Source-Drain measurements

One step further to tune the electronic properties of a 2-D array of Ag nanoparticles with a size distribution of 7% was reported by Remade et al. [94]. These authors discussed the experimental and computational results of temperature-dependent conductivity measurements as a function of size distribution, compression of the array, and the applied gate voltage. From the temperature-dependent source-drain measurements they obtained sigmoidal-shaped and nonlinear curves (Figure 5.65). 

Figure 6A Schematic depiction of source and drain current versus drain potential when the source potential is fixed at a value much less than the formal potential of the redox cofactors calculated using Equation 6.9 (i.e., source-drain measurement) [6]. Lines labeled a-g indicate source and drain current for different drain potentials.

These equations describe an unheated transistor and were verified for a device with no backside etching (no membrane). The modelling parameters were provided by the manufacturer, whereas the value of the threshold voltage was taken from wafer map data. The channel length modulation parameter. A, had to be extracted from measurement data. The discrepancy between simulated and measured source-drain saturation current, fsd,sat> for a transistor embedded in the bulk silicon was less than 1%, which confirmed the vaHdity of the model assumptions. 

Fig. 4.19. Comparison between measured T-versus-Vsg characteristics and the MOSFET-heater model data for a source-drain voltage of 5 V...

The relative deviation between measurement results and the temperature-depen-dent MOS transistor model data was less than 10% above 100 °C. In the case of a source-drain bias of 5 V it appeared that the model described the real situation well up to 300 °C, but then started to deviate. 

The electrical current flows from the source, via the channel, to the drain. However, the channel resistance depends on the electric field perpendicular to the direction of the current and the potential difference over the gate oxide. Should this surface be in contact with an aqueous solution, any interactions between the silicon oxide gate and ions in solution will affect the gate potential. Therefore, the source-drain current is influenced by the potential at the Si02/aqueous solution interface. This results in a change in electron density within the inversion layer and a measurable change in the drain current. This means we have an ion-selective FET (an ISFET), since the drain current can be related to ion concentration. Usually these are operated in feedback mode, so that the drain current is kept constant and the change of potential compared to a reference electrode is measured. 

The electrical stability of the TFT was measured using dc bias followed by a pulsed recovery measurement. The dc bias conditions were applied with the gate potential set at 20 V and the source/drain bias at 1 V. The devices were stressed for 60 min followed by the pulsed recovery measurement having an on-time pulse of 25 ms. and an off time of 10 s. Figure 11.17 shows the measurement of the... 

Most measurements by the FE method have been made in the hole accumulation layer formed in the channel on application of a voltage between the gate and the source. Drain... 

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