Revealing inhomogeneous Si incorporation into GaN at the nanometer scale by electrochemical etching

Nanoscale ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 6137-6143 ◽  
Author(s):  
Marta Sawicka ◽  
Natalia Fiuczek ◽  
Henryk Turski ◽  
Grzegorz Muziol ◽  
Marcin Siekacz ◽  
...  
Keyword(s):  
Electrochemical Etching ◽  
Nanometer Scale ◽  
Step Bunching

Step-bunching during epitaxy induces inhomogeneous incorporation of a Si dopant into GaN at the nanometer scale as revealed by electrochemical etching.

Fabrication of Micro- and Nanoscale SiC Structures Using Selective Deposition Processes

2003 ◽  
Vol 782 ◽  
Author(s):  
L. Chen ◽  
X. A. Fu ◽  
C. A. Zorman ◽  
M. Mehregany
Keyword(s):  
Thin Film ◽  
Growth Process ◽  
Electrochemical Etching ◽  
Nanometer Scale ◽  
Selective Deposition ◽  
Si Substrates ◽  
Deposition Processes ◽  
Sic Films ◽  
Stable Structures

ABSTRACTA method to fabricate nanometer scale SiC beams and nanoporous SiC shells using conventional microlithographic techniques combined with selective APCVD has been developed as an alternative to nanolithographic patterning and electrochemical etching. The process involves the selective deposition of poly-SiC films on patterned SiO2/polysilicon/SiO2 thin film multilayers on (100) Si substrates using a carbonization-based 3C-SiC growth process. This technique capitalizes on significant differences in the nucleation of SiC on SiO2 and polysilicon surfaces in order to form mechanically durable and chemically stable structures.

Focused Ion-Beam Based Nanohole Modeling, Simulation, Fabrication, and Application

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Jack Zhou ◽  
Guoliang Yang
Keyword(s):  
Thin Film ◽  
Focused Ion Beam ◽  
Electrochemical Etching ◽  
Ion Beam ◽  
Machining Process ◽  
Nanometer Scale ◽  
Free Standing ◽  
Single Digit ◽  
Epitaxial Deposition ◽  
And Control

There are three major steps toward the fabrication of a single-digit nanohole: (1) preparing the free-standing thin film by epitaxial deposition and electrochemical etching, (2) making submicron holes (0.2–0.02 μm) by focused ion beam (FIB), and (3) reducing the hole to less than 10 nm by FIB-induced deposition. One specific aim for this paper is to model, simulate, and control the focused ion-beam machining process to fabricate holes that can reach a single-digit nanometer scale on solid-state thin films. Preliminary work has been done on the thin film (30 nm in thickness) preparation, submicron hole fabrication, and ion-beam-induced deposition, and the results are presented.

Cost Effective Fabrication of Wafer Scale Nanoholes for Solar Cells Application

2011 ◽  
Vol 1323 ◽  
Author(s):  
Y Q Zhao ◽  
K K Leung ◽  
C Surya ◽  
C K Feng ◽  
Y F Chen ◽  
...  
Keyword(s):  
Solar Cells ◽  
Silver Film ◽  
Electrochemical Etching ◽  
Cost Effective ◽  
Nanometer Scale ◽  
Cell Efficiency ◽  
Annealing Conditions ◽  
Metal Catalyzed ◽  
Film Annealing ◽  
Si Wafer

ABSTRACTWe report fabrication of random nanometer-scale radial p-n junction solar cells (SCs). Nanoholes were fabricated on the Si wafer by combining silver film annealing and metal catalyzed electrochemical etching (MECC) of the material. The dimension of the holes can be adjusted by varying the annealing conditions and the thickness of the Ag film. Systematic investigations on the effects of the nanohole size and the doping conditions on the cell efficiency were performed.

