ULTRAFAST CARRIER DYNAMICS AND INTERVALLEY SCATTERING IN ZNSE

Intraband carrier dynamics were measured in ZnSe films by a two-wavele ngth pump probe technique with 180 fs resolution. A below-band pump pu lse was used to heat carrier distributions in N-type samples by free c arrier absorption. The electron cooling time constant was observed to be 500 fs. Intervalley scattering was seen to play a significant role in the electron dynamics and the scattering time from the L back to th e Gamma valley was measured to be 1.8 ps. By examining the ratio of th e intervalley component to the total response as a function of pump ph oton energy, the bottom of the L valley was determined to lie 1.30 eV above the Gamma-valley minimum. (C) 1997 American Institute of Physics .