Analyses of Ballistic Electron Transport in Nanocrystalline Porous Silicon

The characteristics of ballistic electron transport in porous silicon (PS) are investigated in terms of the electron emission from PS diodes and the energy distribution of emitted electrons. The energy distributions show a behavior of ballistic electron emission that is quite different with the Maxwellian distribution. This is clearly observed at low temperatures below 150 K where the electrical conduction in PS is dominated by the tunneling mode. At 100 K, the peak position of distribution curve becomes more close to the energy corresponding to the energy gain expected from ballistic transport without any scattering losses. The simulated energy distribution suggests that the electrons having higher energies in a non-equilibrium state travel ballistically in PS via field-induced tunneling process. These results support that electrons can travel ballistically in nanocrystalline layer under a high electric field. The observed ballistic transport indicates the further technological potential of silicon nanocrystallites.