Gate device

The principle of the depletion regime is quite similar to that occurring in MES-FETs, with the difference that, unlike the MESFET, the TFT is an insulated gate device [15]. Accordingly, Eq. (14.36), which gives the width of the depletion layer, changes to... 

As an alternative, top gated devices contacted with TiC show ambipolar behavior and better stability [167, 168]. Ambipolar transistors, however, cannot be used to reproduce the current CMOS technology where both p-type and n-type transistors are used because the combination of the two has superior performance and lower power consumption than devices built with only one type of transistor. An alternative solution was recently presented and consists of selectively applying negative or positive gate voltages to CNT ambipolar transistors, which make them behave as p-type or n-type respectively [169]. 

D. Filippini, J. Gunnarsson and I. Lundstrom, Chemical image generation with a grid-gate device, J. Appl. Phys., 96(12) (2004) 7583-7590. 

Our TFT technology is based on a bottom-gate device architecture (Fig. 14.2). This geometry is comparable with the inverted staggered-electrode structure com-... 

The drain current in three-gate MOSFETs is found to be lower than in conventional ones. It may be explained by fact that in the three-gate devices the electron concentration has more complex dependence on Vq ( 20)-... 

In conclusion, some properties of three-gate MOSFETs are studied in comparison with those of conventional single-gate MOSFETs. By means of Monte Carlo simulation it is shown that electron mobility in the three-gate devices in certain cases may be higher than in conventional MOSFETs, where the increase of drain current is not observed. 

The ability to deposit parylene C dielectrics using vapor phase deposition methods makes it very useful for sensitive semiconductors (in the case of top gate devices), such as single crystals. Researchers at Rutgers and Bell Labs have made extensive use of this dielectric in single-crystal field-effect transistors [56,57]. 

FIGURE 6.2.3 Structure of a sensing OTFT. It is a typical bottom gate device where the polycrystalline organic thin film acts at the same time both as active layer and sensing membrane directly exposed to the analyte to be revealed. 

OTFT sensors have device structures and detection mechanisms different from those of CHEMFETs. In the case of OTET sensors, the analyte detection is performed employing a bottom gate device structure where the active layer is directly exposed to the analyte and acts as both transistor channel material and sensing membrane. 

Fig. 6.6. Structure of an ion-sensitive organic field-effect floating gate device for chemical sensing [7]. Copyright 2006 IEEE...

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