2.4.1 Choice of Polytype for Devices

As discussed in Section 2.3, 4H-SiC and 6H-SiC are the far superior forms of semiconductor device quality SiC commercially available in mass-produced wafer. Therefore, only 4H-SiC and 6H-SiC device processing methods will be explicitly considered in this section. It should be noted, however, that most of the processing methods discussed in this section are applicable to other polytypes of SiC, except for the case of 3C-SiC grown on silicon where all processing temperatures need to be kept well below the melting temperature of silicon (1412$~^{\circ}$C).

It is generally accepted that 4H-SiC's substantially higher carrier mobility and shallower dopant ionization energies compared to 6H-SiC (Table 2.3) should make it the polytype of choice for most SiC electronic devices, provided that all other device processing, performance, and cost-related issues are roughly equal between the two polytypes. Furthermore, the inherent mobility anisotropy that degrades conduction parallel to the crystallographic c-axis in 6H-SiC [72] particularly favors 4H-SiC for vertical power device configurations (Section 4.5.2). T. Ayalew: SiC Semiconductor Devices Technology, Modeling, and Simulation