Electron-density stratification in two-dimensional structures tuned by an electric field

We describe a kinetic instability mechanism which leads to electron-density stratification. The spatial period of the arising space-charge and field configuration is found to be inversely proportional to the electric field and can be tuned by applied voltage. The instability has no interpretation in the framework of a traditional hydrodynamic approach, since it arises from the modulation of the electron distribution function in both the coordinate and energy space. The phenomenon can be observed in two-dimensional nanostructures at relatively low electron densities.