Silicon Carbide as a Platform for Power Electronics

For high-voltage, high-current devices that can be operated at elevated temperatures, silicon carbide (SiC) has been the material of choice. Efforts to produce singlecrystal SiC began 30 years ago, but intrinsic problems in growing high-quality singlecrystal boules free of micropipe defects— micrometer-scale pinholes created by dislocations—have only recently been overcome. A series of developments in crystal growth have made large-area, high-quality SiC substrates readily available for applications such as highfrequency transmitters and solid-state white lighting. Additional reductions in defects in the active region of devices have been achieved through epitaxial approaches, in which singlecrystal layers are grown on the substrate. SiC is now poised as the linchpin to “green energy” that will replace less energy-efficient switches now based on silicon technology. The choice of a semiconductor for switching electrical currents on and off depends on the operating voltage and how much current must be controlled. Silicon is an excellent material for the low-power transistors used in microelectronics, but for high currents and voltages, its implementation becomes complex and thermal management issues arise. The fundamental properties of SiC make it a better choice under these conditions. One reason why SiC has been of fundamental interest to materials scientists is that it exists in more than 200 stacking modifications (polytypes) (1). With the advent of the vapor-phase Lely growth process in 1955, small, high-quality SiC single-crystal platelet

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