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HL: Fachverband Halbleiterphysik

HL 38: Materials and Devices for Quantum Technology II

HL 38.12: Vortrag

Donnerstag, 12. März 2026, 12:30–12:45, POT/0051

Finding the kinked propagation of the I3 defect in hexagonal silicon using a machine-learned potential — •Jolijn Dellevoet — Eindhoven University of Technology, Eindhoven, The Netherlands

Hexagonal silicon-germanium (hex-SiGe) alloys have recently emerged as promising direct-bandgap semiconductors suitable for on-chip optical communication, offering a path to reduce heat production in microchips. Currently, the hex-SiGe crystal is grown in core-shell nanowire structures, but their crystal quality is hindered by the formation of I3 defects. During growth, these defects nucleate and can propagate into otherwise pristine crystal. This propagation has been observed experimentally but not reproduced in atomistic simulations, leaving the underlying mechanism unclear. This presentation reveals, at atomic resolution, a kinking mechanism that enables the I3 defect boundary to propagate within hex-Si. This mechanism and its corresponding energy landscape are obtained by using the nudged elastic band (NEB) method in combination with the machine-learned PACE potential. Although the calculations are currently limited to Si systems, future studies could focus on extending the calculations to SiGe systems. The temperature and boundary length dependence of the transition rate can ultimately be used to optimize growth conditions of the hex-SiGe core-shell nanowires.

Keywords: Hexagonal silicon; Nudged elastic band; Silicon lasing; Defect theory; Machine-learned potential