Fabrication of Superhydrophobic Surfaces on Aluminum Substrates via Electrochemical Etching and Re-Deposition

2012 ◽  
Vol 197 ◽  
pp. 351-355 ◽  
Author(s):  
Jin Long Song ◽  
Xin Liu ◽  
Yao Lu ◽  
Li Bo Wu ◽  
Wen Ji Xu
Keyword(s):  
Electrochemical Etching ◽  
Superhydrophobic Surfaces ◽  
Aluminum Surface ◽  
Nanometer Scale ◽  
Water Contact ◽  
Leaf Surfaces ◽  
Main Components ◽  
Aluminum Substrates ◽  
Micrometer Scale ◽  
Micro Structures

Superhydrophobic surfaces on metal substrates are often prepared via roughing the surfaces and lowering their surface energy. The superhydrophobic aluminum surface with a water contact angle of 162.5° and rolling angle less than 6° was fabricated via electrochemical etching and re-deposition using the alkalic Na3PO4 electrolyte and then fluorination treating. The surface morphology and chemical composition were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results show that the surface consists of the micrometer-scale lumps and protrusions, and many nanometer-scale mastoids are filled in these protrusions. These hierarchical micro/nanometer-scale binary structures, which are similar to the micro-structures of lotus leaf surfaces, play an important role in achieving superhydrophobicity. The main components of the binary geometric structures are Al2O3, AlPO4, and H2O. The effects of the processing time and processing voltage on the macro-morphology were also investigated. The macro-rough structures appeared on the edge of the aluminum surface firstly, and then spread gradually to the entire surface.

Investigation of Electrochemical Nanostructuring with Ultrashort Pulses by Using Nanoscale Electrode

2019 ◽  
Vol 15 (3) ◽  
pp. 279-288 ◽  
Author(s):  
Yong Liu ◽  
Xiujuan Wu ◽  
Huanghai Kong
Keyword(s):  
Power Supply ◽  
Ultrashort Pulse ◽  
Liquid Membrane ◽  
Electrochemical Etching ◽  
Electrochemical Machining ◽  
Ultrashort Pulses ◽  
Pulse Power ◽  
Nanometer Scale ◽  
Machining Parameters ◽  
Pulse Power Supply

Background: Electrochemical machining (ECM) is a non-traditional machining method for the metal material based on the principle of anode electrochemical dissolution which has been used in micro/nano fabrication with advantages as not influenced by materials intensity and hardness, no residual stress and no heat treatment born on the surface of the workpiece. Several researches and applications have shown that the surface quality can be improved effectively during the electrochemical machining by using ultrashort pulse power supply. Method: This paper presents a potential of electrochemical machining at the nanometer scale. First, a transient charging double layer mathematical model is developed to describe electrochemical nanostructuring of metallic materials with ultrashort (nanosecond) voltage pulses. And then, by using finite element method (FEM), the analysis model of electrochemical interface between poles is established to give a more realistic analysis of the comparison of transient currents at different separations between the tool and workpiece. Second, a nanoscale electrode is an essential tool in electrochemical nanostructuring. In this paper, electrodes with diameters of several ten to hundred nanometers are successfully prepared by the liquid membrane electrochemical etching. Finally, by using the nanometer scale electrodes above and the ultrashort pulse power supply, several nanostructures with physical dimension of several hundred nanometers are fabricated on nickelbased superalloys. Results: Using the optimal machining parameters, a tool electrode with 230 nm in diameter is obtained from the initial tungsten rod radius of 100 μm. By using 0.05 M H2SO4 solution, the pulse generator with 1μs in period, 100 ns in pulse on-time and 4 V in voltage, a micro/nano groove with the depth of 150 nm and maximum entrance width of 3 μm is obtained. Conclusion: Nanoscale electrodes with diameters of several ten to hundred nanometers is obtained successfully demonstrating that the liquid membrane electrochemical etching is a very effective method to fabricate nanoscale electrode. Several nanostructures with physical dimension of several hundred nanometers can be fabricated successfully demonstrating that ECM with ultrashort pulses is a highly promising nanostructuring technology.

