Biodegradable porous silicon barcode nanowires with defined geometry.

Silicon nanowires are of proven importance in diverse fields such as energy production and storage, flexible electronics, and biomedicine due to the unique characteristics emerging from their one-dimensional semiconducting nature and their mechanical properties. Here we report the synthesis of biodegradable porous silicon barcode nanowires by metal assisted electroless etch of single crystal silicon with resistivity ranging from 0.0008 Ω-cm to 10 Ω-cm. We define the geometry of the barcode nanowiresby nanolithography and we characterize their multicolor reflectance and photoluminescence. We develop phase diagrams for the different nanostructures obtained as a function of metal catalyst, H(2)O(2) concentration, ethanol concentration and silicon resistivity, and propose a mechanism that explains these observations. We demonstrate that these nanowires are biodegradable, and their degradation time can be modulated by surface treatments.