The seeds and homogeneous nucleation of photoinduced nonthermal melting in semiconductors due to self-amplified local dynamic instability

Abstract

Laser-induced nonthermal melting in semiconductors has been studied over the last four decades, but the underlying mechanism is still under debate. Here, by utilizing an advanced real-time time-dependent density functional theory simulation, we reveal that the photoexcitation-induced ultrafast nonthermal melting in silicon occurs via homogeneous nucleation with random seeds originating from a self-amplified local dynamic instability at the photoexcited states rather than by simultaneously breaking of all bonds, as suggested by the inertial model, phonon instability, or Coulombic repulsion mechanisms. Due to this local dynamic instability, any initial small random thermal displacements of atoms can be amplified by a charge transfer of photoexcited carriers, which in turn creates a local self-trapping center for the excited carriers and yields the random nucleation seeds. This finding provides fresh insights into photoinduced ultrafast nonthermal melting.

27 pages,8 figures

References in corpus (3)

• Thermal and nonthermal melting of silicon under femtosecond x-ray irradiation
• The critical role of hot carrier cooling in optically excited structural transitions
• Using Diffuse Scattering to Observe X-Ray-Driven Nonthermal Melting

Cited by in corpus (4)

• Full-scale ab initio simulations of laser-driven atomistic dynamics
• The photoinduced hidden metallic phase of monoclinic VO2 driven by local nucleation via a self-amplification process
• Origin of Immediate Damping of Coherent Oscillations in Photoinduced Charge Density Wave Transition
• Picosecond-scale Heterogeneous Melting of Metals at Extreme Non-equilibrium States