High Electrical Conductivity and High Hardness in Cubic Silicon Carbide Single Crystals

The intrinsic trade-off between electrical conductivity and hardness has been a longstanding obstacle in simultaneously enhancing both properties in materials. Here, we report a strategy to overcome this dilemma by utilizing the striking disparity effects of heavy doping on electrical and mechanical properties. A high room-temperature electrical conductivity of 3.03 × 105 S/m is achieved alongside a high nanoindentation hardness of 39.9 ± 1.9 GPa and an elastic modulus of 525.9 ± 13.0 GPa in cubic silicon carbide (3C-SiC) single crystals with a N-doping level of ∼0.5 at %. The unprecedented combination of these two properties in compound semiconductors confirms the disparity effects of N doping, as manifested by a significant increase in electrical conductivity due to a large nitrogen solubility (∼0.5 at %), while there is a negligible impact (∼1% decrease) on hardness upon N doping. This strategy may find applications in other covalent compounds or semiconductors for acquiring both electrical and mechanical properties.