Double-Sided Mesoporous Silicon with Embedded Quasi-Regular Arranged Ferromagnetic Nanostructures Fabricated by Electrodeposition

Abstract

Porous silicon matrices fabricated by wet etching are used as template for the deposition of metal nanostructures. The anodization of the silicon wafer is performed on one or on both sides in employing a double-tank electrolytic cell. The resulting porous layers are subsequently filled with a ferromagnetic metal by electrodeposition. In case of double-sided samples an alternating pulsed current is applied. These two processes are extended to ultrathin samples with an entire thickness of about 60 µm. The morphology of the porous structure exhibits average porediameters of 60 nm, a mean pore-spacing of 45 nm and a porelength of 40 µm. Ferromagnetic metals are electrochemically deposited as nanostructures with a specific distribution within the pores.

Filling of porous silicon with magnetic materials

“…The deposition of magnetic metals is carried out preferentially by electrodeposition [41] and often in using a pulsed current to facilitate the pore-filling down to the pore tips [42]. Depending on the chosen metal, the deposition parameters such as current density and current pulse duration have to be determined to achieve desired fillings of the pores.…”

Investigation of Ni and Co Deposition into Porous Silicon and the Influence of the Electrochemical Parameters on the Physical Properties

“…A variation of the pulse frequencies and the current density leads to modifications of the geometry and spatial distribution of the metal deposits within the pores (6). A decrease of the pulse duration from 40 s to 5 s and keeping the current density constant at 15 mA/cm 2 , leads to an increase of the elongation of the Ni-structures (spherical particles of about 50 nm in diameter up to wire-like structures of a few micrometers in length) (7). A variation of the current density between 10 mA/cm 2 and 50 mA/cm 2 influences mainly the spatial distribution of the deposits leading to surface near agglomeration of the structures, filling up to 2/3 of the porous silicon layer and homogeneous distribution of the structures over the entire layer, respectively (8).…”