Resumen de Electrical transport phenomena in nanostructured porous-silicon films
M.A. Vásquez-A., G. Romero-Paredes, R. Peña-Sierra
The charge transport mechanisms in nanostructured porous silicon (PS) films were studied through current-voltage (I-V) measurements of planar Au/PS/Au structures in dark conditions at 300 K. The films were formed by electrochemical etching of 1 − 5 Ω-cm p-type Si (100) wafers producing PS layers of 4.48 × 10^(9) Ω-cm. The charge transport is limited both by the space charge limited currents (SCLC) and the carrier trapping- detrapping kinetics in the inherent localized PS energy levels. I-V characteristics evolve according to the trappingdetrapping carrier kinetics in the films showing that applying external bias, the electrical current can be controlled. For the first time the trap filling limiting voltage (V_(TFL)) was identified in PS films that shift between 1 and 3 volts by the carrier trapping-detrapping kinetics from the PS intrinsic defect states. An energy band diagram for the films is schematically depicted including defect states. To give a reasonable explanation of the found behavior the existence of a thin silicon oxide film covering the network-like-silicon-nanocrystallites is required, in agreement with the widely accepted PS film structural models.
