AI-Assisted Real-Time Tracking of Subnanometer Strain Relaxation during Heteroepitaxy
Jiayu Chen, Danhao Wang, Md Mehedi Hasan Tanim, Yuyang Chen, Ziyi Wang, Peisen Gao, Yucheng Wei, Tianju Wang, Elena Sung, Graham Baker, Jiangnan Liu, Qing Qu, Kai Sun, Zetian MiAbstract
Understanding strain relaxation during the initial stages of heteroepitaxy is essential for controlling interfacial structure and film quality, yet direct real-time quantification remains difficult. Here, we report on the demonstration of AutoRHEED, an AI-assisted in situ framework for tracking subnanometer strain relaxation during epitaxial growth. The method integrates image quality filtering, autonomous streak identification, and physics-guided geometric calibration to directly extract quantitative in-plane interplanar spacing (d spacing) evolution from raw reflection high-energy electron diffraction (RHEED) videos. We applied the framework to highly lattice-mismatched AlSb/Si(001) growth and demonstrated that AutoRHEED could capture the transient evolution from the initially strained state to full relaxation with monolayer-level sensitivity. Moreover, the in situ-derived relaxation trajectory shows excellent agreement with ex situ HAADF-STEM, confirming its structural fidelity and temporal reliability.