Gate voltage

Figure Bl.22.4. Differential IR absorption spectra from a metal-oxide silicon field-effect transistor (MOSFET) as a fiinction of gate voltage (or inversion layer density, n, which is the parameter reported in the figure). Clear peaks are seen in these spectra for the 0-1, 0-2 and 0-3 inter-electric-field subband transitions that develop for charge carriers when confined to a narrow (<100 A) region near the oxide-semiconductor interface. The inset shows a schematic representation of the attenuated total reflection (ATR) arrangement used in these experiments. These data provide an example of the use of ATR IR spectroscopy for the probing of electronic states in semiconductor surfaces [44]-...

Fig. 6. (a) Transfer characteristics of (b) i -Si TFT element. The drain current, / is plotted against the gate voltage, for three drain potentials A,... 

Fig. 8. Schematic illustration of the tunnelling in a CNT-based device (a) under no bias voltage, there are no orbitals available for conduction, (b) with small bias voltage, only one molecular orbital of a CNT contributes to the carrier transport and (c) when the next molecular orbital enters the bias window, current increases stepwise. Gate voltage can shift all the orbitals upward or downward. AE indicates the energy separation of molecular orbitals.

As described above, metallic CNTs are of great interest because they possess molecular orbitals which are highly delocalised. However, metallic CNTs are very difficult to use in actual devices because they require very low temperatures to control their carrier transfer. On the contrary, even at room temperature, the nonlinear /-V jas curve and the effective gate voltage dependence have been presented by using individual semiconducting SWCNTs [29]. 

Here, the flat-band potential was neglected.) A typical set of drain current-voltage curves for various gate voltages is shown in Figure 14-8. 

It is seen that for a given (constant) gate voltage, the drain current first increases linearly with the drain voltage (linear regime), then gradually levels off to reach a saturation value (saturation regime). 

Figure 14-9. Schematic view of normally on (a) and normally off (b) MESFETs at zero gate voltage. In (a) a conducting channel already exists, while in (b) the depletion layer extends all over the channel.

Figure 14-22. Variation of the square root of the saturation current as a function of the gate voltage for a typical lightly doped DH6T OFET.

Figure 14-24. Variation of the mobility as a function of gated voltage of vacuum-evaporated 6T and 8T. Data were corrected for the contact resistance (from Ref. [78]).

Here, is an effective overlap parameter that characterizes the tunneling of chaiges from one site to the other (it has the same meaning as a in Eq. (14.60)). T0 is the characteristic temperature of the exponential distribution and a0 and Be are adjustable parameters connected to the percolation theory. Bc is the critical number of bonds reached at percolation onset. For a three-dimensional amorphous system, Bc rs 2.8. Note that the model predicts a power law dependence of the mobility with gate voltage. 

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