PSI - Issue 23

Atsushi Kubo et al. / Procedia Structural Integrity 23 (2019) 372–377 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

377

6

[0001]

[2¯1¯10] [01¯10]

 2110  tension

 1100  tension

 t

wurtzite



 t





 t

unbuckled wurtzite



 t

rocksalt

Fig. 4. Stress-induced phase transition to high-pressure metastable phases, i.e., rocksalt and unbuckled wurtzite structures.

4. Conclusion

We carried out a series of first-principles tensile tests and evaluated the strengths of ideal crystals for SiC, GaN and AlN polytypes under multiaxial loading conditions. It is revealed that the basic trend in the relationship between the ideal strength and the transverse stress is common in SiC, GaN and AlN, which suggests a possibility of general understanding for deformation and fracture behaviors in similar semiconducting crystals such as zinc oxide (ZnO) and boron nitride (BN). Two types of deformation processes were observed. In a tensile environment, a fracture accompanied with bond breaking is favorable, which may cause an instantaneous failure in devices; while under complex compression and tension, phase transition to the metastable phases is possible, which may result in mechanical and functional degradation in devices. Bl ö chl, P.E., 1994. Projector Augmented-Wave Method. Physical Review B 50, 17953-17979. Černý , M. , Řehák , P., Umeno, Y., Pokluda, J., 2013. Stability and Strength of Covalent Crystals under Uniaxial and Triaxial Loading from First Principles. Journal of Physics: Condensed Matter 25, 035401. Jones, E.A., Wang, F., Costinett, D., 2016. Review of Commercial GaN Power Devices and GaN-Based Converter Design Challenges. IEEE Journal of Emerging and Selected Topics in Power Electronics 4, 707-719. Kohn, W., Sham, L.J., 1965. Self-Consistent Equations Including Exchange and Correlation Effects. Physical Review 140, A1133-A1137. K resse, G., Furthmüller, J ., 1996A. Efficiency of Ab-Initio Total Energy Calculations for Metals and Semiconductors Using a Plane-Wave Basis Set. Computational Materials Science 6, 15-50. K resse, G., Furthmüller, J., 1996 B. Efficient Iterative Schemes for Ab Initio Total-Energy Calculations Using a Plane-Wave Basis Set. Physical Review B 54, 11169-11185. Kresse, G., Hafner, J., 1993. Ab Initio Molecular Dynamics for Liquid Metals. Physical Review B 47, 558-561. Kresse, G., Joubert, D., 1999. From Ultrasoft Pseudopotentials to the Projector Augmented-Wave Method. Physical Review B 59 1758-1775. Ogata, S., Li, J., Hirosaki, N., Shibutani, Y., Yip, S., 2004. Ideal Shear Strain of Metals and Ceramics. Physical Review B 70, 104104. Perdew, J.P., Burke, K., Ernzerhof, M., 1996. Generalized Gradient Approximation Made Simple. Physical Review Letters 77, 3865-3868. Sarasamak, K., Kulkarni, A.J., Zhou, M., Limpijumnong, S., 2008. Stability of Wurtzite, Unbuckled Wurtzite, and Rocksalt Phases of SiC, GaN, InN, ZnO, and CdSe under Loading of Different Triaxialities. Physical Review B 77, 024104. Skowronski, M., Ha, S., 2006. Degradation of Hexagonal Silicon-Carbide-Based Bipolar Devices. Journal of Applied Physics 99, 011101. Udrea, F., Deboy G., Fujihira, T., 2017. Superjunction Power Devices, History, Development and Future Prospects. IEEE Transactions on Electron Devices 64, 713-727. Umeno, Y., Černý , M., 2008. Effect of Normal Stress on the Ideal Shear Strength in Covalent Crystals. Physical Review B 77, 100101(R). Umeno, Y., Kubo, A., Nagao, S., 2015. Density Functional Theory Calculation of Ideal Strength of SiC and GaN: Effect of Multi-Axial Stress. Computational Materials Science 109, 105-110. Umeno, Y., Shiihara, Y., Yoshikawa, N., 2011. Ideal Shear Strength under Compression and Tension in C, Si, Ge, and cubic SiC: an Ab Initio Density Functional Theory Study. Journal of Physics: Condensed Matter 23, 385401. References