scholarly journals Enhanced Microsphere-Assisted Picosecond Laser Processing for Nanohole Fabrication on Silicon via Thin Gold Coating

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 611
Author(s):  
Qiuling Wen ◽  
Xinyu Wei ◽  
Pengcheng Zhang ◽  
Jing Lu ◽  
Feng Jiang ◽  
...  
Keyword(s):  
Silicon Substrate ◽  
Laser Processing ◽  
Picosecond Laser ◽  
Ablation Rate ◽  
Gold Coating ◽  
Cross Sectional ◽  
Simple Method ◽  
Ordered Arrays ◽  
Laser Fluences ◽  
Nanohole Arrays

The nanohole arrays on the silicon substrate can effectively enhance the light absorption in thin film silicon solar cells. In order to optimize the solar energy absorption, polystyrene microspheres with diameters of 1 μm are used to assist picosecond laser with a wavelength of 1064 nm to fabricate nanohole arrays on silicon substrate. The experimental results show that the morphology and size of the silicon nanoholes strongly depend on the laser fluence. At 1.19–1.59 J/cm2 laser fluences, well-ordered arrays of nanoholes were fabricated on silicon substrate, with diameters domain from 250 to 549 nm and depths ranging from 60 to 99 nm. However, large amounts of sputtered nanoparticles appeared around the silicon nanoholes. To improve the surface morphology of silicon nanoholes, a nanolayered gold coating is applied on silicon surface to assist laser processing. The results show that, for gold-coated silicon substrate, sputtered nanoparticles around the nanoholes are almost invisible and the cross-sectional profiles of the nanoholes are smoother. Moreover, the ablation rate of the nanoholes on the gold-coated silicon substrate have increased compared to that of the nanoholes on the uncoated one. This simple method allows fast fabrication of well-ordered nanoholes on silicon substrate without sputtered nanoparticles and with smooth inner surface.

scholarly journals Analytical Study on Pulsed-Laser Processing for Acrylonitrile Butadiene Styrene/ PolyVinyl Chloride

2019 ◽  
Vol 26 (1) ◽  
pp. 77-82 ◽  
Author(s):  
Chang-Wei XIONG ◽  
Si-Li FAN ◽  
Ching-Yen HO
Keyword(s):  
Polyvinyl Chloride ◽  
Laser Processing ◽  
Pulsed Laser ◽  
Acrylonitrile Butadiene Styrene ◽  
Ablation Rate ◽  
Processing Parameters ◽  
Absorption Length ◽  
Laser Fluences ◽  
Short Period ◽  
Butadiene Styrene

This study developed a model involving the energy balance and decomposition at the ablated interface due to the heat transport, optical decomposition and activation energy in Acrylonitrile Butadiene Styrene/PolyVinyl Chloride (ABS/PVC). The prediction for ablation depth obtained from this study is compared with the available experimental data. The predicted results agree with the measured data. The effects of laser processing parameters, optical and thermal properties of ABS/PVC on the variation of the laser-ablated depth with the laser fluences are also discussed. The results validate that the pulsed-laser ablation rate at the initial short period is dominated by optical penetration absorption for laser and is linearly proportional to the logarithm of the laser fluence by a ratio factor “optical absorption length” (i.e., the ablation rate follows Beer’s law at the initial short period).

scholarly journals Thermal stability and diffusion characteristics of ultrathin amorphous carbon films grown on crystalline and nitrogenated silicon substrates by filtered cathodic vacuum arc deposition

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shengxi Wang ◽  
Anurag Roy ◽  
Kyriakos Komvopoulos
Keyword(s):  
Thermal Stability ◽  
Amorphous Carbon ◽  
Silicon Substrate ◽  
Elevated Temperatures ◽  
Carbon Films ◽  
Vacuum Arc ◽  
Cross Sectional ◽  
Prolonged Heating ◽  
Filtered Cathodic Vacuum Arc ◽  
Thermal Stability Of

AbstractAmorphous carbon (a-C) films are widely used as protective overcoats in many technology sectors, principally due to their excellent thermophysical properties and chemical inertness. The growth and thermal stability of sub-5-nm-thick a-C films synthesized by filtered cathodic vacuum arc on pure (crystalline) and nitrogenated (amorphous) silicon substrate surfaces were investigated in this study. Samples of a-C/Si and a-C/SiNx/Si stacks were thermally annealed for various durations and subsequently characterized by high-resolution transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). The TEM images confirmed the continuity and uniformity of the a-C films and the 5-nm-thick SiNx underlayer formed by silicon nitrogenation using radio-frequency sputtering. The EELS analysis of cross-sectional samples revealed the thermal stability of the a-C films and the efficacy of the SiNx underlayer to prevent carbon migration into the silicon substrate, even after prolonged heating. The obtained results provide insight into the important attributes of an underlayer in heated multilayered media for preventing elemental intermixing with the substrate, while preserving the structural stability of the a-C film at the stack surface. An important contribution of this investigation is the establishment of an experimental framework for accurately assessing the thermal stability and elemental diffusion in layered microstructures exposed to elevated temperatures.