Fabrication Technology of Low-Adhesive Superhydrophobic and Superamphiphobic Surfaces Based on Electrochemical Machining Method

2013 ◽  
Vol 1 (2) ◽  
Author(s):  
Jinlong Song ◽  
Wenji Xu ◽  
Yao Lu ◽  
Limei Luo ◽  
Xin Liu ◽  
...  
Keyword(s):  
Contact Angle ◽  
Magnesium Alloy ◽  
Electrochemical Etching ◽  
Electrochemical Machining ◽  
Superhydrophobic Surfaces ◽  
Nanometer Scale ◽  
Rolling Angle ◽  
Water Contact ◽  
Micrometer Scale ◽  
Steel Substrates

Low-adhesive superhydrophobic and superamphiphobic (both superhydrophobic and superoleophobic) surfaces with a liquid contact angle larger than 150 deg and rolling angle less than 10 deg have attracted great interest for fundamental research and potential application. However, the existing methods to fabricate the aforementioned surfaces are contaminative, dangerous, expensive, and time-consuming. Low-adhesive superhydrophobic surfaces on aluminum substrates and steel substrates were fabricated via electrochemical etching method and electrochemical deposition method, respectively. Low-adhesive superamphiphobic surfaces on magnesium alloy substrates were fabricated via one-step electrochemical etching method. The sample surfaces were investigated using electron microscopy, energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectrophotometry (FTIR), X-ray diffraction (XRD), optical contact angle measurements, and digital roughness and microhardness measurements. The SEM results show that the hierarchical rough structures composed of micrometer-scale pits, protrusions, rectangular-shaped plateaus, and smaller step-like structures and particles are present on the aluminum surfaces after electrochemical etching; meanwhile, the hierarchical micro/nanometer-scale rough structures composed of micrometer-scale globular structures and nanometer-scale SiO2 particles are present on the steel surfaces. After being modified with a low surface energy material, superhydrophobic surfaces on aluminum substrates with 167.0 deg water contact angle and 2 deg rolling angle and superhydrophobic surfaces on steel substrates with 172.9 deg water contact angle and 1 deg rolling angle are obtained. For magnesium alloy, the hierarchical micro/nanometer-scale rough structures composed of micrometer-scale, grain-like structures, protrusions, pits, globular structures, lump-like structures, and nanometer-scale sheets and needles are present on the magnesium alloy surfaces. After obtaining the hierarchical micro/nanometer-scale rough structures, the magnesium alloy surfaces directly show a superamphiphobicity without any chemical modification. The hierarchical rough structures are essential to fabricate superhydrophobic surfaces. In addition, the re-entrant structures are important to fabricate superamphiphobic surfaces. Furthermore, the proposed electrochemical machining method is simple, economic, and highly effective.

DETERMINATION OF NANOMETER-SCALE SIZES IN n+-TYPE POROUS SILICON BY THE USE OF X-RAY AND RAMAN SPECTROSCOPIES

2002 ◽  
Vol 09 (05n06) ◽  
pp. 1769-1772
Author(s):  
A. RAMÍREZ-PORRAS
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Uv Light ◽  
Electrochemical Etching ◽  
Nanometer Scale ◽  
X Ray ◽  
Recombination Processes ◽  
Phosphorus Doped ◽  
Confinement Model

Porous silicon layers were obtained by electrochemical etching on (111) plane surfaces of crystalline phosphorus-doped silicon in the presence of hydrofluoric acid. The photoluminescence of this kind of layers when illuminated with UV light is possibly explained by the quantum confinement model (QCM), which states the presence of nanometer-scale crystallites that enlarge the semiconductor band gap up to optical photon energies when the band-to-band recombination processes take place. In this study, the size determination of those proposed structures was performed by X-ray diffractiometry and by Raman spectroscopy. The obtained results suggest a consistency between the experimental work and the QCM.

Analyzing reactions of single mechanoenzyme molecules by light microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 426-427
Author(s):  
Jeff Gelles
Keyword(s):  
Image Processing ◽  
Reaction Mechanisms ◽  
Transient State ◽  
Nanometer Scale ◽  
Reaction Intermediates ◽  
Enzyme Molecule ◽  
Directed Movement ◽  
Enzyme Molecules ◽  
Individual Enzyme ◽  
Single Reaction

