Tunable colour emission from patterned porous silicon using ion beam writing

Combined ion beam irradiation and electrochemical etching of silicon has been used to pattern light emitting porous silicon. A highly focused beam of helium ions is made to scan across a 4 Ω cm resistivity silicon in a predefined manner. As the ion beam penetrates the sample, it induces lattice damage and increases the local resistivity of the material. This slows down the rate of porous silicon formation, so that a thinner porous layer is formed at the irradiated regions. In this work, the photoluminescence properties of the irradiated porous silicon are studied as a function of dose. The porous silicon is then removed to reveal the underlying irradiated structure. The decrease in thickness of porous silicon with dose is correlated with the observed change in photoluminescence properties.