Observation of periodical negative differential conductivity in nanocrystalline silicon/crystalline silicon heterostructures

We report the observation of periodical negative differential conductivity (NDC) in hydrogenated nanocrystalline silicon/crystalline silicon diode heterostructures by low-temperature current–voltage measurements. The NDC-related series of spike-like current peaks is found to result from the accumulation and depletion of electrons tunnelling through the nanodot layers in the neutral region. The observation has been further supported by the facts of onset-voltage blueshift, number variation in current peaks, and inter-Landau-level tunnelling in the temperature- and magnetic field-dependent experiments. We also discuss the differences between the present periodical NDC and the electric field domain in superlattice structures.