Kalygina, V M, Kopyev, V V, Chernikov, E V
Format: Article
Language:English
Subjects:
gas sensor
HVPE
I-V characteristics
polymorph
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Summary:Here we report on the influence of various gases on electrical properties of Pt-contacted α-Ga2O3 and α-Ga2O3/ -Ga2O3 structures produced by halide vapor phase epitaxy on planar and patterned sapphire substrates. Pt-contacted α-Ga2O3 structures were highly resistive and exhibited no sensitivity to H2 and other gases. In contrast, α-Ga2O3/ -Ga2O3 structures grown under the same conditions on patterned sapphire substrates exhibited clear and reversible response to H2. The response to H2 was thoroughly investigated at temperatures ranging from 25 °C to 200 °C and at applied biases from 1.5 V to 150 V. The lowest detectable limit of H2 at 125 °C was found to be 54 ppm. Selectivity of Ga2O3 structures against O2, NH3, , 4, and H2O was examined at 125 °C and 200 °C. The structures showed little or no sensitivity to other gases at bias voltages below 7.5 V. Electrical and hydrogen sensing properties of these structures can be explained by a model of two back-to-back connected Schottky diodes which is widely used to describe metal-semiconductor-metal structures. Catalytically active Pt electrodes play an essential role in hydrogen sensing mechanism as they promote dissociation of hydrogen molecules. Accumulation of hydrogen atoms at Pt/ -Ga2O3 interface results in the reduction of the Schottky energy barrier and current increase.
ISSN:0022-3727
1361-6463
DOI:10.1088/1361-6463/ab9c69