Multicolor photoluminescence from porous silicon using focused, high-energy helium ions

Abstract

The ability to controllably red-shift the wavelength of the photoluminescence (PL) from patterned areas of p-type porous silicon over 150 nm in the visible spectrum, was demonstrated. This was achieved by pre-irradiating the silicon with a focused 2 MeV helium-ion-beam, resulting in lattice damage which increases the resistivity and reduces the current flowing. The gradual red-shift of the PL emission with dose is accompanied by an increase in nanocrystal size as a result of lower hole current through the damaged regions. The results show that oxidation-related mechanisms may-redshift the PL emission when thermally or chemically oxidized.