Abstract

The tooling rate of hot carriers has been extensively studied in direct-gap crystalline semiconductors such as GaAs. In undoped semiconductors, hot carriers cool by emission of optic phonons with a typical rate of 200 nieV/ps. in disordered semiconductors, this rate could be different because (i) momentum need not be conserved and (ii) the optic phonons can be localized. A measurement of the cooling rate of hot carriers in amorphous semiconductors would provide insight on the influence of disorder on the carriers in the extended states. Until now, this measurement has not been possible because the relaxation of the momentum conservation rule in optical transitions renders useless the spectroscopy of absorption saturation common in femtosecond experiments.²

© 1992 Optical Society of America