Tunable far infrared semiconductor sources

The concept of continuously tunable far infrared sources was investigated in magnetically and electrically tunable level systems. Landau emission has been investigated in several semiconductors. A useful source for spectroscopic investigations based on bulk GaAs with a resolution below 1 per cm has been developed in the spectral range from 20 to 120 per cm. New promising concepts for tunable sources have been demonstrated recently: A significant line narrowing of the Landau emission was observed from InSb under the presence of hydrostatic pressure above 8 kbar. For the first time tunable emission from spin-flip transitions in uniaxially stressed InSb was observed. Linewidths in the order of 0.2 per cm are found which opens the potential for high resolution spectroscopy with magnetically tunable sources. For the realization of voltage tunable sources based on the voltage tunable electron density in MOS-devices, three possible mechanisms were investigated: The radiative recombination between electric subbands, between minigaps induced by tilted interfaces in respect to the main crystallographic directions and the radiative decay of two dimensional plasma oscillations via periodic grating structures.