In situ monitoring of quantum dot growth using a magnification inferred curvature method

The growth of InAs on a GaAs (001) substrate follows the Stranski–Krastanov (S–K) growth mode. Initially, the stress due to the lattice constant difference is small, resulting in two-dimensional growth. However, as the thickness of the growth layer increases, this stress accumulates, and upon reaching a critical film thickness, the growth transitions to three-dimensional, facilitating stress relaxation. Strain changes during crystal growth can be observed through variations in substrate curvature. However, in InAs/GaAs quantum dots (QDs), these changes are minimal, making observation challenging. Previously, the curvature of the substrate during InAs/GaAs QD formation could only be estimated with low precision, necessitating the use of very thin substrates with cantilever structures to achieve higher curvature. In this study, we applied the magnification inferred curvature (MIC) method, which allows for high-precision estimation of substrate curvature during molecular beam epitaxy growth. This method enabled us to observe strain changes during the formation and relaxation processes of QDs on standard-thickness GaAs (001) substrates. The results highlight the potential of the MIC method in investigating the complex interplay of strain and stress in semiconductor growth processes, emphasizing its suitability for fabricating next-generation QD devices.