Fluidic measurement of electric field sensitivity of Ti-GaAs Schottky junction gated field effect biosensors.
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.
Chang
Woo-Jin
WJ
Department of Electrical and Computer Engineering, Department of Bioengineering, Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Suk
Ho-Jun
HJ
Newaz
A K M
AK
Wallace
Kirk D
KD
Wickline
Samuel A
SA
Solin
Stuart A
SA
Bashir
Rashid
R
D001152:Arsenicals / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D004560:Electricity; D005708:Gallium / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008962:Models, Theoretical; D014025:Titanium / Q000737:chemistry*; D014173:Transistors, Electronic
D001152:Arsenicals; C043055:gallium arsenide; D005708:Gallium; D014025:Titanium