Electrical Properties of Metal-Porous GaAs Structure at Water Adsorption
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This paper reports the morphological, optical, luminescent and electrical properties of electrochemically made porous GaAs in order to evaluate their humidity sensing performance. The obtained porous GaAs exhibits non-homogenous surface morphology, which consists of pyramid-shaped crystallites and micropores. Photoluminescent and FTIR study shows that the surface of such material is covered by an oxide of As and Ga. The impedance spectroscopy was applied to analyze the influence of water vapor on electrical properties of metal-porous GaAs. It was shown that water adsorption results in the Nyquist plots shift to the region of higher frequencies. In humid atmosphere resistance Rv and characteristic time of charge accumulation τ are decreased by 1.4 times and 5 times, respectively; resistance Rb and capacity Cb decreased by 1.4 times and 4.4 times, respectively. The response of the metal-porous GaAs structure to the adsorption of water is attributed to the decreasing of the bulk resistivity and potential barrier height. The formed oxide layer on the surface of porous GaAs plays a dual role—it increases the ability to adsorb water molecules and prevents the surface from receiving structural degradation.
KeywordsPorous GaAs SEM DRIFT spectrum impedance spectroscopy Nyquist plot humidity sensor
- FTIR spectroscopy
Fourier transform infrared spectroscopy
- DRIFT spectra
Diffuse reflectance infrared Fourier transform spectra
Atomic force microscope
Scanning electron microscope
Full width at half maximum
Constant phase element
X-ray photoelectronic spectroscopy
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The authors wish to thank A. Pastushenko (INSA Lyon) for SEM measurements.
YM and IG carried out the measurements and calculations. AO and MK fabricated the samples of porous GaAs. VS and SP proposed the idea of the work and analyzed the results. All authors have read and approved the final manuscript.
Conflict of interest
The authors declare that they have no competing interests.
The results of these studies were obtained without any sources of funding.
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