Ferromagnetic Nanostructures Incorporated in Quasi‐One‐Dimensional Porous Silicon Channels Suitable for Magnetic Sensor Applications

Abstract

Mesoporous silicon structures are fabricated during an anodization process of highly doped n‐type silicon in hydrofluoric acid solution. The resulting pores are oriented perpendicular to the surface and exhibit a diameter of about 50 nm and a length up to 50 μm, controlled by the etching time. The growth of the pores is self‐organized and depends on the crystal orientation of the used silicon wafer. The achieved channels, highly oriented along the (100) direction, are filled with nickel in a second electrochemical step. The deposition process leads to a distribution between high aspect ratio Ni‐wires and Ni‐particles of the incorporated metal. This achieved (porous silicon/Ni)‐nanocomposite system exhibits a twofold switching behavior of the magnetization curve at two different field ranges. This property gives rise to high‐magnetic field sensor applications based on a silicon technology.