Real-time electron-ion dynamics for photoinduced reactivation of hydrogen-passivated donors in GaAs

Photoassisted reactivation of H-passivated Si donors in GaAs has been demonstrated by first-principles calculations. In order to examine the survival of the excited state, we have applied our recently developed scheme of the ab initio molecular dynamics coupled with the time-dependent Schrodinger equation for electrons. We have found a possible electronic excitation which significantly lowers the dissociation-barrier height from 1.79 to 0.23 eV. This result explains well the recent experiment of carrier recovery by laser illumination [D. Loridant-Bernard, S. Meziere, M. Constant, N. Dupuy, B. Sombret, and J. Chevallier, Appl. Phys. Lett. 73, 644 (1998)].