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Gate-Bias Controlled Charge Trapping as a Mechanism for NO2 Detection with Field-Effect Transistors

Anne-Marije Andringa, Juliaan R. Meijboom, Edsger C. P. Smits, Simon G. J. Mathijssen, Paul W. M. Blom and Dago M. de Leeuw, Weinheim (2010)

Detection of nitrogen dioxide, NO2, is required to monitor the air-quality for human health and safety. Commercial sensors are typically chemiresistors, however field-effect transistors are being investigated. Although numerous investigations have been reported, the NO2 sensing mechanism is not clear. Here, the detection mechanism using ZnO field-effect transistors is investigated. The current gradually decreases upon NO2 exposure and application of a positive gate bias. The current decrease originates from the trapping of electrons, yielding a shift of the threshold voltage towards the applied gate bias. The shift is observed for extremely low NO2 concentrations down to 10 ppb and can phenomenologically be described by a stretched-exponential time relaxation. NO2 detection has been demonstrated with n-type, p-type, and ambipolar semiconductors. In all cases, the threshold voltage shifts due to gate bias induced electron trapping. The description of the NO2 detection with field-effect transistors is generic for all semiconductors and can be used to improve future NO2 sensors.

Partners : Philips

Place of Publication : Weinheim

Date of Publication : 2010/11/15

Additional Data : Adv. Funct. Mater. 2010, XX, 1–8

Link to the online version of the article.