Suspended gate field-effect transistor SGFET

SGFET suspended gate field effect transistor... 

The Kelvin probe inspired the design of another solid-state device called the Suspended Gate Field-Effect Transistor (SGFET) (Blackburn et al., 1983). It resembles the Kelvin probe in that the gate conductor is suspended approximately 1 jU m above the gate insulator, thus forming a gap of a capacitor (Fig. 6.30). 

Fig. 6.30 Schematic diagram of the suspended gate field-effect transistor (SGFET). The selective layer is typically deposited electrochemically...

The chemically selective layer can also be deposited inside a narrow gap formed in the gate structure. Thus, the so-called suspended-gate-field-effect transistor (SGFET) can be produced. Besides Pd [111], layers based on polypyrrole, sensitive to hydrogen-bonding gases [112], can be used, in the same way as polypyrrole-nitrotoluene copolymer, selective to aromatic hydrocarbons [113] and Pb phtalocyanine sensitive to NO2 [114]. Discontinuous or perforated Pd-gate FETs can be used for the determination of NH3 [115] or CO [116]. 

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