Diffusive Electron-phonon Interaction for Terahertz Radiation

We demonstrate terahertz (THz) electromagnetic wave radiation could induced by interactions between acoustic (AC) phonons and diffusive electrons. AC phonons are generated in thin GaP layer on
$n$
-Si, while THz wave was emitted as AC nanowaves encountered diffusively transporting electrons in the Si layer. The pulse-like emission patterns at
$t=t_{1}$
and
$t_{2}$
were in agreement with the temporal periods of the electron-phonon interactions via two main AC packets originating from GaP/Si and air/GaP interfaces. Additionally, the GaP-thickness-dependent THz amplitude was affected primarily by the density profile of the electron reservoir.