Structure of Porous Silicon Layer and Heat‐Treatment Effect

Unagami, Takashi; Seki, Masanori

doi:10.1149/1.2131674

Cited by 118 publications

(31 citation statements)

References 6 publications

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“…In the cross-sectional view (Fig. 6e) the socalled tree-like structures corresponding to the porous structures, 20,21 which are perpendicular to the silicon substrate, can be observed. After NaOH treatment for 10 s ( Fig.…”

Section: Photoluminescence Change Of As-prepared and Aged Porous Silimentioning

confidence: 99%

Photoluminescence Change of As‐Prepared and Aged Porous Silicon with NaOH Treatment

Fukuda

Zhou

Furuya

et al. 1999

J. Electrochem. Soc.

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Porous silicon (PS) formed electrochemically on crystalline silicon shows visible photoluminescence (PL) at room temperature. 1 It is widely acknowledged that the visible PL can be explained basically in terms of the quantum confinement model. 1,2 However, a number of experimental data inconsistent with this model have also been observed and alternative explanations proposed. Koch et al. 3 proposed the radiation recombination model involving surface-confined states on the nanocrystals. In addition, siloxene derivatives, 4 SiH 2 , 5 or oxide defects 6 on the surface of Si particles are suggested to be the origin of the PL. Many researchers 7-11 demonstrated PL quenching by a variety of chemical modification of the internal surface of PS. Recently, Gole et al. 12 have proposed surface-bounded Si oxyhydride moieties as the source of the PL. The authors 13 reported that the Si-O bond content in PS increases with aging time and correlates to the PL intensity. It is therefore considered that the visible PL may be ascribed to not only the nanosize effect but also to some surface state. Qin and Jia 14 suggested the quantum confinement/ luminescence center model. However, few studies have been reported on the PL properties related to both the chemical states and structures of PS layer. This paper presents an analysis of as-prepared low resistivity p-type PS and PS aged for 15 months, which are chemically etched with aqueous NaOH. Also the correlations among PL properties, chemical states, and microstructures of the PS layer are investigated to clarify the origin of PL.Experimental PS samples were prepared by anodizing boron-doped p-type Si(100) wafers with resistivity of 0.04-0.06 ⍀ cm and size of 13 ϫ 13 ϫ 0.5 mm. The anodization was carried out in a 50% HF-ethanol (1:1) solution at room temperature (297 K) and at a constant current density of 0.35 A/cm 2 for 10 s. An electrical contact was made to the back of the wafer, and only an area of the front surface of 10 mm in diam was exposed to the anodizing solution using a sample holder made of Teflon. The anodized samples were rinsed with deionized water and ethanol, and dried under air blow (as-prepared PS). The resultant PS layer thickness, observed with a scanning electron microscope, was approximately 2.2 m. In addition, PS samples aged in a desiccator at room temperature for 15 months were used (aged PS). The chemical etching treatment of PS samples was carried out by immersion in 0.05% aqueous NaOH at room temperature for 10 to 450 s. The treated samples were rinsed in deionized water, and dried in air after absorbing water on their surfaces with filter paper. The 1 M (ca. 4%) aqueous NaOH treatment of n-and p-type PS layers was reported to have the effect of dissolving the surface oxide completely. 15 The NaOH solution used in this work was much more dilute than the one above.PL spectroscopy was performed at room temperature by using a photoluminescence-lifetime measurement system with a streak scope (Hamamatsu Photonics, C4780). Excitation source was a nitrogen l...

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Section: Photoluminescence Change Of As-prepared and Aged Porous Silimentioning

confidence: 99%

Photoluminescence Change of As‐Prepared and Aged Porous Silicon with NaOH Treatment

Fukuda

Zhou

Furuya

et al. 1999

J. Electrochem. Soc.

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“…In our previous study, the PSi layer changed into a foamlike structure filled with several 100-nm-scale pores during the initial growth stage of GaN layer after the AlN IL growth [7] as a result of the migration of silicon in PSi [9]. Some of the pores appeared as voids at the interface between the nitride layers and PSi, leading to pits on the GaN surface.…”

Section: Methodsmentioning

confidence: 91%

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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“…The damage and extended defects are annealed out and then can no longer trap the impurities. Polysilicon recrystallizes and results in the reduction of gettering efficiency.1 36 Although the heat treatment effect 137 (pores coarsen at an elevated temperature) can reduce the specific surface area, the microstructure of PS can be stabilized through a low temperature (300°C) dry oxidation process as discussed in Chapter 2. The PS patch performs as a reasonably stable extrinsic gettering center.…”

Section: Resultsmentioning

confidence: 99%

The processing and potential applications of porous silicon

Shieh

1992

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Structure of Porous Silicon Layer and Heat‐Treatment Effect

Cited by 118 publications

References 6 publications

Photoluminescence Change of As‐Prepared and Aged Porous Silicon with NaOH Treatment

Photoluminescence Change of As‐Prepared and Aged Porous Silicon with NaOH Treatment

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

The processing and potential applications of porous silicon

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