Imaging photoinduced structural dynamics preceding color center creation in silicon carbide

Deterministic creation of defect-based spin qubits in Silicon Carbide (SiC) is crucial for its integration into future quantum and microelectronics technology. Femtosecond laser pulses can create color centers with high probability through nonlinear optical processes, but the lack of a direct structural probe limits our understanding of the lattice deformation mechanism during laser excitation. In this work, the laser fluence is tuned below the threshold of permanent color center creation to explore reversible structural dynamics in 4H-SiC. Time-resolved X-ray nanodiffraction imaging revealed a significant increase in diffraction intensity, attributed to the heterogeneous lattice responses, including strain wave propagation and transient nanocluster formation. The intensity relaxation depends on the diffraction condition, with slower relaxation observed on nanosecond time scales when moving away from the Bragg condition, indicating that these nanoclusters of structural deformation are long-lived precursors to permanent defect creation. A spatiotemporal mapping of the sample surface further reveals the spatial separation of the strain wave that propagates into the sample and the nanoclusters that are stationary close to the surface. Our findings offer crucial insights into lattice dynamics preceding color center creation.