5-2-2-2 SiC Semiconductor Electrical Properties

5-2-2-2 SiC Semiconductor Electrical Properties

Owing to the differing arrangement of Si and C atoms within the SiC crystal lattice, each SiC polytype

exhibits unique fundamental electrical and optical properties. Some of the more important semiconductor

electrical properties of the 3C, 4H, and 6H SiC polytypes are given in Table 5.1. Much more

detailed electrical properties can be found in References 11–13 and references therein. Even within a

given polytype, some important electrical properties are nonisotropic, in that they are strong functions

of crystallographic direction of current flow and applied electric field (for example, electron mobility

for 6H-SiC). Dopant impurities in SiC can incorporate into energetically inequivalent sites. While all

dopant ionization energies associated with various dopant incorporation sites should normally be

considered for utmost accuracy, Table 5.1 lists only the shallowest reported ionization energies of each

impurity.

TABLE 5.1Comparison of Selected Important Semiconductor Electronic Properties of Major SiC Polytypes

with Silicon, GaAs, and 2H-GaN at 300 K

For comparison, Table 5.1 also includes comparable properties of silicon, GaAs, and GaN. Because

silicon is the semiconductor employed in most commercial solid-state electronics, it is the standard

against which other semiconductor materials must be evaluated. To varying degrees the major SiC

polytypes exhibit advantages and disadvantages in basic material properties compared to silicon. The

most beneficial inherent material superiorities of SiC over silicon listed in Table 5.1 are its exceptionally

high breakdown electric field, wide bandgap energy, high thermal conductivity, and high carrier saturation

velocity. The electrical device performance benefits that each of these properties enables are discussed

in the next section, as are system-level benefits enabled by improved SiC devices.

 

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