SILICON CARBIDE (SiC) materials are currently metamorphosing from research and development into a market driven manufacturing product. SiC substrates are currently used as the base for a large fraction of the world production of green, blue, and ultraviolet light-emitting diodes (LEDs). Emerging markets for SiC homoepitaxy include high-power switching devices and microwave devices for S and X band . Applications for heteroepitaxial GaN-based structures on SiC substrates include LEDs and microwave devices. These exciting device results stem primarily from the exploitation of the unique electrical and thermophysical properties offered by SiC compared to Si and GaAs. Among these are: a large bandgap for high-temperature operation and radiation resistance; high critical breakdown field for high-power output; high saturated electron velocity for high-frequency operation; significantly higher thermal conductivity for thermal management of high-power devices.
5-2-1 SiC Material Properties
5-7-1 Future Tied to Material Issues The previous sections of this chapter have already highlighted major known technical obstacles and immaturities that are largely responsible for hindered SiC device capability. In the most general terms, these obstacles boil down to a handful of key fundamental [...]
In solid state physics, a band gap, also called an energy gap or bandgap, is an energy range in a solid where no electron states can exist. In graphs of the electronic band structure of solids, the band gap generally refers to the energy [...]
1-5.Thermal Expansion Coefficient Thermal expansion is the tendency of matter to change in volume in response to a change in temperature. When a substance is heated, its particles begin moving more and thus usually maintain a greater average separation. Materials which contract with increasing temperature are [...]
5-2-1-1 SiC Crystallography Silicon carbide occurs in many different crystal structures, called polytypes. Despite the fact that all SiC polytypes chemically consist of 50% carbon atoms covalently bonded with 50% silicon atoms, each SiC polytype has its own distinct set of electrical semiconductor properties. While [...]
5-5-1 Choice of Polytype for Devices As discussed in Section 4, 4H- and 6H-SiC are the far superior forms of semiconductor device quality SiC commercially available in mass-produced wafer form. Therefore, only 4H- and 6H-SiC device processing methods will be explicitly considered in the rest [...]
2-32.Semi-insulating Semi-insulating Doping with the impurities vanadium creates semi-insulating material of silicon carbide.