Cylindrical pore arrays in silicon with intermediate nano-sizes: A template for nanofabrication and multilayer applications

Impregnation of porous silicon with conducting polymers

“…It is an experimental fact that the applied current density and the type of anodizing solution determine the produced pore size and morphology [2,12]. Figure 1 shows the SEM image of crosssectional (image a) and top (inset: image b) views of the porous layer produced on a heavily doped substrate under the above mentioned conditions.…”

“…The porosity of as-synthesized sample is 52% as estimated from gravimetric measurement. It is worthy noted that the presence of KMnO 4 as an oxidizing agent is necessary for getting such medium pore size [2,13]. Figure 2 shows the current transient (i-t characteristic) obtained during the electropolymerization of pyrrole into PSi matrix at a potential 0.8 V measured versus Pt wire.…”

“…Many trials have been done by different research groups to create efficient electrical contact and to improve the mechanical properties of the material. Most of the studies were directed on utilizing metallic contact through deposition from either liquid [1,2] or vapor phase [3]. Unfortunately, it appears that such approaches lead to poor penetration and/or pore mouth blockage by the metal, especially in case of PSi layers composed of pore sizes < 50 nm.…”

Porous Silicon Formation by Anodization

“…CrO 3 has been used Christophersen et al 2000;Ouyang et al 2005) to produce macroporous silicon, while potassium permanganate (KMnO 4 ) also acts to increase pore size (Ogata et al 2000;Harraz et al 2008). The inclusion of hydrogen peroxide (H 2 O 2 ) has been shown to produce layers with monohydride passivation (Yamani et al 1997), although its role in the formation of layers with wider pores has been the subject of greater interest (Ogata et al 2000;Ge et al 2010).…”

Preparation and characterization of room temperature operating NO<inf>2</inf> gas sensor based on intermediate-sized porous silicon modified with WO<inf>3</inf> thin films

“…In order to achieve not only high-sensitivity detection but also fast response-recovery rate, the PS should combine high specific surface area and large pore opening. Therefore, intermediate-sized PS with pore sizes between 50~200 nm attract a great interest because of its unique microstructure properties provide large special surface area increasing enough adsorption sites and highly ordered conduits accelerating gas diffusion [11]. However, until now, the sensing properties of intermediate-PS based gas sensors have not been investigated intensively and systematically.…”