Impact of High-Field Charge Transport on Terahertz Emission From Semiconductor Devices

We present an experimental study that provides insight into the charge carrier dynamics that lead to terahertz (THz) emission. We perform time-resolved THz experiments on semiinsulating GaAs structures with periodically poled surface electrodes. The individual charge carrier dynamics that contribute to the THz emission process are identified by their dependence on the applied field. Electron transport in inhomogeneous fields is found to dominate the emission of THz radiation. Other dynamics that become visible by their specific THz emission are the Dember effect, the intervalley transfer of electrons, and hole currents at high field strengths.