Transition from Coherent to Incoherent Superlattices Transport
TECHNISCHE UNIV WIEN (AUSTRIA) INSTITUT FUR FESTKORPERELEKTRONIK
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Ballistic electron transport is used to study the transmittance of GaAsGaAlAs superlattices. In a three terminal transistor type device an energy tunable electron beam is injected via a tunneling barrier into an undoped superlattice. The transmitted current is measured as a function of the injector energy. Resonances in the collector current are observed due to miniband conduction in the GaAsAlGaAs superlattice. By analysing the transfer ratio of superlattices at various bias conditions miniband positions and miniband widths are determined. A significant decrease of the miniband transmission is observed wfth increasing electric field accross the superlattice, which is attributed to the the quenching of coherent transport. For longer superlattices an asymmetry between positive and negative bias is found which is asigned to the transition between coherent and incoherent transport.
- Solid State Physics