Zheng Huang, Tie-Yu Lü, Hui-Qiong Wang, Shuo-Wang Yang, Jin-Cheng Zheng, Electronic and thermoelectric properties of the group-III nitrides (BN, AlN and GaN) atomic sheets under biaxial strains, Computational Materials Science, Volume 130, 2017, Pages 232-241, ISSN 0927-0256, https://doi.org/10.1016/j.commatsci.2017.01.013.
Based on first-principles methods and Boltzmann transport theory, we investigated the biaxial strain effects on electronic and thermoelectric properties of three group-III nitrides (BN, AlN and GaN) 2D honeycomb mono-layered nanosheets. The direct-indirect band gap transitions occurred for BN and GaN nanosheets when the strain was applied. In addition, the band gaps decreased with increase of tensile strain; and we uncovered the mechanism behind by the total and projected density-of-state (PDOS) analyses. At the same time, we presented the contour plots of their electrical transport properties as a function of both temperature and carrier concentration at strain-free states. Power-factors of BN, AlN and GaN nanosheets were also calculated. We found only peak power factors of p-type GaN and n-type BN showed a strong dependence on biaxial strain. Such differences of the strain-dependent thermoelectric performance among BN, AlN and GaN may be due to the competition between covalency and ionicity in these 2D structures. Our results provide a new avenue to optimize thermoelectric properties of 2D nanosheets by strain engineering.
This work is supported by the Fundamental Research Funds for Central Universities (Grant Nos. 20720160020), the Natural Science Foundation of Fujian Province, China (Grant No. 2015J01029), Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund (the second phase),
the National Natural Science Foundation of China (no. U1332105 and 11335006), the specialized research fund for the Doctoral Program of Higher Education (no. 20120121110021), and the National High-tech R&D Program of China (863 Program, No. 2014AA052202).