Deviatoric Stress Driven Formation of Large Single-Crystal PbS Nanosheet from Nanoparticles and in Situ Monitoring of Oriented Attachment

2011 ◽  
Vol 133 (37) ◽  
pp. 14484-14487 ◽  
Author(s):  
Zhongwu Wang ◽  
Constanze Schliehe ◽  
Tie Wang ◽  
Yasutaka Nagaoka ◽  
Y. Charles Cao ◽  
...  
Keyword(s):  
Single Crystal ◽  
Deviatoric Stress ◽  
In Situ Monitoring ◽  
Oriented Attachment ◽  
Large Single Crystal

scholarly journals Effect of Small Doses of Gamma Radiation on the Optical Properties of Nanostructured Silicon Obtained by Metal-Stimulated Chemical Etching in situ

2020 ◽  
Vol 20 (4) ◽  
pp. 288-298
Author(s):  
Olga Ya. Belobrovaya ◽  
◽  
Victor V. Galushka ◽  
Victoria S. Ismailova ◽  
Valentina P. Polyanskaya ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Porous Silicon ◽  
Radiation Dose ◽  
Single Crystal ◽  
Chemical Etching ◽  
Total Reflection ◽  
In Situ Monitoring ◽  
Main Peak ◽  
Small Doses

Background and Objectives: Porous silicon nanowires (SiNP) obtained by the method of metal stimulated chemical etching (EE method) are of great interest. The physical properties of this material depend significantly on the morphology of the nanostructures and their sizes. Given in the literature data on the effect of small doses of ionizing radiation on metals and alloys and the effect of irradiation on the properties of porous silicon and SiNP, makes sense to modify not only the substrate, but also the SiNP layer during its formation by irradiation. A change in the morphology of the formed layers with increasing in situ irradiation within small doses can affect the properties of SiNP. In the literature known to us, this issue is not considered. This work presents studies of the total reflection, Raman scattering, and photoluminescence of SiNP upon irradiation with γ-rays directly in the production process (in situ). Materials and Methods: The formation of nanoporous silicon structures was performed on non-irradiated and irradiated with small doses of gamma-quanta substrates. The substrates were processed by the Saratov State University’s betatron electron brake accelerator at a maximum energy of Eymax ~ 25 MeV. The radiation dose was 30 and 40 kR. A layer of porous SiNP nanosilicon was formed on irradiated and non-irradiated substrates. Samples were obtained by water-based non-electric etching or metal-stimulated chemical etching. The method of chemical etching EE is based on the replacement of silicon when reducing Ag+ → Agо on the surface of the silicon substrate using Ag in an aqueous solution of AgNO3. Porous silicon structures were formed by a two-stage method on irradiated gamma-quanta and non-irradiated p-type silicon substrates with a resistivity of 4.5 Ω cm, oriented in the plane <111>. The substrate was lowered into an aqueous solution of 0.01 M AgNO3 and 5M HF for 60 s., then was etched in an aqueous solution of 5M HF, 0.5 M H2O2 for 20, 40 and 60 minutes, respectively. The studied nanoporous structures were obtained on irradiated and non-irradiated substrates without irradiation and when irradiated in situ with inhibitory gamma radiation of the medical linear electron accelerator Varian Unique of State Health Institution “Regional Clinical Oncology Dispensary” at an electron energy of 6 MeV. After receiving the samples, they were purified in concentrated nitric acid for an hour. The structural properties of SiNP were studied using measurements on an analytical complex based on the Mira 2 LMU scanning electron microscope, as well as the DRON-4 diffractometer using an x-ray tube with a copper anode (Cu-Ka). Full reflection spectra in the range of 500–1100 nm were obtained using a LOMO SF-56 spectrophotometer equipped with a special integrating set-top box. Raman spectra were recorded using a Renishaw inVia spectrometer. Results: The samples under study are quasiordered ensembles of silicon nanowires oriented almost normal to the substrate. The thickness of the SiNP layer is of the order of 1–8 μm, depending on the preparation conditions, and the diameter of the nanowires was 30–400 nm. In all SiNP samples, a decrease in total reflection was observed in the wavelength range of 400–1000 nm as compared to a single-crystal substrate, which is associated with light scattering on an inhomogeneous structural surface. At the initial stage of the process, the defective state of the substrate was decisive; microstresses on the substrate disappear when it is irradiated. For SiNP samples, total reflection increased with increasing radiation dose over time (from 0 to 24 kR) due to improved surface quality, reduced scattering, and a change in layer thickness. In addition, in situ monitoring of SiNP samples indicates the influence of not only the radiation dose of the formed layer on the reflection value, but also the dose of preliminary irradiation of the substrate. Raman spectra were studied to determine the effect of gamma-irradiation on the properties of porous silicon – SiNP in situ. The intensity of the main peak of Raman scattering of SiNP samples obtained on non-irradiated and irradiated substrates is significantly higher compared to the intensity of the main peak characteristic of single-crystal silicon. Against the background of the high Raman signal, light scattering from particles with broken bonds does not appear and basically gives a maximum – a peak P1 of the order of 519.5 cm-1, slightly shifted to the low-frequency region relative to the maximum of peak P1 of a single-crystal silicon substrate 520 cm-1. An increase in the irradiation dose of the substrate leads to an increase in the intensity of the main Raman peak. Studies of Raman spectroscopy of nanostructured porous silicon-silver layers have revealed the effect of surface giant signal amplification (SERS). The maximum silver content is below the surface of the samples. The depth of the silver-enriched layer is about 250– 400 nm. The photoluminescence peak of SiNP samples formed on irradiated and non- irradiated substrates shifts to the shortwavelength region as the radiation dose increases. The shift is much more dependent on the dose of the substrate than on the irradiation of the layer. The calculated nanocrystallite size by λmax was about 2 nm. Conclusion: The results of an experimental study of the optical properties of porous Si structures obtained by metal-stimulated chemical etching when irradiated with small doses of gamma-quanta directly during in situ formation are presented. In situ monitoring of samples indicates the influence not only of the radiation dose of the resulting layer on the value of total reflection, but also the dose of pre-irradiation of the substrate. Studies of Raman spectroscopy of nanostructured layers of “porous silicon-silver” revealed the effect of surface giant signal amplification in samples. There is a shift in the wavelength of the maximum photoluminescence from 600 nm to 750 nm when the irradiation of the substrate changes from 0 to 40 kR at the same radiation dose of the layer.

