Long Term Drift Observed in ISFET Due to the Penetration of H+ Ions into the Oxide Layer

  • Chinmayee Hazarika
  • Sujan Neroula
  • Santanu SharmaEmail author
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 11942)


Ion Sensitive Field Effect Transistor (ISFET) and related biosensors when undergo prolonged hours of operation, witnesses a temporal change in threshold voltage which is termed as drift. Drift is a secondary effect which leads to instability of the device resulting into inaccuracy in both in vivo and in vitro measurements. Various types of drift have been of great interest for researchers and long term drift is one of its kinds. Long term drift is observed in different sensing layer in ISFET devices of which silicon dioxide (SiO2) gate ISFET witnesses the maximum. This paper presents the modeling and analysis of long term drift observed in ISFET due to diffusion of H+ ions into the oxide layer and the field caused by this penetration. The additional hydrogen ions left after the protonation of dangling bonds penetrate through the sensing layer which results into an electric field that influences the threshold voltage. A physical model has been designed explaining the effect of this penetration of positive ions into sensing layer and simulations of this model has been carried out. This model has been further experimentally validated using a Schottky based ISFET device with SiO2 as the sensing layer. Both the theoretical and experimental data indicates toward the existence of this drift and its prominence can be observed in lower pH values.


Biosensors Diffusion Ion Sensitive Field Effect Transistor Long term drift Threshold voltage 


  1. 1.
    Bergveld, P.: Development of an ion-sensitive solid-state device for neurophysiological measurements. IEEE Trans. Biomed. Eng. 17(1), 70–71 (1970)CrossRefGoogle Scholar
  2. 2.
    Hazarika, C., Sarma, D., Puzari, P., Medhi, T., Sharma, S.: Use of cytochrome P450 enzyme isolated from Bacillus Stratosphericus sp. as recognition element in designing schottky-based ISFET biosensor for hydrocarbon detection. IEEE Sens. J. 18(15), 6059–6069 (2018)Google Scholar
  3. 3.
    Hazarika, C., Sarma, D., Neroula, S., Das, K., Medhi, T., Sharma, S.: Characterisation of a Schottky ISFET as Hg-MOSFET and as cytochrome P450-ENFET. Int. J. Electron. 105(11), 1855–1865 (2018)CrossRefGoogle Scholar
  4. 4.
    Matsuo, T., Esashi, M.: Methods of ISFET fabrication. Sens. Actuators 1, 77–96 (1981)CrossRefGoogle Scholar
  5. 5.
    Chou, J.C., Hsiao, C.N.: Drift behaviour of ISFETs with a-Si: H-SiO2 gate insulator. Mater. Chem. Phys. 63(3), 270–273 (2000)CrossRefGoogle Scholar
  6. 6.
    Hein, P., Egger, P.: Drift behaviour of ISFETs with Si3N4-SiO2 gate insulator. Sens. Actuators B: Chem. 14, 655–656 (1993)CrossRefGoogle Scholar
  7. 7.
    Bousse, L., Bergveld, P.: The role of buried OH sites in the response mechanism of inorganic-gate pH-sensitive ISFETs. Sens. Actuators 6, 65–78 (1984)CrossRefGoogle Scholar
  8. 8.
    Jamasb, S., Collins, S.D., Smith, R.L.: A physical model for threshold voltage instability in Si3N4-gate H+-sensitive FET’s (pH ISFET’s). IEEE Trans. Electron Dev. 45(6), 1239–1245 (1998)CrossRefGoogle Scholar
  9. 9.
    Hazarika, C., Sharma, S.: Survey on ion sensitive field effect transistor from the view point of pH sensitivity and drift. Indian J. Sci. Technol. 10(37), 1–18 (2017)CrossRefGoogle Scholar
  10. 10.
    Topkar, A., Lal, R.: Effect of electrolyte exposure on silicon dioxide in electrolyte-oxide-semiconductor structures. Thin Solid Films 232(2), 265–270 (1993)CrossRefGoogle Scholar
  11. 11.
    Wolf, S., Tauber, R.N.: Silicon Processing for the VLSI Era. Process Technology, vol. 1. Lattice Press, Sunset Beach (1986)Google Scholar
  12. 12.
    Hazarika, C., Sharma, S.: A mathematical model describing drift in SiO2 gate pH ISFET’s due to hydrogen ion diffusion. Int. J. Appl. Eng. Res. 9(23), 21099–21113 (2014)Google Scholar
  13. 13.
    May, G.S., Sze, S.M.: Fundamentals of Semiconductor Fabrication. Wiley, New York (2004)Google Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Chinmayee Hazarika
    • 1
  • Sujan Neroula
    • 2
  • Santanu Sharma
    • 2
    Email author
  1. 1.Department of E.C.EG.I.M.TGuwahatiIndia
  2. 2.Department of E.C.ETezpur UniversityTezpurIndia

Personalised recommendations