Metal contacts to wide bandgap semiconductor structures for RF power applications

The increasing demand for electronic devices capable of function at high power and frequency levels, high temperatures, and harsh environment is one of the most significant issue of modern information society, especially in the field of RF systems for telecommunication and wireless communication. Moreover, energy problems and environmental concerns due to global warming have generated the need for novel semiconductor devices for active electrical power management in areas such as energy generation and distribution, and transport where efficiency and/or high temperature operation are of the essence. Wide bandgap semiconductor devices, particularly those using SiC and GaN-based materials, are key candidates for power-control and highspeed communication devices, owing to their excellent intrinsic properties, which involve large breakdown electric field, in the 5×10
⁶
Vcm
^-1
range, together with high electron saturation drift velocity, strong hardness, and good thermal conductivity. GaN is already used in high-frequency circuits and is attracting increasing attention as a material to play a leading role in the next generation of power electronics. On the other hand, much effort have been already put in SiC technology and first SiC power devices have already been commercialised. Moreover, SiC is the favourite substrate for GaN-based high-power and high-frequency applications. SiC also appears as enabling platform for large area graphene electronics, while a radio-frequency graphene transistor with the cut-off frequency 100 GHz have been demonstrated this year.