Field-effect transistor capacitance

Judd-Hunter color difference scale, 7 321 Juglone, in skin coloring products, 7 847 Juglone derivatives, 21 264-265 Juice softening, 23 463 Junctional heart rhythm, 5 107 Junction capacitance, 22 244 Junction devices, 22 180-181 Junction FETs (JFETs), 22 163, 164. See also Field effect transistors (FETs) physics of, 22 241-245, 249 Junction potentials, 9 582 Junctions, stacking, 23 38-39. See also Josephson junctions p-n junction Just-in-Time technique, 21 172 Jute, 11 287, 288, 292, 293. See also China jute... 

The measurement of changes of the surface potential Vo at the interface between an insulator and a solution is made possible by incorporating a thin film of that insulator in an electrolyte/insulator/silicon (EIS) structure. The surface potential of the silicon can be determined either by measuring the capacitance of the structure, or by fabricating a field effect transistor to measure the lateral current flow. In the latter case, the device is called an ion-sensitive field effect transistor (ISFET). Figure 1 shows a schematic representation of an ISFET structure. The first authors to suggest the application of ISFETs or EIS capacitors as a measurement tool to determine the surface potential of insulators were Schenck (15) and Cichos and Geidel (16). 

FET type humidity sensor. Although sensors based on a field-effect transistor (FET) appear to hold promise as a small and low-cost intelligent sensor, relatively few people have been engaged in the research on FET type sensors in Japan. In this respect, it is remarkable that a FET type humidity sensor was developed recently by Hijikigawa of Sharp Corp (9). The sensor is also worth notice as a new type of humidity sensor, which utilizes changes in electric capacitance of humidity sensitive membrane interposed between double gate electrodes. 

For practical purposes, the very small signals generated by pyroelectric elements must be amplified. The most widely used first stage consists of a field effect transistor (FET) which responds to electric potential rather than to charge. In this case, it is advantageous for the material to have a low permittivity to match the low input capacitance of the FET. Therefore the compositions with high... 

In the standard metal-oxide semiconductor field-effect transistor (MOSFET) drain-current equations, is a proportionality factor that relates the drain current /p, to the gate and drain voltages and V[)s, respectively the threshold voltage V, the channel width W and length L and the gate dielectric capacitance per unit area Cox. The standard drain-current equation for an -channel device in the linear region of operation - V) is [4]... 

Fig. 12.13 An organic thin-film field-effect transistor, schematic. The current Id in a weakly semiconducting organic film (black) between two electrodes S (source) and D (drain) can be controlled by the gate (G) voltage Vc- The latter influences charge carriers capacitively in a thin layer of the...

---