Strong Terahertz-Photocurrent Resonances in Miniband Superlattices at the Bloch Frequency
We have observed resonant changes in the current-voltage characteristics of miniband semiconductor superlattices when the Bloch frequency is resonant with a terahertz field and its harmonics. This corresponds to absorption and gain of THz radiation in the Wannier Stark ladder of the superlattice. The resonant feature consists of a peak in the current which grows with increasing laser intensity accompanied by a decrease of the current at the low bias side. When the intensity is increased further the first peak starts to decrease and a second peak at about twice the voltage of the first peak is observed due to a two-photon resonance. At the highest intensities we observe up to a four-photon resonance.
KeywordsBloch Oscillation Photon Resonance Increase Laser Intensity Terahertz Field Wannier Stark Ladder
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