scholarly journals Nucleation dynamics of single crystal WS2 from droplet precursors uncovered by in-situ monitoring

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chao Li ◽  
Tomoya Kameyama ◽  
Tomoyuki Takahashi ◽  
Toshiro Kaneko ◽  
Toshiaki Kato
Keyword(s):  
Single Crystal ◽  
Diffusion Length ◽  
Transition Metal Dichalcogenides ◽  
In Situ Monitoring ◽  
Large Area ◽  
Fundamental Study ◽  
Tungsten Disulphide ◽  
Production Stage ◽  
Metal Dichalcogenides

Abstract Transition metal dichalcogenides (TMDs) attract intence attention due to its unique optoelectrical features. Recent progress in production stage of TMD enables us to synthesis uniform and large area TMD with mono layer thickness. Elucidation of growth mechanism is a challenge to improve the crystallinity of TMD, which is regargeded as a next crutial subject in the production stage. Here we report novel diffusion and nucleation dynamics during tungsten disulphide (WS2) growth. The diffusion length (Ld) of the precursors have been measured with unique nucleation control methods. It was revealed that the Ld reaches up to ~750 μm. This ultra-long diffusion can be attributed to precursor droplets observed during in-situ monitoring of WS2 growth. The integrated synthesis of >35,000 single crystals and monolayer WS2 was achieved at the wafer scale based on this model. Our findings are highly significant for both the fundamental study of droplet-mediated crystal growth and the industrial application of integrated single-crystal TMDs.

In Situ Monitoring of the Growth, Intermediate Phase Transformations and Templating of Single Crystal VO2 Nanowires and Nanoplatelets

ACS Nano ◽  
2011 ◽  
Vol 5 (4) ◽  
pp. 3373-3384 ◽  
Author(s):  
Evgheni Strelcov ◽  
Albert V. Davydov ◽  
Uday Lanke ◽  
Clay Watts ◽  
Andrei Kolmakov
Keyword(s):  
Single Crystal ◽  
Phase Transformations ◽  
Intermediate Phase ◽  
In Situ Monitoring

In Situ Monitoring of Electrooxidation Processes at Gold Single Crystal Surfaces Using Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy

2015 ◽  
Vol 137 (24) ◽  
pp. 7648-7651 ◽  
Author(s):  
Chao-Yu Li ◽  
Jin-Chao Dong ◽  
Xi Jin ◽  
Shu Chen ◽  
Rajapandiyan Panneerselvam ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Single Crystal ◽  
In Situ Monitoring ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces

scholarly journals Author Correction: Nucleation dynamics of single crystal WS2 from droplet precursors uncovered by in-situ monitoring

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chao Li ◽  
Tomoya Kameyama ◽  
Tomoyuki Takahashi ◽  
Toshiro Kaneko ◽  
Toshiaki Kato
Keyword(s):  
Single Crystal ◽  
In Situ Monitoring

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

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