Mechanoenzymes are enzymes which use a chemical reaction to power directed movement along biological polymer. Such enzymes include the cytoskeletal motors (e.g., myosins, dyneins, and kinesins) as well as nucleic acid polymerases and helicases. A single catalytic turnover of a mechanoenzyme moves the enzyme molecule along the polymer a distance on the order of 10−9 m We have developed light microscope and digital image processing methods to detect and measure nanometer-scale motions driven by single mechanoenzyme molecules. These techniques enable one to monitor the occurrence of single reaction steps and to measure the lifetimes of reaction intermediates in individual enzyme molecules. This information can be used to elucidate reaction mechanisms and determine microscopic rate constants. Such an approach circumvents difficulties encountered in the use of traditional transient-state kinetics techniques to examine mechanoenzyme reaction mechanisms.

Microstructural characterization of sol-gel coating on PET films

1994 ◽  
Vol 52 ◽  
pp. 886-887
Author(s):  
R. T. Chen ◽  
R.A. Norwood
Keyword(s):  
Ion Beam ◽  
Sol Gel ◽  
Industrial Applications ◽  
Hard Coatings ◽  
Nanometer Scale ◽  
Ion Beam Sputtering ◽  
Process Technology ◽  
Refractive Index Measurement ◽  
Organically Modified ◽  
Pet Films

Sol-gel processing has been used to control the structure of a material on a nanometer scale in preparing advanced ceramics and glasses. Film coating using the sol-gel process was also found to be a viable process technology in applications such as optical, porous, antireflection and hard coatings. In this study, organically modified silicate (Ormosil) coatings are applied to PET films for various industrial applications. Sol-gel materials are known to exhibit nanometer scale structures which havepreviously been characterized by small-angle X-ray scattering (SAXS), neutron scattering and light scattering. Imaging of the ultrafine sol-gel structures has also been performed using an ultrahigh resolution replica/TEM technique. The objective of this study was to evaluate the ultrafine structures inthe sol gel coatings using a direct imaging technique: atomic force microscopy (AFM). In addition, correlation of microstructures with processing parameters, coating density and other physical properties will be discussed.The materials evaluated are organically modified silicate coatings on PET film substrates. Refractive index measurement by the prism coupling method was used to assess density of the sol-gel coating.AFM imaging was performed on a Nanoscope III AFM (by Digital Instruments) using constant force mode. Solgel coating samples coated with a thin layer of Ft (by ion beam sputtering) were also examined by STM in order to confirm the structures observed in the contact type AFM. In addition, to compare the previous results, sol-gel powder samples were also prepared by ultrasonication followed by Pt/Au shadowing and examined using a JEOL 100CX TEM.

Rem Study of Current Effect on the Structure of Clean Si(111) Surface

1990 ◽  
Vol 48 (1) ◽  
pp. 306-307
Author(s):  
A. Yamanaka ◽  
H. Ohse ◽  
K. Yagi
Keyword(s):  
The Other ◽  
Current Direction ◽  
Clean Surface ◽  
Current Effect ◽  
Atomic Steps ◽  
Step Bunching ◽  
Terrace Width ◽  
Step Down ◽  
A Current

Recently current effects on clean and metal adsorbate surfaces have attracted much attention not only because of interesting phenomena but also because of practically importance in treatingclean and metal adsorbate surfaces [1-6]. In the former case, metals deposited migrate on the deposit depending on the current direction and a patch of the deposit expands on the clean surface [1]. The migration is closely related to the adsorbate structures and substrate structures including their anisotropy [2,7]. In the latter case, configurations of surface atomic steps depends on the current direction. In the case of Si(001) surface equally spaced array of monatom high steps along the [110] direction produces the 2x1 and 1x2 terraces. However, a relative terrace width of the two domain depends on the current direction; a step-up current widen terraces on which dimers are parallel to the current, while a step-down current widen the other terraces [3]. On (111) surface, a step-down current produces step bunching at temperatures between 1250-1350°C, while a step-up current produces step bunching at temperatures between 1050-1250°C [5].In the present paper, our REM observations on a current induced step bunching, started independently, are described.Our results are summarized as follows.(1) Above around 1000°C a step-up current induces step bunching. The phenomenon reverses around 1200 C; a step-down current induces step bunching. The observations agree with the previous reports [5].

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