Universal dynamics during and after ultrafast laser-induced semiconductor-to-metal transitions

We observe common features in semiconductor-to-metal transitions induced by femtosecond laser pulses in crystalline GaAs, amorphous GaAs, and Sb-rich films of amorphous GeSb, by tracking ultrafast changes in the spectral dielectric function. The dielectric function of the metal-like state reveals a decay in the plasma frequency with time after the transition. In addition, the plasma frequency roughly decreases with increasing excitation fluence.