Microcavities in Semiconductor Materials

Veen, A. van; Hakvoort, Rudi A.; Schüt, H.; Mijnarends, P.E.

doi:10.1051/jp4:1995104

Cited by 8 publications

(11 citation statements)

References 8 publications

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“…The nanostructure parameter K, which can be deduced from FTIR analysis, is defined as the number of hydrogen atoms in the volume of a missing Si atom and indicates the dominant type of hydrogenated vacancy [7,9]. In this work it is shown that the S parameter correlates strongly with the found nanostructure parameter K. The dominant type of open volume deficiency in device grade a-Si:H seems to be the divacancy, which is in line with earlier observations from positron annihilation lifetime spectroscopy (PALS) [4], DB-PAS [3,5] and FTIR [9] studies. This result further underlines the important role of hydrogenated divacancies in a-Si:H, which has recently been illustrated in detail [9].…”

Section: Introductionsupporting

confidence: 82%

“…open volume deficiencies. The following S/S c-Si values have been reported [3][4][5]: monovacancies 1.030, divacancies 1.034-1.038, vacancy clusters 1.047-1.061, and microvoids 1.10-1.14.…”

Section: Resultsmentioning

confidence: 93%

“…Therefore, in this contribution we present a detailed study on a set of Si:H samples with a wide variety of nanostructural properties including dense up to porous films and amorphous up to highly crystalline films. To gain more insight into the Si:H nanostructure we use a combination of positron annihilation spectroscopy (PAS) [2][3][4][5][6] and Fourier Transform infrared (FTIR) spectroscopy [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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The nanostructural analysis of hydrogenated silicon films based on positron annihilation studies

Melskens

Smets

Eijt³

et al. 2012

Journal of Non-Crystalline Solids

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Section: Introductionsupporting

confidence: 82%

“…open volume deficiencies. The following S/S c-Si values have been reported [3][4][5]: monovacancies 1.030, divacancies 1.034-1.038, vacancy clusters 1.047-1.061, and microvoids 1.10-1.14.…”

Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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The nanostructural analysis of hydrogenated silicon films based on positron annihilation studies

Melskens

Smets

Eijt³

et al. 2012

Journal of Non-Crystalline Solids

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“…This can be explained only by contribution of Ps formed on inner surfaces of micro-cavities in the sub-surface region of the black Au film. Narrow momentum distribution of para-positronium (p-Ps) contribution [16] enhances the S parameter while Ps diffusion in cavities interconnected with surface leads to a longer diffusion length determined by VEPFIT. This picture was verified by measurement of the contribution of 3 − γ annihilations to energy spectra of annihilation radiation.…”

Section: Resultsmentioning

confidence: 99%

Positronium Formation in Nanostructured Metals

et al. 2017

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Positronium formation in Au films was studied using a magnetically guided continuous slow positron beam with variable energy. Black Au film with porous morphology was compared with conventional smooth Au film. In the smooth Au film positronium is formed on the film surface only. The black Au film exhibits porous sub-surface region containing micro-cavities interconnected with surface. Positronium is formed on inner surfaces of microcavities in the sub-surface region and travels through interconnected cavities towards the surface. 3−γ annihilation of ortho-positronium leaves a clear signature in two-dimensional coincidence Doppler broadening spectra. Measures of 3 − γ annihilation contribution calculated from single γ-ray and coincidence Doppler broadening spectra were calculated and compared.

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“…However, a thermalized positron escaping from Au through inner surface into a cavity may form Ps by picking an electron on the surface. Narrow para-Ps contribution to the annihilation photopeak [10] likely caused the observed enhancement of S in the sub-surface region. Enhanced L + can be explained by Ps diffusion through percolated network of cavities in the sub-surface region.…”

Section: Bulk Au Samplesmentioning

confidence: 99%

Positron annihilation study of cavities in black Au films

Melikhova

Čı́žek

Hruška

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. Defects in a black Au film were studied using variable energy positron annihilation spectroscopy. Black Au films exhibit porous morphology similar to cauliflower. This type of structure enhances the optical absorption due to a multiple reflections in the micro-cavities. A nanostructured black Au film was compared with conventional smooth Au films with high reflectivity. The black Au film exhibited a remarkably enhanced S-parameter in sub-surface region. This is caused by a narrow para-Positronium contribution to the annihilation peak. IntroductionLight absorbers are needed in optical applications for preventing crosstalk between optical connections and for thermal light-emitting sources. A complete absorption of light from the visible into the infrared spectral region over the whole range of incident angles remains still a challenge [1]. This goal could be achieved in nanostructured metal surfaces containing a broad size distribution of cavities that sustain localized optical excitations [2]. Metals evaporated in the presence of a gas with pressure of about 100 Pa deposit as porous layers called black metals [3]. Their porous structure with percolated microcavities leads to high absorbance in the visible to infrared spectral region. Black metals, in particular black Au, are therefore highly suitable as absorbers [4]. The surface morphology and the structure of cavities in sub-surface region are crucial for performance of black metals absorbers. In the present work variable energy positron annihilation spectroscopy (VEPAS) was employed for characterization of cavities in black Au film. Microstructures of black Au and a conventional smooth Au film were compared. Note that a conventional smooth Au films have been already studied by VEPAS in Ref. [5].

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Microcavities in Semiconductor Materials

Cited by 8 publications

References 8 publications

The nanostructural analysis of hydrogenated silicon films based on positron annihilation studies

The nanostructural analysis of hydrogenated silicon films based on positron annihilation studies

Positronium Formation in Nanostructured Metals

Positron annihilation study of cavities in black Au films

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