Ultrafast processes of highly excited carriers in CdSxSe1-x-doped glass

Femtosecond pump-probe experiments were conducted, and transient absorption spectra showing ultrafast dynamic processes of highly excited carriers were observed in a glass doped with microcrystalline CdSxSe1-x (average particle diameter of 2 nm). A relaxation process with a time constant of about 2 ps was obtained. This was the first observation of a 2-ps dynamic process occurring over a very wide spectral range, and the process can be understood as the relaxation of the excited carriers in the dangling-bond surface states. A residual increment in absorption was evident after the relaxation.