Heat treatment effect on porous silicon

Лабунов, В. А.; Bondarenko, Vitaly; Glinenko, I.; Dorofeev, A. M.; Tabulina, L. V.

doi:10.1016/0040-6090(86)90200-2

Cited by 105 publications

(40 citation statements)

References 14 publications

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“…This is explained as the result of the expanded lattice coefficient for PS, which is free to expand in the out-of-plane direction but is constrained in the in-plane direction. Measured increase in lattice parameter in the out-of-plane direction has been correlated with surface oxidation [55], [56], the presence of Si-H and Si-H termination [57], [58], and absorbed water [57] at the porous surface layer. While PS tends to grow as an epitaxial single crystal [55], the lattice misfit between the interior Si and exterior PS layers causes out-of-plane curvature as in a multilayer composite structure [55].…”

Section: Discussionmentioning

confidence: 99%

Mechanical Effects of Galvanic Corrosion on Structural Polysilicon

Miller

Hughes

Wang

et al. 2007

J. Microelectromech. Syst.

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Abstract-The mechanical properties of miniaturized materials depend strongly on their structure, which can be altered by wet chemistry methods common in microsystems postprocessing. In a comprehensive and systematic study, we examine the dissolution of silicon when immersed in various hydrofluoric acid (HF)-based chemistries. Specifically, the frequency of mechanical resonance f R of microcantilever beams is used as a vehicle to examine the corrosion of polycrystalline silicon (polySi). A decrease in f R that occurs as a function of immersion time in HF was measured for microcantilevers as well as "comb drives" in contact with a noble metal (gold). Time-dependent variation was also observed in the modulus and hardness measured during indentation testing, sometimes with pronounced difference for specimens contacted to gold. Secondary sources of influence, such as in-plane-oriented residual strain (which remained unchanged), through-thickness-oriented residual strain gradient (increased away from the substrate), and electrical resistance (greatly increased) are examined, but were found not to significantly contribute to the decrease in fR of the microcantilevers. Morphological characterization identified attack on the surface along with grain delineation for the polySi, with the formation of a nanoscale porous layer at the near surface. The damage to the microcantilevers can be modeled by approximating the beams as a laminated composite structure. Such analysis suggests that damage, induced as the result of galvanic corrosion, results from the decreased stiffness of the near surface porous silicon (PS) layer as well as a change in the effective thickness of the beams. Last, corrosion damage is compared between eight representative HF-based chemistries. The measurements here suggest that the fabrication and postprocessing of microsystems components are important, because they can greatly influence the material properties, design, performance, lifetime, tribology, manufacture, and required operating environment of microscale and nanoscale devices.[

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Section: Discussionmentioning

confidence: 99%

Mechanical Effects of Galvanic Corrosion on Structural Polysilicon

Miller

Hughes

Wang

et al. 2007

J. Microelectromech. Syst.

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“…The height of the large pores is almost the same size as the pores lying under the large pores, ranging 100~300 nm. This suggests that large pores are grown as a result of dissolution of the small size pores [10]. Some parts of the AlN IL under the pit are found on the internal walls of open large pores.…”

Section: Methodsmentioning

confidence: 98%

Improved MOCVD growth of GaN on Si‐on‐porous‐silicon substrates

Ishikawa

Shimanaka

Amir

et al. 2010

Phys. Status Solidi (c)

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The mechanism of the poor surface morphology of MOCVD‐grown GaN on porous Si (PSi) substrates was explored. Transmission electron microscopy suggests that a vacancy growth of pores starts, which is accompanied by the migration of the top surface of the PSi layer during the initial growth stage of GaN on the AlN inter layer. This causes a lot of pits on top GaN and wavy interface between GaN of the PSi layer, deteriorating the poor surface morphology. The epitaxial Si layer on PSi is effective in suppressing the migration of the top surface of the PSi layer. The GaN film on the epitaxial‐Si/PSi shows a mirror surface with pits‐free and very few cracks. No voids at the interface between the AlN IL and Si/PSi substrate are observed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…Indeed, we found that oxidation at temperatures above 1010 °C caused severe structural changes (see Figure S1, Supporting Information), resulting in a drastic decrease in the thickness and the porosity of the porous layer, and eventually collapse of the nanostructure. [ 60 ] By lowering the oxidation temperature to 1000 °C and extending its duration to 46 h, we achieve complete oxidation of the porous layer and formation of a 850 nm thick planar SiO 2 layer beneath the oxidized porous nanostructure, while preserving the delicate nanostructure of the porous layer. These characteristics can be seen in Figure 2 c, presenting a crosssectional backscattered electron micrograph of the PSiO 2 fi lm, which provides elemental composition contrast.…”

Section: Fabrication and Functionalization Of Oxidized Psimentioning

confidence: 99%

“…[ 55 ] Conventional thermal oxidization of PSi is carried out at 500-900 °C for durations of several minutes to an hour, [ 11,52,[56][57][58][59] primarily to improve the nanostructure stability in aqueous media. Oxidation at temperatures higher than 1000 °C leads to structural deterioration of the porous layer, accompanied by drastic decrease in the surface area and transition of the elongated columns into closed sphere-like pores; [60][61][62] thus unsuitable for biosensing applications. Indeed, we found that oxidation at temperatures above 1010 °C caused severe structural changes (see Figure S1, Supporting Information), resulting in a drastic decrease in the thickness and the porosity of the porous layer, and eventually collapse of the nanostructure.…”

Section: Fabrication and Functionalization Of Oxidized Psimentioning

confidence: 99%

Oxidized Porous Silicon Nanostructures Enabling Electrokinetic Transport for Enhanced DNA Detection

Vilensky

Bercovici

Segal

2015

Adv Funct Materials

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Nanostructured porous silicon (PSi) is a promising material for the label-free detection of biomolecules, but it currently suffers from limited applicability due to poor sensitivity, typically in micromolar range. This work presents the design, operation concept, and characterization of a novel microfl uidic device and assay that integrates an oxidized PSi optical biosensor with electrokinetic focusing for a highly sensitive label-free detection of nucleic acids. Under proper oxidation conditions, the delicate nanostructure of PSi can be preserved, while providing suffi cient dielectric insulation for application of high voltages. This enables the use of signal enhancement techniques, which are based on electric fi elds. Here, the DNA target molecules are focused using an electric fi eld within a fi nite and confi ned zone, and this highly concentrated analyte is delivered to an on-chip PSi Fabry-Pérot optical transducer, prefunctionalized with capture probes. Using refl ective interferometric Fourier transform spectroscopy real-time monitoring, a 1000-fold improvement in limit of detection is demonstrated compared to a standard assay, using the same biosensor. Thus, a measured limit of detection of 1 × 10 −9 M is achieved without compromising specifi city. The concepts presented herein can be readily applied to other ionic targets, paving way for the development of other highly sensitive chemical and biochemical assays.

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Heat treatment effect on porous silicon

Cited by 105 publications

References 14 publications

Mechanical Effects of Galvanic Corrosion on Structural Polysilicon

Mechanical Effects of Galvanic Corrosion on Structural Polysilicon

Improved MOCVD growth of GaN on Si‐on‐porous‐silicon substrates

Oxidized Porous Silicon Nanostructures Enabling Electrokinetic Transport for Enhanced DNA Detection

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