Cutting silicon blocks into thin wafers for solar cells and other applications generates a lot of wasted metal because of the width and vibration of the mechanical sawing wire typically used. Sungho Jin at the University of California, San Diego, and his colleagues report a way to etch silicon into various intricate shapes that produces an order of magnitude less waste than conventional approaches.

Credit: AM. CHEM. SOC.

The authors adapted a common etching technique, depositing a catalytic gold and iron layer on top of certain sections of a silicon wafer and using other chemicals to dissolve those parts of the silicon away. Strong neodymium magnets guide the chemical etching, allowing the researchers to slice silicon in any desired direction, forming sheets, microneedles, nanowires (pictured) and tunnels. Magnetically guided chemical etching makes thinner cuts than mechanical sawing, thus reducing waste.

Nano Lett. 10.1021/nl300141k (2012)