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In this chapter, we investigate on indium particles elaboration by different annealing processes: rapid thermal annealing (RTA) and conventional processes. The elaborated particles are dedicated to be used as catalyst for silicon nanowires’ (SiNWs) growth by vapor–liquid–solid (VLS) process. The annealing parameters effect on indium particles properties is studied. After conventional annealing, the indium layer is cracked into elongated and inhomogeneous islands of micrometric sizes. XRD analysis depicts, in addition to pure indium planes, the presence of new peaks attributed to indium oxide (In2O3) planes formed during annealing. After hydrogen treatment with a flow rate of 60 sccm during 10 min, some In2O3 peaks are eliminated and replaced by new indium peaks, explaining the amelioration of indium particles morphology. These formed particles have been used as catalyst for SiNWs’ growth. A low density of SiNWs is obtained, attributed to In2O3 persistence, decreasing the indium catalytic effect. Quasi-spherical and homogeneously distributed indium particles with an average size of 422 nm are successfully grown in one step by the RTA process during short time (5 min) at lower temperature (450°C). XRD analysis shows the absence of indium oxide in the contrary to those formed by the conventional furnace. SiNWs with higher density are obtained, highlighting the harmful role of indium oxide.

Porous silicon (PS) decorated by several nanostructured metal elements has still aroused interests as promising composites in many industrial applications. With the focus mainly on the synthesis, the aspect of stability against optical irradiation of such materials has so far not been thoroughly addressed. This work focuses primarily on the influence of lithium chloride solution (LiCl) treatment on the physical properties of PS. Variations in the structural and optoelectronic properties of PS were observed after immersion in (LiCl), as revealed by the obtained analyses. Moreover, enhanced photoluminescence (PL) property of the PS after passivation by lithium particles was clearly shown, and their presence on the surface of the microporous silicon was confirmed by FTIR spectroscopy and atomic force microscopy. An improvement of the minority carrier lifetime was also obtained, which was attributed to the decrease of the surface recombination velocity after LiCl treatment.

The titanium dioxide (TiO2) purity is very important for the TiO2-based applications making essential the impurities density reduction. In this study, we propose an efficient purification process of TiO2powder in order to reduce impurities. The low-cost proposed approach is based on an iterative gettering (IG) process combining three main steps: (1) a porous TiO2sacrificial layer formation (p-TiO2), (2) a rapid thermal annealing (RTA) of p-TiO2powder in an infrared oven at 950 °C under air permitting the residual impurities diffusion to the porous layer surface and (3) etching in acid solution to remove the porous layer. Effect of the proposed gettering process on purification efficiency was evaluated by different characterization techniques such as the transmission electron microscopy (TEM), the energy dispersive X-ray spectroscopy (EDX), the UV–Visible-NIR spectroscopy, the X-ray diffraction (XRD) and atomic absorption spectroscopy (AAS). The obtained results showed the efficient removal of metal impurities, such as Cu, Al, P, and Fe confirming the efficiency of the process improving the purity from 89% to 99.96%.

This work focuses on the impact of Bismuth (Bi) solution treatment on the optical properties of p-type porous silicon prepared by electrochemical anodization. Bi-layers of variable thickness are incorporated in porous silicon via a dip coating technique. The changes in the structural and optical properties of Bi (III)/PS nanostructures are monitored by Atomic Force Microscopy, Fourier transform infrared measurements and photoluminescence spectroscopy. These analyses highlight a relevant impact of the deposition process, which modifies the intrinsic properties of the porous silicon by the incorporation of Bi (III) in its pores. It is found that ultra-thin films of bismuth oxide formed after a heat treatment in air at 400 °C and deposited on PS samples leads to its stability as well as to passivating its dangling bands. For thicknesses ranging from 6 to 20 nm, the photoluminescence property in the visible region of Bi/PS nanostructures has been improved. This may be of interest for various optoelectronic applications.