International Journal of High Speed Electronics and Systems

In recent years SiC has metamorphisized from an R&D based materials system to emerge as a key substrate technology for a significant fraction of the world production of green, blue and ultraviolet LEDs. Emerging markets for SiC homoepitaxy include high-power switching devices and microwave devices. Applications for heteroepitaxial GaN-based structures on SiC substrates include lasers and microwave devices. In this paper we review the properties of SiC, assess the current status of substrate and epitaxial growth, and outline our expectations for SiC in the future.

Results obtained in recent studies of deep centers in 6H-, 4H-, and 3C-SiC are analyzed. The ionization energies and capture cross sections of centers formed by doping of SiC with different types of impurities or by irradiation, as well as the corresponding parameters of intrinsic defects, are presented. The involvement of these centers in radiative and nonradiative recombination is examined. Analysis of published data shows that a strong influence is exerted by intrinsic defects in the SiC crystal lattice both on the formation of deep centers and on the properties of the epitaxial layers themselves, such as their doping level and polytype homogeneity.

The chapter will give an overview about the theory of JFETs with special attention to the wide band gap issues related to SiC. After a comprehensive discussion of relevant structures and topologies experimental results are presented and discussed. Especially vertical structures are in the focus of this chapter. Characteristic I-V data will be shown as well as application specific solutions regarding the temperature behavior or the ruggedness of the devices. The status of the JFETs technology will be judged and compared to alternative solutions like MOSFEts or lateral JFETs. Finally, an outlook will be given regarding targeted applications for SiC VJFETs and the resulting requirements as targets for future improvements.