Thermo-mechanical stability of wide-bandgap semiconductors: High temperature hardness of SiC, AlN, GaN, ZnO and ZnSe

The hardness of single crystals α-SiC, AlN, GaN, ZnO and ZnSe at elevated temperatures was measured by the Vickers indentation method in the temperature range 20-1400°C. The hardness of SiC, AlN, GaN, ZnO and ZnSe is about 25, 18, 11, 5 and 1 GPa, respectively, at room temperature. SiC, AlN and GaN show a decrease in hardness, originating in the beginning of macroscopic dislocation motion and plastic deformation, only at temperature 1200°C. A high thermo-mechanical stability for SiC, GaN and AlN is deduced.