Chiral Molecular Cavities of Calix[4]Crown on Au(111)

2008 ◽  
Vol 8 (11) ◽  
pp. 5702-5707 ◽  
Author(s):  
Ge-Bo Pan ◽  
Jun Luo ◽  
Qi-Yu Zheng ◽  
Li-Jun Wan
Keyword(s):  
Self Assembly ◽  
Chiral Recognition ◽  
Scanning Tunneling ◽  
Racemic Mixture ◽  
Tunneling Microscopy ◽  
Geometrical Structures ◽  
Simple Method ◽  
Ordered Structures ◽  
Ordered Arrays ◽  
Stm Images

Well-ordered arrays of chiral molecular cavities have been constructed by self-assembly of inherently chiral calix[4]crown on Au(111) in 0.1 M HClO4 solution and investigated by scanning tunneling microscopy (STM). The chiral features are clearly observed in high resolution STM images. It is found that the adsorption of the two enantiomers results in the same ordered structures with upright orientation on Au(111). Moreover, only phase separation has been observed for the racemic mixture of the two enantiomers in the experiment. This is mainly due to the weak molecule-substrate interaction as well as asymmetric geometrical structures of the two enantiomers. The present study provides a simple method for construction of ordered arrays of chiral molecular cavities, which are of potential in chemical sensors, chiral recognition, and nonlinear optics.

scholarly journals Comparing Patient and Endoscopist Perceptions of the Colonoscopy Indication

2010 ◽  
Vol 24 (11) ◽  
pp. 656-660 ◽  
Author(s):  
Maida J Sewitch ◽  
Dara Stein ◽  
Lawrence Joseph ◽  
Alain Bitton ◽  
Robert J Hilsden ◽  
...  
Keyword(s):  
Kappa Statistic ◽  
Cross Sectional Study ◽  
Routine Screening ◽  
Self Report ◽  
Administrative Databases ◽  
Screening Colonoscopy ◽  
Cross Sectional ◽  
Simple Method ◽  
Patient Questionnaires

BACKGROUND: Determining whether a colonoscopy is performed for screening or nonscreening purposes can facilitate clinical practice and research. However, there is no simple method to determine the colonoscopy indication using patient medical files or health administrative databases.OBJECTIVE: To determine patient-endoscopist agreement on the colonoscopy indication.METHODS: A cross-sectional study was conducted among staff endoscopists and their patients at seven university-affiliated hospitals in Montreal, Quebec. The study participants were 50 to 75 years of age, they were able to understand English or French, and were about to undergo colonoscopy. Self- (endoscopist) and interviewer-administered (patient) questionnaires ascertained information that permitted classification of the colonoscopy indication. Patient colonoscopy indication was defined as the following: perceived screening (routine screening, family history, age); perceived nonscreening (follow-up); medical history that implied nonscreening; and a combination of the three preceding indications. Agreement between patient and endoscopist indications was measured using concordance and Kappa statistic.RESULTS: In total, 702 patients and 38 endoscopists participated. The three most common reasons for undergoing colonoscopy were routine screening/regular check-up (33.8%), follow-up to a previous problem (30.2%) and other problem (24.6%). Concordance (range 0.79 to 0.85) and Kappa (range 0.58 to 0.70) were highest for perceived nonscreening colonoscopy. Recent large bowel symptoms accounted for 120 occurrences of disagreement in which the patient perceived a nonscreening colonoscopy while the endoscopist perceived a screening colonoscopy.CONCLUSIONS: Patient self-report may be an acceptable means for rapidly assessing whether a colonoscopy is performed for screening or nonscreening purposes. Delivery of patient-centred care may help patients and endoscopists reach a shared understanding of the reason for colonoscopy.

Effect of Laser Processing Parameters on Microhole Quality of Aluminium Nitride Ceramics

2021 ◽  
Vol 871 ◽  
pp. 277-283
Author(s):  
Chun Yan Yang ◽  
Yun Hao ◽  
Bozhe Wang ◽  
Hai Yuan ◽  
Liu Hui Li
Keyword(s):  
Laser Processing ◽  
Laser Power ◽  
Picosecond Laser ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Recast Layer ◽  
Aluminium Nitride ◽  
Obvious Effect ◽  
Nitride Ceramics

A picosecond laser in spin-cutting mode was used to drill 500μm diameter microholes on 150μm thick aluminium nitride ceramic. The effects of laser processing parameters such as the laser power, scanning speed, and defocus amount on the microhole quality were studied. The results show that as the laser power increases, the inlet and outlet diameters of the holes increase, the taper decreases slightly, and the thickness of the recast layer decreases evidently. The scanning speed has no obvious effect on the diameter and taper of the hole; however, the hole can not be drilled through when the speed is too large. Positive defocus can effectively reduce the taper of the hole. Under 28.5W laser power, 400Hz frequency, 200mm/s scanning speed, and zero defocus amount conditions, high-quality microholes with a taper of 0.85° were obtained.

