WANNIER-STARK RESONANCES UNDER STRONG LOCALIZATION CONDITIONS IN NATURAL SILICON-CARBIDE SUPERLATTICES

A detailed experimental investigation is made of the electronic transp ort under conditions of Wannier-Stark localization of carriers in a na tural superlattice of hexagonal polytypes of silicon carbide. The 4H a nd 6H polytypes, which possess different superlattice and miniband spe ctrum parameters, are employed. Direct measurements of the electronic current versus the average electric field in the active region of the sample revealed a series of regions of negative differential conductiv ity in fields ranging from 500 to 2100 kV/cm. Analysis of the results shows that the observed current resonances are associated with the dev elopment of the Wannier-Stark quantization process and are due to cond uction mechanisms such as hopping conduction, induced between tile lev els of a Wannier-Stark ladder by a resonant electron-phonon interactio n, and the resonant interminiband tunneling from the first into the se cond miniband. (C) 1996 American Institute of Physics.