MOSFET enhancement mode

The most important CMOS circuit is the CMOS inverter. It consists of only two transistors - a pair of one n-type and one p-type transistor. Both devices are enhancement-mode MOSFETs, with the threshold voltage of the PMOSFET less than zero and the threshold voltage of the NMOSFET greater than zero. Figure 9.6a-c shows the circuit diagram, the top view and the cross section of the CMOS inverter, respectively. 

The first SiC MOSFETs were fabricated by Suzuki et al [1] in 3C-SiC. At the present time, SiC MOSFET research is carried out by several groups, including Cree Research [2-4] and Westinghouse [5]. Enhancement mode and depletion mode (3-SiC MOSFETs have been fabricated by Palmour et al [3]. Enhancement mode devices with 5 pm gate lengths had a maximum transconductance (gm) of 0.46 mS mm 1 at room temperature (see FIGURES 1 and 2). The devices were operational up to 823 K. 

FIGURE 1 Fabrication steps for an enhancement mode P-SiC MOSFET [3]. 

FIGURE 2 Current-voltage characteristics of enhancement mode P-SiC MOSFETs at room temperature and... 

FIGURE 3 Cross-section of n-channel enhancement mode a-SiC MOSFET [6]. 

FIGURE 8 Cross-section of enhancement mode 6H-SiC p-channel MOSFET at room temperature [6],... 

Fig. 18.4 Cross section of a MOSFET, with symbols at the right. This device is N-channel, is normally off, and works in enhancement mode.

FIGURE 2-19 An (i-channel enhancement mode MOSFET (a) structure, (b) symbol, (c) performance characteristics. 

An ISFET is very similar in construction and function to ann-channel enhancement mode MOSFET (Section 2C-3). The ISFET differs only in that variation in the concentration of the ions of interest provides the variable gate voltage to control the conductivity of the... 

We are calling the new model My. Note that the symbols for enhancement- and depletion-mode MOSFETs are the same. PSpice knows that a MOSFET is either an enhancement- or a depletion-mode MOSFET by the value of the threshold voltage parameter, VtO. 

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