Self-assembled ErAs islands in GaAs: Growth and subpicosecond carrier dynamics

We report the growth of self-assembled ErAs islands embedded in GaAs by mol ecular beam epitaxy. The nucleation of ErAs on GaAs occurs in an island gro wth mode leading to spontaneous formation of nanometer-sized islands. Sever al layers of ErAs islands separated by GaAs can be stacked on top of each o ther to form a superlattice. X-ray diffraction shows superlattice fringes f rom such samples. Pump-probe measurements indicate carrier capture times as short as 120 fs. These capture times are strongly correlated with the peri od of the superlattice. (C) 1999 American Institute of Physics. [S0003-6951 (99)02848-X].