Colloquium: Guangfu Luo
ABSTRACT: Accurate control over the growth and defects of functional materials at the atomic level is a major goal of materials science. However, such control is usually difficult to obtain even with state-of-the-art experimental methods. In this talk, I will demonstrate that highly accurate ab initio computations can significantly alleviate this challenge by uncovering the atomic-level mechanisms and providing rationally-revised synthesis routes. I will first present our discovery of dynamic swapping mechanisms that prevail in the growth of both Ruddlesden-Popper oxides  and GaAsBi alloys . Understanding of these critical growth mechanisms has helped us gain more control in the growth of these two classes of materials. Next, I will present our findings on the defects that seriously jeopardize the electronic and optical properties of GaAsBi alloys . This study provides valuable guidance on how to reduce the defects in GaAsBi alloys, which have inhibited their successful applications for years. Finally, I will briefly discuss our surprising discovery of a long-standing issue in the simulation of transition states. This discovery was inspired by the defect study  and is expected to influence the theoretical prediction of dynamics in a number of fields.
 J. H. Lee*, G. Luo*, I. C. Tung, S. H. Chang, Z. Luo, M. Malshe, M. Gadre, A. Bhattacharya, S. M. Nakhmanson, J. A. Eastman, H. Hong, J. Jellinek, D. Morgan, D. D. Fong, and J. W. Freeland, “Dynamic layer rearrangement during growth of layered oxide films by molecular beam epitaxy”, Nature Materials 13, 879 (2014). *equal contribution
 G. Luo, S. Yang, J. Li, M. Arjmand, I. Szlufarska, A. S. Brown, T. F. Kuech, D. Morgan, “First-principles studies on molecular beam epitaxy growth of GaAs1-xBix”, Physical Review B 92, 035415 (2015).
G. Luo, S. Yang, G. Jenness, Z. Song, T. F. Kuech, D. Morgan, "Understanding and reducing deleterious defects in the metastable alloy GaAsBi", NPG Asia Materials, 9, e345 (2017).