Nanoparticle formation in low-pressure silane plasmas: bridging the gap between a-Si:H and μc-Si films

Cabarrocas, Pere Roca i; Hamma, S.; Sharma, S.N.; Viera, G.; Bertrán, E.; Costa, J.

doi:10.1016/s0022-3093(98)00200-2

Cited by 96 publications

(46 citation statements)

References 15 publications

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“…This process is detected as a higher temperature shoulder in Si nanoparticles and is almost undetectable in a-Si:H. Independent studies 8,19 19,20 has led us propose that it corresponds to hydrogen bonded on the surfaces of nanoparticles or silicon clusters. In fact, the plasma conditions of pm-Si:H are such that, in addition to SiH x radicals, clusters do contribute to the film growth.…”

Section: A Hydrogen Statesmentioning

confidence: 95%

Thermally Induced Structural Transformations on Polymorphous Silicon

et al. 2005

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Polymorphous Si is a nanostructured form of hydrogenated amorphous Si that contains a small fraction of Si nanocrystals or clusters. Its thermally induced transformations such as relaxation, dehydrogenation, and crystallization have been studied by calorimetry and evolved gas analysis as a complementary technique. The observed behavior has been compared to that of conventional hydrogenated amorphous Si and amorphous Si nanoparticles. In the temperature range of our experiments (650-700°C), crystallization takes place at almost the same temperature in polymorphous and in amorphous Si. In contrast, dehydrogenation processes reflect the presence of different hydrogen states. The calorimetry and evolved gas analysis thermograms clearly show that polymorphous Si shares hydrogen states of both amorphous Si and Si nanoparticles. Finally, the total energy of the main Si-H group present in polymorphous Si has been quantified.

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Section: A Hydrogen Statesmentioning

confidence: 95%

Thermally Induced Structural Transformations on Polymorphous Silicon

et al. 2005

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“…8,9 von Keudell and Abelson also studied the thermal annealing behavior of the platelet-like defects in a-Si: H films and found that H atoms in this configuration are released from the film at temperatures greater than 300°C. 29 In recent IR studies of a-Si: H exposure to H, this absorption mode centered at ϳ2033 cm −1 has also been reported by Roca i Cabarrocas and co-workers 30 and by Fujiwara and co-workers. 22 In this work we have performed isotope exchange and short-and long-term annealing experiments to confirm if the vibrational bands at ϳ1945 and ϳ2033 cm −1 in a-Si: H could be due to the stretching modes of Si-H bonds in BCH and platelet-like configurations.…”

Section: B Platelet-like H In Simentioning

confidence: 53%

Hydrogen in Si–Si bond center and platelet-like defect configurations in amorphous hydrogenated silicon

Agarwal¹,

Hoex²,

Sanden³

et al. 2004

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Hydrogen and deuterium in bond-centered (BC) and platelet-like configurations were detected in hydrogenated (and deuterated) amorphous silicon thin films deposited from SiH4 and SiD4 plasmas. Infrared absorptions due to these configurations were measured using in situ multiple total internal reflection Fourier transform infrared spectroscopy in a differential mode, where changes in the as-deposited a-Si:H(D) films were observed during D2(H2) plasma exposure. This method coupled with preferential replacement of H(D) by D(H) in BC and platelet-like configurations over the isolated bulk SiH(SiD) configurations enabled detection of these modes without interference from the strong SiH(SiD) absorptions. The Si–H(D) stretching modes for BC hydrogen and BC deuterium were observed at ∼1950 and ∼1420cm−1, respectively, while those for platelet-like hydrogen and deuterium were detected at ∼2033 and ∼1480cm−1, respectively.