Research and Application of Massive Micropores Water-Assisted Picosecond Laser Processing Technology

2020 ◽  
Vol 47 (3) ◽  
pp. 0302002
Author(s):  
朱帅杰 Zhu Shuaijie ◽  
张朝阳 Zhang Zhaoyang ◽  
储松林 Chu Songlin ◽  
杨志逸 Yang Zhiyi ◽  
张先烁 Zhang Xianshuo ◽  
...  
Keyword(s):  
Laser Processing ◽  
Picosecond Laser ◽  
Processing Technology

scholarly journals The Hayman Technique: A Simple Method to Treat Postpartum Hemorrhage due to Placenta Praevia

2018 ◽  
Vol 30 (1) ◽  
pp. 66-69
Author(s):  
Shahela Jesmin ◽  
Nishat Anam Borna ◽  
Mosammat Nargis Shamima ◽  
Iftekhar Md Kudrate E Khuda ◽  
Shahin Mahmuda
Keyword(s):  
Postpartum Haemorrhage ◽  
Uterine Cavity ◽  
Placenta Praevia ◽  
Artery Ligation ◽  
College Hospital ◽  
Cross Sectional ◽  
Simple Method ◽  
Medical College ◽  
Compression Suture ◽  
Level Hospital

Aim: To assess effectiveness of Hayman suture to control postpartum haemorrhage due to placenta praevia during caesarean sectionMethods: It is a cross sectional observational study performed in Rajshahi Medical College Hospital, tertiary level hospital, from January 2016 to December 2016. It included 32 patients with PPH following placenta praevia during elective& emergency caesarean section (C/S). All 32 patients underwent horizontal compression suture (bilateral anteroposterior compression) of lower uterine segment. Vicryl 0 tapercut needle was used. All patients were followed postpartum for evaluation of uterine cavity and menstrual cycles.Results Hayman suture was applied in 32 cases. In 27 cases Hayman suture was the only intervention. Hayman with uterine artery ligation required in 2 cases. In 1 patient along with Hayman B-lynch compression suture was given and 2 patients required total hysterectomy.Conclusion: The quick and simple Hayman technique seems to be effective, safe, lifesaving method in stopping hemorrhage due to placenta praevia.TAJ 2017; 30(1): 66-69

scholarly journals Fabrication and Characterization of Biplasmonic Substrates Obtained by Picosecond Laser Pulses

2020 ◽  
Vol 10 (17) ◽  
pp. 5938
Author(s):  
Andrei Stochioiu ◽  
Catalin Luculescu ◽  
Irina Alexandra Paun ◽  
Luiza-Izabela Jinga ◽  
Constantin Stochioiu
Keyword(s):  
Picosecond Laser ◽  
Laser Pulses ◽  
Surface Enhanced Raman Spectroscopy ◽  
Electromagnetic Properties ◽  
Large Area ◽  
Laser Fluences ◽  
Picosecond Laser Pulses ◽  
Bimetallic Nanocrystals ◽  
Surface Enhanced Raman ◽  
Bimetallic Nanostructures

Bimetallic nanostructures have the potential to become the new generation candidates for applications in catalysis, electronics, optoelectronics, biosensors and also for surface-enhanced Raman Spectroscopy (SERS). The bimetallic nanocrystals offer additional properties over the single metal components such as improved electromagnetic properties and corrosion protection. This work presents a simple and inexpensive method to fabricate large area biplasmonic (bimetallic) substrates, employing DC magnetron sputtering, picosecond laser pulses and a digital galvanometric scanner. The aim of this study was to achieve large area homogeneous substrates while having a good and predictable signal amplification by SERS effect. Gold thin films with 200 nm thickness were deposited on optical polished substrates and then irradiated in atmospheric air with λ = 1064 nm wavelength laser pulses with 8 ps pulse duration and 500 kHz fixed repetition rate. Various laser fluences and laser irradiation speeds were employed in order to optimize the Laser-Induced Periodic Surface Structures (LIPSS) formed on the substrate. The results are presented comparatively for the standalone Cu substrates and for the Cu-Au substrates using Raman spectral analysis on a single signal peak of a Rhodamine 6G solution.

Sign in / Sign up

Export Citation Format

Share Document