Photoluminescence and photocurrent in porous silicon Schottky barriers

Photoluminescence and Raman scattering investigations were performed on porous silicon (PSi) films prepared using different electrochemical etching regimes with the aim of obtaining PSi layers with a variation of Si nanocrystallite sizes. Then Schottky barriers were formed using aluminium contact on a porous surface. Schottky diodes were completed by adding aluminium ohmic contacts to the rear side of the p-type silicon substrate. Current voltage characteristics of the Schottky barriers have been investigated in the dark and under light exposition and photocurrent spectra have been obtained. It is shown that some optimal electrochemical etching regime exists (at etching current density of 5 mA/cm2) which allows the preparation of PSi with a small density of surface defects and best diode parameters. Moreover, our results show that it is possible to change the photocurrent spectrum of Schottky diodes based on PSi by the variation of Si nanocrystallite sizes.