Porous silicon composition

In the previous chapter, two examples of multifunetional drag delivery systems applying PSi luminescent and photonic properties were described, but there are many other possibilities to include additional functionalities to the delivery systems. One of the most studied applications is PSi-poljuner composite structures in which PSi have a dual role as a hydroxyapatite growth activator and drag carrier (Mukheijee et al. 2006 Fan et al. 2009, 2011). The composite structures are described in detail in chapter Poljnner-Porous Silicon Composites. ... 

Becker CR, Apperson S, Morris CJ, Gangopadhyay S, Currano LJ, Churaman WA, Stoldt CR (2011) Galvanic porous silicon composites for high-velocity nanoenergetics. Nano Lett 11 803-807... 

Clearly, like Young s modulus, hardness decreases rapidly with increasing porosity. Polymer-porous silicon composites (see handbook chapters Porous Silicon-Polymer Composites and Porous Silicon and Conductive Polymer Nanostructures via Templating ) are likely to have very low hardness but potentially high fracture toughness (see next section). 

Very little data exists on the fracture toughness of porous silicon. However two studies suggest that optimized nanocomposites (see hand book chapter Polymer-Porous Silicon Composites ) could exhibit much higher toughness than nonporous silicon. An experimental study reported that the inclusion of poly-phenylene vinylene polymers into oxidized mesoporous silicon could yield toughness values more than five times higher than that of their bulk silicon control (Ni et al 2005). The maximum value reported for a polymer-impregnated mesoporous film on a wafer was 4.2 MPa. 

Nakamura T, Adachi S (2012) Properties of magnetic nickel/porous silicon composite powders. AIP Adv 2 32167... 

Representative t) es of such composites are illustrated in Fig. 2. Handbook ehapter Polymer-Porous Silicon Composites reviews the different fabrication strategies available. 

Nakamura T, Tiwari BP, Adachi S (2011) Direct synthesis and enhanced catalytic activities of platinum and porous-silicon composites by metal-assisted chemical etching. Jpn J Appl Phys 50 081301... 

Chirvony VS, Bolotin VL, Ovejero J, Matveeva ES, Dzhagarov BM, Albella J, Parkhutik VP (2007) Luminescence properties of the porphyrin/porous silicon composites. Phys Stat Sol (a) 204(5) 1523-1527. doi 10.1002/pssa.200674414... 

Nguyen, T.P., Le Rendu, P., Lakehal, M.. Joubert, P., and Destruel, P. (2000) Poly(p-phen ene vinylene)/porous silicon composites. Materials Science Technology B, 69-70,177-181. 

Einset, E.O. (1996) Capillary Infiltration Rate into Porous Media with Application of Silicon Composite Processing. J. Am. Ceram. Soc., 79(2), 333-338. 

In addition to dense monolithic ceramics, porous silicon nitrides are gaining more importance in technological applications [24], Some porous silicon nitrides with high specific surface area have already been applied as catalysis supports, hot gas filters and biomaterials [25], There is an emerging tendency to facilitate silicon nitride as biomaterial, because of specific mechanical properties that are important for medical applications [25], Moreover, in a recent study it was shown that silicon nitride is a non-toxic, biocompatible ceramic which has the ability to propagate human bone cells in vitro [25], Bioglass and silicon nitride composites have already been realized to combine... 

This chapter concentrates on the results of DS study of the structure, dynamics, and macroscopic behavior of complex materials. First, we present an introduction to the basic concepts of dielectric polarization in static and time-dependent fields, before the dielectric spectroscopy technique itself is reviewed for both frequency and time domains. This part has three sections, namely, broadband dielectric spectroscopy, time-domain dielectric spectroscopy, and a section where different aspects of data treatment and fitting routines are discussed in detail. Then, some examples of dielectric responses observed in various disordered materials are presented. Finally, we will consider the experimental evidence of non-Debye dielectric responses in several complex disordered systems such as microemulsions, porous glasses, porous silicon, H-bonding liquids, aqueous solutions of polymers, and composite materials. 

Figure 1. Effect of magnetic field on the modification of chemical composition of porous silicon during its ageing in air.

A characterization of copper/porous silicon (Cu/PS) nanocomposites fomied by an immersion displacement method is presented. Morphology and structural properties of Cu-PS samples were analyzed using SEM and XRD techniques. The SEM study demonstrates the complicated structure of the Cu/PS samples. The XRD study confirms that deposited Cu is polycrystalline. Copper deposition time has a strong influence on Cu crystal size and the Cu/PS composition. 

L. Monastryrskii, T. Lesiv, and I. Olenych, Composition and properties of thin films on porous silicon... 

Beyond the motivation to fabricate working systems from functionalized porous silicon, there is also more fundamental interest in the reactions of its surfaces. Because the vast surface of nanocrystalline silicon contains a large fraction of the total atoms, the composition and environment of the silicon interface are believed to affect greatly the physical, chemical, and electronic properties of the material. In particular, functionalization of porous silicon with certain organic groups is known to diminish photoluminescence [27] however, the mechanism of quenching has... 

Fig. 4 [7, 8], At anodic potentials near J the electrode behavior is characterized by an exponential dependence of current on potential and by the uneven dissolution of silicon surface leading to the formation of porous silicon (PS) [9]. The values of the characteristic currents J to J4 are a function of electrolyte composition but are largely independent of doping. At potentials more positive than the second plateau current J4, current oscillation may occur [8]. The surface resulting from dissolution at potentials higher than the second peak is brightly smooth, while that produced between the first and second peak is relatively less smooth [10].

A thermodynamic and experimental approach of silicon carbide CVD, application to the CVD-infiltration of porous carbon composites, Christin, Naslain and Bernard, 1979 [125]... 

Christin F, Naslain R, Bernard C (1979) A thermodynamic and experimental approach of silicon carbide CVD. Application to the CVD-infiltration of porous carbon composites. In Sedgwick TO, Lydtin H (eds) Proceedings of the 7th international conference on chemical vapour deposition. Electrochemical Society, Pennington, NJ, pp499-514... 

XANES and USXES data were used to determine phase composition of surface layers and energy level diagram in porous silicon. Porous silicon consists of Si microcrystals covered with amorphous silicon and silicon oxides. 

PHYSICS, CHEMISTRY AND APPLICATION OF NANOSTRUCTURES, 2003 COMPOSITE NANOSTRUCTURES BASED ON POROUS SILICON HOST... 

In this paper we review different technological aspects of porous silicon (PS) utilization as a host material for the fabrication of composite nanostructures. Different types of PS host filling materials and final treatments (annealing, oxidation, and others) are analyzed. 

Fig. 6. 18 Examples of IR spectra in the presence of a composite layer on a silicon electrode. (a) Porous-silicon layer in 15% HF aqueous solution [107] and (b) discontinuous metal deposit (Ag deposited in 0.1 M EDTA (pH 4)-1-0.01 M AgNOj) [109]. In both...

The present paper discusses the preparation and properties of high surface area silicon carbide and oxynitride with respect to possible application in catalysis. The synthetic work includes new routes to high surface area forms of these materials. Regarding properties, an important aspect is stability. This refers both to the stability of a pore system in a non-oxide material, on which there is very little information available, and to the stability of the surface composition in the case of the latter, oxidation to the oxide will be thermodynamically preferred in most cases. We report data on the textural stability of porous silicon carbide and on the surface stability of high surface area silicon oxynitrides. Some of the work reported in the present paper has been described at recent conferences (7,8) and in a communication (9). 

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