Synthesis and Magnetic Characterization of Metal-filled Double-sided Porous Silicon Samples

Abstract

A magnetic semiconductor/metal nanocomposite with a nanostructured silicon wafer as base material and incorporated metallic nanostructures (Ni, Co, NiCo) is fabricated in two electrochemical steps. First, the silicon template is anodized in an HF-electrolyte to obtain a porous structure with oriented pores grown perpendicular to the surface. This etching procedure is carried out either in forming a sample with a single porous layer on one side or in producing a double-sided specimen with a porous layer on each side. Second, this matrix is used for deposition of transition metals as Ni, Co or an alloy of these. The achieved hybrid material with incorporated Ni- and Co-nanostructures within one sample is investigated magnetically. The obtained results are compared with the ones gained from samples containing a single metal.

Magnetically interacting low dimensional Ni-nanostructures within porous silicon

“…In the case of Ni-deposition the so called Watts electrolyte (NiCl 2 , NiSO 4 ) with boric acid as buffer is used. A variation of the pulse frequencies and the current density leads to modifications of the geometry and spatial distribution within the pores of the metal deposits [10] . Magnetic measurements are carried out by SQUID-magnetometry (SQUID magnetometer Cryogenics) up to a magnetic field of 6 T and in a temperature range between 4 and 250 K. The structure and composition of the nanocomposite is investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).…”

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

“…The pulsed current is applied to suppress the exhaustion of the electrolyte along the pore-length and to guarantee that the metal ions can reach the porebottom. 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).…”

Magnetic Nanoparticles Embedded in a Silicon Matrix

“…Typically a solution of 45 g/L NiCl 2 , 300 g/L NiSO 4 and 45 g/L H 3 BO 3 is used. 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 [ 25 ]. A decrease of the pulse duration from from 40 s to 5 s and keeping the current density constant at 25 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) [ 26 ] which is summarized in Table 1 .…”