In order to analyze the effects of various sizes of pyramid structure on solar cell characteristics, a pyramid structure was formed on the wafer through various etching processes. In this paper, ...etching was performed using one-step etching processes such as alkaline solution etching, reactive ion etching (RIE), and metal-assisted chemical etching (MACE), and two-step etching processes such as alkaline solution + MACE and alkaline solution + RIE. The micro-sized pyramid-structured wafers formed using the alkali solution showed higher reflectivity than nano-sized pyramid-structured wafers. Accordingly, it was expected that the characteristics of the cells fabricated with a nano-sized pyramid-structured wafer having low reflectivity would be higher than that of a micro-sized pyramid-structured wafer. However, it was confirmed that the quantum efficiency characteristics in the short wavelength region were higher in the micro-sized pyramid-structured wafers than in the nano-sized pyramid-structured wafers. To confirm the reason for this, surface characteristics were analyzed through the deposition of an emitter layer on a wafer formed in a pyramidal structure. As a result, in the case of the nano-sized pyramid-structured wafer, the sheet resistance characteristics were lower due to the increased depth of the emitter layer in comparison to the micro-sized pyramid-structured wafer. Accordingly, it was determined that the quantum efficiency was degraded as a result of the high recombination rate.
Porous polyethylene glycol terephthalate (PET) film is a kind of mesopore structure template with pore size ranging from nanometer to micrometer by chemical etching after irradiation of heavy ions. ...The etching rate is an important factor affecting the pore morphology and quality of the membrane. In this paper, four stacked PET film were irradiated with 140 MeV 32S ions at room temperature and vacuum. During chemical etching of irradiated samples, the path etching rate Vt was determined by conduction method, and the bulk etching rate Vb was determined by weighing method. The relationship between etching temperature, concentration, sensitization time, and etching rate was studied. The results show that the etching rate is exponentially correlated with the etching temperature, and increases linearly with the increase of the etching solution concentration. When the concentration of NaOH is 3 mol·L−1 and the etching temperature is 75°C, the formation of cylindrical micropores is the most favorable. The pore size of porous PET film can be adjusted, and the relationship between pore size and etching time is dnm=15nm+0.24t. This is of great significance for the preparation of nanowires with uniform size and stable properties.
Highlights
We have obtained the optimal conditions for obtaining cylindrical holes.
The relationship between the diameter of holes and etching time were determined.
The optimal etching conditions and the etching rate for preparing cylindrical pores on PET films.
As high-precision flexible printed circuit boards (FPCBs) are required in electronic products, it is necessary to study wet chemical etching to obtain precise FPCBs with a 16-
μ
m line pitch. First, ...a π-shaped FPCB model with 16-
μ
m line pitch is established using the finite element method. The evolution of the Cu etching profile and the concentration and velocity distribution of the CuCl
2
solution are then analyzed. To analyze the influence of conveyor speed and nozzle spray pressure on the Cu etching profile, wet chemical etching was tested along a horizontally conveyed line with CuCl
2
as the acid etchant. The resulting profiles were analyzed by scanning electron microscopy. The experimental results agreed well with the simulation results, and the Cu etching profile obviously depended on both the conveyor speed and nozzle spray pressure. In addition, increasing the conveyor speed under constant nozzle spray pressure (0.16 MPa or 0.17 MPa) decreased the etching depth and increased the etching factor. In particular, when the conveyor speed was set to 3.8 m/min and the nozzle spray pressure raised to 0.18 MPa, the fabricated FPCB had a line pitch of 16
μ
m, an etching depth of 7.55
μ
m, and an etching factor of 6.45. This method can aid the selection of parameters for the wet chemical etching process, enabling the future manufacture of high-precision FPCBs and complex FPCB circuits.
Monolayers of self-assembled quasi-spherical colloidal particles are essential building blocks in the field of materials science and engineering. More typically, they are used as a template for the ...fabrication of nanostructures if they serve, for instance, as a mask for deposition of new material on the surface on which particles are assembled or for etching of the material underneath; in this case, they are removed afterwards. This is what occurs in colloidal or nanosphere lithography. In some other cases, they are not used as a sacrificial material but they are incorporated in the final structure because they are inherently interesting for their properties. Independently of their specific use and application, different strategies have been devised in order to modify size and shape of colloidal particles, so as to enrich the variety of attainable patterns and to tailor the properties of the final structures and materials. In this review, we will focus on one of the most widespread methods to shape spherical colloidal particles, i.e. dry etching techniques. We will follow the development of such approaches until recent days, so as to trace an extensive panorama of the diverse parameters that can be harnessed to achieve specific morphological changes and highlight the characteristic features of the variants of this method. We will finally discuss how particles modified via dry etching can be used for patterning or can be resuspended in solvents for very diverse applications.
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•Dry etching techniques for control of size and shape of colloidal particles are examined in detail.•The influence of dry etching process parameters on particle size and morphology is illustrated.•The impact of initial particle characteristics on final morphology upon dry etching is described.•Variants of dry etching and combination with other treatments are presented.•Applications of particles modified via dry etching are discussed.
Three major types of microstructural alterations occurring under rolling contact fatigue, white etching areas (WEAs), dark etching regions (DERs) and white etching bands (WEBs), are modelled under a ...unified approach: dislocation-assisted carbon migration theory. Following our previous work on DERs and WEBs, a novel model is proposed to describe dislocation cell formation in WEAs. The proposed model yields predictions of WEAs appearance, agreeing with experimental observations. Bearing life can be estimated by the WEA appearance model. The three microstructural alterations models are combined and, for the first time, it becomes possible to predict the occurrence and the formation progress of WEAs, DERs and WEBs with a unified theory. Microstructural alteration maps are plotted as a function of number of cycles, temperature, contact pressure and stress cycle frequency. The models are validated by the experimental results reported over the last 50 years.