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“…IR (hydrogen bonding configurations), spectroscopic ellipsometry (film nucleation, growth, and microcrystallinity), AFM (surface topography), internal friction, Urbach energy, hydrogen evolution, residual stress, and mass density. Several of the studies have used the more direct structural methods of transmission electron microscopy (TEM) [4,5,10,11,21] and x-ray diffraction (XRD) [7,10,12,18]. High-resolution TEM has provided direct evidence of ordered regions on the nanometer scale within the amorphous matrix of the high-hydrogen-diluted PECVD material [4,5,10] and cross-sectional TEM of HWCVD material shows the onset of crystallinity near the substrate with increasing film thickness [21].…”

Section: List Of Tablesmentioning

confidence: 99%

“…Several of the studies have used the more direct structural methods of transmission electron microscopy (TEM) [4,5,10,11,21] and x-ray diffraction (XRD) [7,10,12,18]. High-resolution TEM has provided direct evidence of ordered regions on the nanometer scale within the amorphous matrix of the high-hydrogen-diluted PECVD material [4,5,10] and cross-sectional TEM of HWCVD material shows the onset of crystallinity near the substrate with increasing film thickness [21]. In addition to providing direct information on the degree of microcrystallinity [7,10,12] and its sensitivity to the nature of the substrate [12], XRD has recently been used to show direct evidence of improved medium-range order in both the elevatedsubstrate-temperature HWCVD material [18] and in the high-hydrogen-dilution PECVD films [12].…”

Section: List Of Tablesmentioning

confidence: 99%

Nanostructure of a-Si:H and related alloys by small-angle scattering of neutrons and X-rays: Annual technical progress report: May 22, 1998 -- May 21, 1999

Williamson¹

1999

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The materials for analyses were supplied by NREL-supported device-making groups as well as by other groups with relevant expertise. Electron microprobe analyses of film compositions were carried out by Alice Mason of NREL. The co-P.I., David Marr, of the Chemical Engineering Department of the Colorado School of Mines, contributed to the research project via assistance in the preparation of the proposal to NIST for the small-angle neutron scattering experiments and via assistance in the design of the samples for these experiments. OBJECTIVES/APPROACHThe general objective of this research is to provide detailed microstructural information on the amorphous-silicon-based, thin-film materials under development for improved multijunction solar cells. Correlation of this microstructure with opto-electronic properties and device performance is an integral part of the research. The principal experimental techniques used are small-angle x-ray scattering (SAXS), small-angle neutron scattering (SANS), and conventional xray diffraction (XRD). These provide quantitative microstructural data on microvoid fractions, sizes, shapes, preferred orientations, hydrogen clustering, microcrystallinity, and medium-range order. An important task is to establish whether SANS can be used to determine the hydrogen nanostructure and any changes that might occur due to light soaking. Some experiments are conducted using anomalous SAXS (ASAXS) via special facilities in Germany. This method provides information on the Ge uniformity and nanostructure in a-SiGe:H alloys. Two types of material have been investigated during this first phase of the research in collaboration with the NREL Low-gap and Mid-gap/Metastability National Teams. Some of the films will be put in the light-soaked state prior to the SANS experiments so that SANS measurements followed by in-situ annealing and further SANS can be performed to look for any light-induced structural change.iv List of Tables INTRODUCTIONSeveral experiments have been completed during Phase I of this research project in collaboration with NREL and NREL-supported groups. The planned SANS studies have been delayed due to an unexpected shut-down of the research nuclear reactor at the NIST Center for Neutron Research in Gaithersburg, Maryland. However, the facility is again operational and SANS beam time has been awarded to us for three days beginning on August 9, 1999. A summary of the samples being prepared for this experiment will be presented below. The results and discussion of the in-house SAXS and XRD experiments will be broken into sections according to whether the materials are low-gap, mid-gap, and high-gap, consistent with the NREL team structure. We have not received any high-gap materials for study during Phase I.Several experiments were done with mid-gap materials. A systematic study of the mediumrange order (MRO) of PECVD and HWCVD a-Si:H films was done in collaboration with USSC, University of Oregon, and NREL. Discoveries were made on microcrystalline (µc)-Si:H formation in highly-hydro...

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Nanoparticle formation in low-pressure silane plasmas: bridging the gap between a-Si:H and μc-Si films

Cited by 96 publications

References 15 publications

Thermally Induced Structural Transformations on Polymorphous Silicon

Thermally Induced Structural Transformations on Polymorphous Silicon

Hydrogen in Si–Si bond center and platelet-like defect configurations in amorphous hydrogenated silicon

Nanostructure of a-Si:H and related alloys by small-angle scattering of neutrons and X-rays: Annual technical progress report: May 22, 1998 -- May 21, 1999

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