THz Radiation Source Through Periodically Modulated Structures.
Interim rept. no. 6, Mar-May 97,
TECHNISCHE UNIV VIENNA (AUSTRIA) INST FUER FESTKOERPERELEKTRONIK
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In this period the main focus of the work was dedicated to the study of a superlattice under bias. Most of the previous experiments could not investigate the bias dependence of the superlattice current since the applied electric field was not varied in a controlled way. Our structure has the specific advantage that a defined voltage can be applied between base and collector. Therefore our work represents the first defined experiment of superlattice transport as a function of electric field across the superlattice. As a result we find that for negative bias the current is quenched quite rapidly and decreases to zero at the expected value of the localization electric field 5kVcm. For positive bias a very promising behavior is found up to an electric field of 1kVcm a nearly constant current is observed which is an indication for electric field induced miniband transport. This observation which has to be confirmed with several samples, could be the first signature of a Bloch-type current in the superlattice.
- Solid State Physics