Subpicosecond Raman studies of electric-field-induced optical phonon instability in an In_0.53Ga_0.47As-based semiconductor nanostructure

Transient carrier transport phenomena in an In_0.53Ga _0.47As-based p-i-n semiconductor nanostructure have been studied by using subpicosecond transient/time-resolved Raman spectroscopy. We observe an instability of the GaAs-like optical phonon population in this nanostructure semiconductor that occurs when electrons are accelerated to very high velocities by the application of intense electric fields. The results open up a new channel for creating coherent THz frequency that can be used in THz electronic devices. We suggest that the observed phenomena will have enormous impact on the carrier dynamics and carrier transport in nanoscale semiconductor electronic devices.