A field effect transistor (FET) sensor for NO2 was fabricated by depositing an NaNO2 layer together with an Au electrode over the gate area. The NaNO2-attached FET exhibited almost ideal FET behavior at 180°C in air. The threshold voltage was found to shift up ward in a well controlled manner with increasing NO2 concentration of the atmosphere. Under the condition of a fixed source-drain voltage (3.0V), the gate-source voltage (VGS) necessary to keep the drain current at a small constant value (200μA) was found to increase linearly with an increase in the logarithm of NO2 concentration in the range from 500ppb to 10ppm. The times of 90% response and recovery to switching-on and -off 500ppb NO2 were about 2 and 4min, respectively. The NO2 sensitivity was hardly or only slightly affected by variations in the concentrations of coexistent O2, CO2 or H2O.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry