Title :
A physically-based model for drift in Al2O3-gate pH ISFET´s
Author :
Jamasb, Shahriar ; Collins, Scott D. ; Smith, Rosesmary L.
Author_Institution :
California Univ., Davis, CA, USA
Abstract :
A physical model is presented which quantitatively describes drift in Al2O3-gate pH ISFET´s. Drift is postulated to be associated with a chemical modification of the Al2O3 surface as a result of exposure to the aqueous electrolyte. The time dependence of drift is modeled by a hopping transport mechanism, known as dispersive transport. Chemical modification of the Al2 O3 surface leads to a change in the overall insulator capacitance with time, which gives rise to a monotonic temporal change in the threshold voltage of the ISFET. The validity of the proposed model is experimentally tested by fitting measured drift characteristics of Al2O3-gate pH ISFET´s and examining the physical plausibility of the fitting parameters
Keywords :
MOSFET; alumina; biomedical equipment; biomedical measurement; biosensors; chemical sensors; ion sensitive field effect transistors; pH measurement; semiconductor device models; Al2O3; Al2O3 surface; Al2O3-gate pH ISFET; ISFET-based biomedical sensor; aqueous electrolyte; blood pH; chemical modification; dispersive transport; drift; fitting parameters; hopping transport mechanism; insulator capacitance; monotonic temporal change; physically-based model; threshold voltage; time dependence; Biomedical measurements; Biosensors; Capacitance; Chemicals; Dielectrics and electrical insulation; Dispersion; Logic; Surface fitting; Testing; Threshold voltage;
Conference_Titel :
Solid State Sensors and Actuators, 1997. TRANSDUCERS '97 Chicago., 1997 International Conference on
Conference_Location :
Chicago, IL
Print_ISBN :
0-7803-3829-4
DOI :
10.1109/SENSOR.1997.635494
