Metal-oxide-semiconductor field-effect transistor, characteristics

One of the easiest ways to visualize the material and device characteristics that need to be measured is to consider a semiconductor device. For this I have chosen in Figure 1 a metal-oxide-semiconductor field-effect transistor (MOSFET) as representative of a typical semiconductor device. Indicated on it are the important material and device parameters that need to be measured. Only some of them are addressed in this chapter. Other devices could have been chosen, but the MOSFET incorporates most ot the parameters of interest and is the most coismon integrated circuit device. 

FIGURE 8.5 Schematic diagram and current-voltage (I-V) characteristics of (a) metal-semiconductor field-effect transistor (MESFET) and (b) metal-oxide semiconductor field-effect transistor (MOSFET). 

The FET characteristics described here differ from those of conventional metal-oxide-semiconductor field-effect transistors (MOSFETs) [208] in the following aspects ... 

The source and drain are both p-type if the current flowing is holes. Surface field effect transistors have become the dominant type of transistor used in integrated circuits, which can contain up to one billion transistors plus resistors, capacitors, and the very thinnest of deposited connection wires made from aluminum, copper, or gold. The field effect transistors are simpler to produce than junction transistors and have many fevorable electrical characteristics. The names of various field effect transistors go by the abbreviations MOS (metal-oxide semiconductor), PMOS (p-type metal-oxide semiconductor), NMOS (n-type metal-oxide semiconductor), CMOS (complementary metal-oxide semiconductor—uses both p-type unipolar and n-type unipolar). 

Fig. 1.8 Classical schematic drawing illustrating the hydrogen-sensitive Schottky diode-based, capacitance-based, and field-effect transistor-based devices, in which hydrogen atoms adsoibed at the metal-semiconductor or meted oxide interface cause a shift of the electrical characteristics along the voltage axis in devices having catalytic meted (Pd) gates...

As a matter of fact, the observed degradation in the device parameters occurs with the first indication of a metallic fraction in the Ca adsorbate. Even more, the device performance is significantly degraded as soon as the Ca characteristic Ca2p3/2 and Ca2pi/2 emission lines are clearly developed. This implies that the availability of metallic Ca at the dielectric interface, even in small quantities, has a negative effect on the electron transport along the dielectric-semiconductor interface. It is likely that the metallic fraction in the oxidized Ca layer disturbs or even fully screens the electric field in the transistor channel. 

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