Femtosecond luminescence from partly redistributed nonequilibrium electrons in InAs

We observe transient behavior of nonequilibrium electrons in photoexcited i ntrinsic InAs, using luminescence up-conversion technique with a time resol ution of about 120 fs. Ranging from Stokes side to even anti-Stokes side, t ime-resolved hot luminescence is measured. Temporal evolution of the lumine scence consists of two components. One is the picosecond component, which i s well fitted by a calculation primarily dealing with electron cooling. The other is the femtosecond component, which can be attributed to partly redi stributed nonequilibrium electrons being in thermalization. [S0163-1829(99) 01411-3].