ELECTRON VELOCITY OVERSHOOT AND NONEQUILIBRIUM PHONONS IN A GAAS-BASED P-I-N NANOSTRUCTURE STUDIED BY TRANSIENT SUBPICOSECOND RAMAN-SPECTROSCOPY

Transient subpicosecond Raman spectroscopy has been used to study elec tron velocity overshoot as well as nonequilibrium phonons in a GaAs-ba sed p-i-n nanostructure under the application of high electric fields. Both electron distribution functions and nonequilibrium phonon popula tions were directly obtained in the velocity overshoot regime for a va riety of electric field intensities and for different electron densiti es. All of our experimental results are compared with ensemble Monte C arlo calculations and good agreement is achieved.