Silicon carbide for power devices

An overview of the status of SiC technology for power devices is discussed. 4H-SiC is the most desirable SiC polytype for power devices because of its superior electron transport properties. Micropipe defect densities in 4H-SiC have been dramatically reduced, with 0.8 cm^-2 being demonstrated on a 35 mm wafer. Interface trap densities of 1×10¹¹ cm^-2 eV^-1 at the oxide/SiC interface have been achieved, resulting in a high SiC NMOSFET channel mobility of 72 cm²/V-sec. Device lifetimes for SiC n-channel MOSFETs have are projected to be 5 years at 350°C, and time dependent dielectric breakdown of oxides on p-type SiC have lifetimes >700 years at 2 MV/cm and 350°C. Sheet resistivities of <10 kΩ/sq. and p-type contact resistivities less than 10^-5 Ω-cm² have been obtained using high temperature Al⁺ ion implantation, and the first SiC CMOS circuits have been demonstrated using this technology. Power MOSFETs in 4H-SiC have been demonstrated to have specific on-resistances lower than equivalent Si devices, and blocking voltages as high as 800 V have been achieved. The highest power devices to date are 4.2 kW, 700 V 4H-SiC npnp thyristors, and their speed is very high, with a t_rr=105 nsecs and maximum operating frequency of 250 kHz