SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 46: Poster Session IV: Semiconductor substrates II
O 46.1: Poster
Dienstag, 2. März 2021, 13:30–15:30, P
Atomistic Modeling for the Vapor-Phase Growth of GaAs Nanowires: from DFT to Growth Kinetics — •In Won Yeu1, Gyuseung Han1,2, Cheol Seong Hwang2, and Jung-Hae Choi2 — 1Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 02792, Korea — 2Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Korea
Based on density functional theory (DFT), this study introduces an ab initio approach tackling the vapor-phase growth kinetics of III-V nanowire (NW) depending on temperature (T) and pressure (P) conditions. By evaluating the vibrational entropy contribution to the surface energy through surface phonon calculations, the T-P dependent variation in surface reconstructions was successfully predicted by the authors. Considering the surface transitions, the change in Gibbs free energy is calculated as a function of T and P at each growth process on surfaces: adsorption and nucleation. The comparison of the free energy among different surfaces enables us to predict the relative rate of growth depending on crystallographic directions and stacking sequences. As a result, we identify the mechanism of extreme anisotropic growth of GaAs (spontaneous NW formation) along a certain polar direction, <111>B; the preferential adsorption of vapor sources on (111)B surface, allowed at narrow T-P range, induces the unidirectional growth. In addition, the asymmetric formation of stacking sequence during the growth along the two opposite directions of a polar direction, <111>A and <111>B, is elucidated, showing a perfect agreement with experimental observations.