Electric and photoelectric properties of diode structures in porous silicon

Abstract

Diode properties of structures containing a porous silicon layer have been investigated. The structures have been fabricated by depositing metal or indium-tin-oxide layers either directly on the ‘‘as-anodized’’ silicon wafer or on the wafers with upper, nanocrystalline part of the porous layer removed. Different behavior was observed in both cases: (1) The photovoltaic effect is absent in diodes from as-anodized wafers but appears in diodes from the cleaned wafers; (2) the diode ideality factor is close to 2 for ‘‘cleaned’’ diodes and increases in diodes containing an upper porous silicon layer. Energy-band diagrams for the structures are proposed and it is concluded that the electrical transport in those structures is limited by the carrier recombination in the depletion layer.