Impurity-breakdown-induced current filamentation in a dipolar electric field

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Abstract
Filamentary current flow has been investigated in an epitaxial n-type GaAs layer with two Ohmic point contacts. A scanning laser microscope technique has revealed two characteristic regimes of filamentary structure: a large-area filament typical at higher sample currents, and a bendable filament arising at low currents and becoming curved in perpendicular magnetic fields. Self-organization is supposed to be significant upon forming the bendable filament, whereas the large-area filamentary structure is predominantly formed by the electric field distribution due to the point contact geometry. Numerical simulations have been carried out in the second case, showing a good agreement with experimental results.