Hardness of Bulk Single-Crystal Gallium Nitride at High Temperatures

The hardness of single-crystal gallium nitride at elevated temperatures is measured and compared with that of other semiconductors. A Vickers indentation method was used to determine the hardness under an applied load of 0.5 N in the temperature range 20–1200°C. The average hardness was measured as 10.8 GPa at room temperature, which is comparable to that of Si. At elevated temperatures, GaN shows higher hardness than Si and GaAs. A high mechanical stability for GaN is deduced.