Microstructure of Porous silicon and its evolution with temperature

Hérino, R.; Pério, A.; Barla, K.; Bomchil, G.

doi:10.1016/0167-577x(84)90086-7

Cited by 122 publications

(43 citation statements)

References 8 publications

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“…Initially, the DIOS surface is characterized as a porous surface with 20 -100 nm pore size (Figure 2a; no laser irradiation). Similar to the reported literature [13], surface melting was observed upon laser irradiation: one pulse of 15 mJ/cm 2 -pulse results in significant surface restructuring (Figure 2b) as characterized by an increase in surface roughness and pore size. The estimated surface area reduction is roughly 30% relative to the original DIOS surface by measuring the porous density in the SEM images.…”

Section: Laser Intensity Surface Restructuring and Dios Activitysupporting

confidence: 72%

“…This high surface area significantly lowers the melting point of silicon; pore coalescence and structural collapse were observed at 900°C [13], whereas bulk silicon melting occurs at 1410°C [14]. The driving force for this melting process is a reduction in surface energy of the porous silicon (0.2 J/cm 2 for porous silicon versus 0.0001 J/cm 2 planar silicon) [13]. In fact, the typical nitrogen laser energy (15 mJ/cm 2 -pulse) commonly used in DIOS is known to induce melting of porous silicon [15].…”

mentioning

confidence: 99%

“…Porous silicon can have a surface area a million times greater than that of a planar surface (Ͼ100 m 2 /cm 2 of etched material). This high surface area significantly lowers the melting point of silicon; pore coalescence and structural collapse were observed at 900°C [13], whereas bulk silicon melting occurs at 1410°C [14]. The driving force for this melting process is a reduction in surface energy of the porous silicon (0.2 J/cm 2 for porous silicon versus 0.0001 J/cm 2 planar silicon) [13].…”

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confidence: 99%

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High surface area of porous silicon drives desorption of intact molecules

Northen

Woo

Northen

et al. 2007

J. Am. Soc. Mass Spectrom.

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The surface structure of porous silicon used in desorption/ionization on porous silicon (DIOS) mass analysis is known to play a primary role in the desorption/ionization (D/I) process. In this study, mass spectrometry and scanning electron microscopy (SEM) are used to examine the correlation between intact ion generation with surface ablation and surface morphology. The DIOS process is found to be highly laser energy dependent and correlates directly with the appearance of surface ions (Si n ϩ and OSiH ϩ ). A threshold laser energy for DIOS is observed (10 mJ/cm 2 ), which supports that DIOS is driven by surface restructuring and is not a strictly thermal process. In addition, three DIOS regimes are observed that correspond to surface restructuring and melting. These results suggest that higher surface area silicon substrates may enhance DIOS performance. A recent example that fits into this mechanism is the surface of silicon nanowires, which has a high surface energy and concomitantly requires lower laser energy for analyte desorption. (J Am Soc Mass Spectrom 2007, 18, 1945-1949

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Section: Laser Intensity Surface Restructuring and Dios Activitysupporting

confidence: 72%

mentioning

confidence: 99%

mentioning

confidence: 99%

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High surface area of porous silicon drives desorption of intact molecules

Northen

Woo

Northen

et al. 2007

J. Am. Soc. Mass Spectrom.

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“…Increased temperature also increases the extent of oxidation leading to completely oxidized PSi at around 900-1000 • C [43]. Due to the structural expansion, the pore diameter and porosity are dependent on the extent of oxidation, and a drastic drop in the specific surface area has been observed in PSi oxidized above 600 • C. This could be partly avoided by pre-oxidizing PSi first around 300 • C prior to high temperature oxidation [60].…”

Section: Oxidation Of Psimentioning

confidence: 97%

Fabrication and chemical surface modification of mesoporous silicon for biomedical applications

Salonen

Lehto

2008

Chemical Engineering Journal

154

101

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“…Monocrystalline silicon pressure sensor membranes have been previously formed in most cases by anisotropic etching with an electrochemical etch-stop [6]. High-quality monocrystalline silicon membranes are produced using the APSM process using the following process sequence: (a) anodic etching of porous silicon in concentrated hydrofluoric (HF) acid, (b) sintering of porous silicon at temperatures in excess of 400 C in a non-oxidizing environment [7], and (c) subsequent epitaxial growth using the underlying rearranged porous silicon as a single-crystal seed-layer.…”

Section: Surface Micromachiningmentioning

confidence: 99%

MEMS (Micro-Electro-Mechanical Systems) for Automotive and Consumer Electronics

Marek

Gomez

2011

The Frontiers Collection

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MEMS sensors gained over the last two decades an impressive width of applications:(a) ESP: A car is skidding and stabilizes itself without driver intervention (b) Free-fall detection: A laptop falls to the floor and protects the hard drive by parking the read/write drive head automatically before impact. (c) Airbag: An airbag fires before the driver/occupant involved in an impending automotive crash impacts the steering wheel, thereby significantly reducing physical injury risk.MEMS sensors are sensing the environmental conditions and are giving input to electronic control systems. These crucial MEMS sensors are making system reactions to human needs more intelligent, precise, and at much faster reaction rates than humanly possible.Important prerequisites for the success of sensors are their size, functionality, power consumption, and costs. This technical progress in sensor development is realized by micro-machining. The development of these processes was the breakthrough to industrial mass-production for micro-electro-mechanical systems (MEMS). Besides leading-edge micromechanical processes, innovative and robust ASIC designs, thorough simulations of the electrical and mechanical behaviour, a deep understanding of the interactions (mainly over temperature and lifetime) of the package and the mechanical structures are needed. This was achieved over the last 20 years by intense and successful development activities combined with the experience of volume production of billions of sensors.This chapter gives an overview of current MEMS technology, its applications and the market share. The MEMS processes are described, and the challenges of MEMS, compared to standard IC fabrication, are discussed. The evolution of

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Microstructure of Porous silicon and its evolution with temperature

Cited by 122 publications

References 8 publications

High surface area of porous silicon drives desorption of intact molecules

High surface area of porous silicon drives desorption of intact molecules

Fabrication and chemical surface modification of mesoporous silicon for biomedical applications

MEMS (Micro-Electro-Mechanical Systems) for Automotive and Consumer Electronics

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