The spectra of spontaneous terahertz (THz) electroluminescence at the breakdown of shallow Ga acceptor in Ge were observed for the first time and investigated. We found and characterized the emission lines corresponding to the hole transitions between the excited states and the ground state of the impurity center as well as the transitions of the hot holes from the valence band to the impurity and within the valence band. A high quantum yield of the radiative transitions will become an important factor in designing electrically pumped THz emitters for the≈2 THz spectral range.
We report on the first principle calculations of photocarriers kinetics in a photoconductive antenna excited by an ultrashort optical laser pulse. The solution of non-equilibrium Boltzmann equation is used to derive the expression for the irradiated electric field. The analysis reveals the important role of non-uniform photocarrier distribution inside the active layer in the formation of the terahertz radiation from the emitter in both collinear and anti-collinear directions.
We report on polarization spectra of spontaneous terahertz electroluminescence from uniaxially deformed Ge(Ga). At compressive pressure of about 3±0.3 kbar in the [111] direction, near the impurity breakdown threshold, the linear polarization degree attains ≈80-90% for the main lines of the terahertz emission.
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