Photoassisted electrochemical micromachining of silicon in HF electrolytes

Silicon Porosification: State of the Art

“…For porous silicon based Pd catalyzed H 2 sensors, it has been established that (a) the distribution of Pd over the porous skeleton plays a significant role dictating the dynamics of the sensor, 639 and (b) the response time and stability of the sensor are influenced by the complex Pd-H interactions 640 which in turn critically depend on the concentration of binding sites (pores). Mlcak et al 641 established that Pd-doped PSi films show enhanced catalytic activity to hydrogen oxidation into water, which implies an increase of the reaction rate. It was also found that the catalytic activity of Pd-doped porous silicon at 160 • C is significantly higher than that of a planar surface covered with Pd.…”

Redox-Active Monolayers in Mesoporous Silicon

“…58 Si 2p narrow scans of SAM-2 samples (Figure 2d) showed minimal signs of substrate oxidation, with substoichiometric oxides (Si (1) and Si (2) ), such as as oxo bridges 59 between silicon atoms or silanol terminations, 59,60 evident in the 100−102 eV region 61 on the high binding energy side of the Si 2p 1/2 −Si 2p 3/2 spin−orbit split doublet (99.9 and 99.3 eV, respectively). 62 Spectroscopic shifts for the Si 2p region introduced by Si (1) −Si (4) oxides are well-documented. 61,62b The presence of siloxo side products is not unexpected, as the coupling of Si surface radicals (the putative resting state in the radical chain coupling reaction responsible for the desired reaction with the 1-alkyne 25a,27 ) to oxygen traces in the reaction medium is very favorable.…”

“…The voltammetric responses of the Si−CC passivated and CuAAC derivatized PSi electrodes (SAM-2) displayed a satisfactory stability upon prolonged cycling in aqueous environments, with a decrease in Γ of 16 ± 10% after 100 CV cycles (Figure S8 in the Supporting Information). Upon prolonged electrochemical analysis of the PSi electrodes in aqueous environments, the fully oxidized Si (4) state becomes more evident (Figure S8 in the Supporting Information). It is likely that oxo sites are the main cause of further oxidation, 59 as these defects are ubiquitous for "wet" etched Si(100).…”

Structure and Surface Modification of Porous Silicon

“…For PSi-based Pd-catalyzed H 2 sensors, it has been established that (1) the distribution of Pd over the porous skeleton plays a signi fi cant role dictating the dynamics of the sensor (Rahimi et al 2005 ) and (2) the response time and stability of the sensor are in fl uenced by the complex Pd-H interactions (McLellan 1997 ) , which in turn depend critically on the concentration of binding sites (pores). Mlcak et al ( 1994 ) established that Pd-doped PSi fi lms show enhanced catalytic activity to hydrogen oxidation into water, which implies an increase of the reaction rate. It was also found that the catalytic activity of Pd-doped porous silicon at 160 °C is signi fi cantly higher than that of a planar surface covered with Pd.…”