The Radiation Source through Periodically Modulated Structures.
Interim rept. no. 4, Sep-Nov 96,
TECHNISCHE UNIV VIENNA (AUSTRIA) INST FUER FESTKOERPERELEKTRONIK
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While the previous period was dedicated to studies of undoped field free GaAsGaAlAs short period superlattices with different well widths, we have concentrated our activities in the 4th period of this project on the study of combinations of different superlattices using an advanced technique of hot electron spectroscopy. The basic idea of this structure is the development of a new injection structure which will allow the realization of an inverted population in a well defined superlattice subband. The semiconductor superlattices under investigation consist of a periodic sequence of alternately grown thin layers of GaAs and AlGaAs. The sophisticated technology of Molecular Beam Epitaxy MBE gives us the possibility to fabricate artificial monocrystalline semiconductors with desirable minibands and minigaps. Once a well defined quantummechanical structure with extremely narrow potential barriers in the order of 10 atomic layers is grown in a controlled manner, the transport of electrons in the structure is largely governed by quantum states. With this structure we are able to demonstrate that injection of carriers in possible in a well defined miniband, transition to a lower state and extraction again through a miniband. This is a key experiment for the generation of THz emission between two minibands. In the next period we will systematically study the transport in a biased miniband of a superlattice.
- Electricity and Magnetism