Abstract
We report the electric field and pH sensitivity of fluid gated metal-semiconductor hybrid (MSH) Schottky structures consisting of a Titanium layer on n-type GaAs. Compared to standard field-effect sensors, the MSH Schottky structures are 21 times more sensitive to electric field of −46.6 V/cm and show about six times larger resistance change as pH of the solution is decreased from 8.17 to 5.54. The potential change at the fluidic gate and passivation layer interface by bias voltages and pH are mirrored by the metal shunt, resulting in larger depletion widths under the Schottky junction and resistance change as compared to sensors with no Schottky junction. 2D numerical simulation results are in good agreement with the measured data and suggest thinner mesa with lower doping density can further increase device sensitivity.
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Acknowledgements
This work was supported by the U.S. NIH under Grant 1U54CA11934201. S.A.S. also received support from the U.S. NSF under Grant ECCS-0725538. S. A. S., S. A. W., and K. D. W. are cofounders of and have a financial interest in PixelEXX, Inc. a start-up company whose mission is to market imaging arrays. W.J.C. was partially supported from the ERC for Advanced Bioseparation Technology, KOSEF, Korea. Two of the authors (W.J.C. and H.J.S.) contributed equally to this work.
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Chang, WJ., Suk, HJ., Newaz, A.K.M. et al. Fluidic measurement of electric field sensitivity of Ti-GaAs Schottky junction gated field effect biosensors. Biomed Microdevices 12, 849–854 (2010). https://doi.org/10.1007/s10544-010-9439-9
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DOI: https://doi.org/10.1007/s10544-010-9439-9