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 50μm, 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.

The track nanotechnology

“…Since the work by Canham (Canham, 1990;Canham et al,;Gullis and Canham, 1995) demonstrated visible light photoluminescence from PS, much effort has been focused on the possibility of producing optoelectronic devices using this new material by enhancing the photo response of metal-oxide-semiconductor photodetectors (vis/IR) with nanocrystals embedded in the oxide layer (Shieh et al, 2007). The same can be done by using PS in sensors, in the production of visible electroluminescent diodes (Cho et al, 2005) and the application of porous silicon in magnetic sensors (Granitzer et al, 2006). All the above mentioned applications can be modified and improved by using metals or semiconductor nanocrystals of II-VI compounds or metal oxide nanocrystals (these are preferred due to their biocompatibility and quality of being environmentally friendly).…”

Nanoscale Mapping of Heterogeneous Strain and Defects in Individual Magnetic Nanocrystals

“…At the nanoscale, confinement effects, size variations, strain, defects and shape morphology have been recently shown to play a crucial role in mechanical and magnetic device applications [9][10][11][12][13]. For metallic and magnetic materials such as nickel nanoparticles, extended line defects such as edge and screw dislocations provide an important and universal catalyst-free growth mechanism of quasi Crystals 2020, 10, 658 2 of 14 one-dimensional nanostructures [14]. In FePt nanostructures, thermally activated spin current assisted de-pinning of magnetic domain walls has been controlled with the aid of defects [15].…”

Transient surface photovoltage studies of bare and Ni-filled porous silicon performed in different ambients

“…For example, surface electronic states could be affected by gas species by physisorption, chemisorption, or desorption from the surface [ 4 , 5 ]. On the other hand, filling of PS with magnetic metals [ 6 , 7 ] is of interest due to both the distinct properties of the nanosized deposits and the employment of silicon as the base material, key for integration in microtechnology.…”