4HSiC

4H-SiC is a silicon carbide polytype, defined by a hexagonal crystal structure with a four-layer stacking repeat. It is one of the most extensively studied and used SiC polytypes in power electronics, valued for its combination of a wide bandgap and favorable electronic properties.

The material has a wide bandgap of about 3.26 eV at room temperature, which supports high breakdown voltages and operation at elevated temperatures. Its high thermal conductivity and large critical electric field make it well suited for high-power and high-temperature devices. The electronic structure and anisotropic properties of the hexagonal lattice contribute to relatively high electron mobility in the conduction band along certain crystal directions, which is advantageous for switching devices such as MOSFETs and diodes.

4H-SiC can be grown and processed using methods such as chemical vapor deposition (CVD) and physical vapor transport (PVT). Growth typically occurs on 4H-SiC substrates and uses sources like silane or chlorosilanes combined with hydrocarbons. Doping is commonly n-type, achieved with nitrogen or phosphorus. P-type doping is more challenging due to deep acceptor levels, which limits hole conduction at room temperature. This characteristic influences device design, with many power devices implemented as n-type structures or using specific channel engineering in MOSFETs.

Applications of 4H-SiC include high-power, high-voltage electronic devices (MOSFETs, Schottky diodes, and power modules), high-temperature electronics, and radiation-hard detectors. Although substrates and processing remain costly, 4H-SiC remains a leading material for modern wide-bandgap power electronics due to its combination of wide bandgap, high breakdown strength, and thermal performance.