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The controllable growth of two-dimensional (2D) heterostructure arrays is critical for exploring exotic physics and developing novel devices, yet it remains a substantial synthetic challenge. Here we ...report a rational synthetic strategy to fabricate mosaic heterostructure arrays in monolayer 2D atomic crystals. By using a laser-patterning and an anisotropic thermal etching process, we create periodic triangular hole arrays in 2D crystals with precisely controlled size and atomically clean edges, which function as robust templates for endoepitaxial growth of another 2D crystal, to obtain monolayer mosaic heterostructures with atomically sharp heterojunction interfaces. Systematic microstructure and spectroscopic characterizations reveal periodic modulation of chemical compositions, lattice strains and electronic band gaps throughout the mosaic heterostructures. The robust growth of the monolayer mosaic heterostructures with a high level of synthetic control opens a pathway for band structure engineering and spatially modulating the potential landscapes in the atomically thin 2D crystals, establishing a designable material platform for fundamental studies and development of complex devices and integrated circuits from 2D heterostructures.
Oxidative etching in nanostructured metals and metallic oxides plays a fundamental role in numerous areas of chemical synthesis and materials processing for the semiconductor industry. An in‐depth ...understanding of the oxidative etching mechanisms is of great significance to design various fascinating nanomaterials for practical application. In situ liquid cell transmission electron microscopy (TEM) has the merits of high temporal and spatial resolutions in real‐time, and thus it can provide solid evidence directly for the dynamic evaluation of oxidative etching in nanostructured materials that occur in solution. Herein, the recent progress of oxidative etching in nanostructured metals and metallic oxides is overviewed. First, the advancements in liquid cells designs are briefly introduced for in situ TEM observation. Subsequently, in situ liquid cell TEM/STEM advances for the oxide etching mechanisms in different surface chemistry surroundings are systematically described. In addition, both the galvanic replacement and electrochemical etching reactions are also discussed. Finally, the challenges and opportunities in utilizing the in situ liquid cell TEM technique to visualize a specific dynamic oxidative etching process are proposed. This review will provide deep insights into dynamic changes in oxidative etching processes of nanostructured materials and assist in formulating design rules for developing high‐end advanced devices.
In this review, the recent progress of the oxide etching mechanisms of nanostructured metals/metallic oxides revealed by an in situ liquid cell TEM technique are systematically summarized. The challenges and opportunities for utilizing this technique to understand the oxide etching mechanisms are also discussed, aiming to offer guidance for the rational design and engineering of nanomaterials for high‐end advanced devices.
Since its inception, LEDs have slowly transitioned from traditional solid‐state lighting applications to full‐color, self‐emissive displays. Micro‐LEDs (µLEDs) are poised to become the next ...mass‐market technology for displays in lower pixel‐density, large‐area and mobile devices alongside emerging applications for high pixel‐density augmented, virtual and mixed reality. However, it is well known that µLEDs suffer from efficiency cliff – a drastic efficiency reduction as device dimension reduces with increased severity at the single digit micron scale, often attributed to material damage from reactive ion etching (RIE) that is fundamental to the process. In this paper, a first‐ever demonstration of µLED devices ranging from 45 µm down to 5 µm fabricated by the plasma‐free metal‐assisted chemical etching (MacEtch) is presented. These devices demonstrate converging external quantum efficiencies (EQE) irrespective of mesa dimension with a spread of only 3.7% without optimization. Additionally, a multi‐pronged comparison between MacEtch and RIE is provided in terms of smoothness, material damage, macroscale uniformity and throughput. These findings carry profound implications for damage‐free scaling of multi‐heterojunction III‐V optoelectronic devices, providing a pathway for high‐density, high performance top‐down fabricated µLED arrays.
MicroLEDs (µLEDs) revolutionize displays, finding applications across consumer electronics to augmented reality (AR). One of the biggest hurdles in µLED technology is the efficiency degradation with shrinking pixel‐size, due to etching damage. In this work, nearly size‐independent external quantum efficiency (EQE) achieved using the plasma‐free metal‐assisted chemical etch (MacEtch) approach is demonstrated. This breakthrough could unlocks the full potential of ultra‐high resolution µLED displays.
•Modified inductively coupled plasma etch using gas diffuser inlets and SF6 + NF3 + H2O based glass substrate etching.•Fused silica, borosilicate glass, and aluminosilicate glass high aspect ratio ...etching.•Role of reactive (chemical) versus ion flux (Physical) etching components in glass etching.•Charging and loading effect on the overall glass etching metrics.•Fused silica etch rate of >1 μm/min with smoothness of 2 Å, borosilicate etch rate of >1 μm/min with smoothness of 67 Å, aluminosilicate etch rate of 0.45 μm/min with smoothness of 4 Å.
We report on the etching of glass substrates of various compositions in a modified inductively coupled plasma – reactive ion etch (ICP-RIE) tool using SF6 as the plasma source gas and NF3 and H2O gases introduced downstream near the surface of the wafer through a diffuser gas inlet. Using this modified system, we have been able to achieve etch rates as high as 1.06 μm/min, 1.04 μm/min, and 0.45 μm/min with surface smoothness of ∼2 Å, ∼67 Å, ∼4 Å for fused silica, borosilicate glass, and aluminosilicate glass respectively after 5 min etches. We examine the role of ion flux and fluorine radicals and molecules on the etch rate and the etch smoothness. We analyze the results obtained on 41 etches through multivariate statistical analysis and use the Pearson coefficient and P-value to determine the importance of these parameters for each of the glass substrate compositions. Overall for all three glass compositions, etch rate is critically influenced by ion flux. Fluorine based radicals and molecular fragments influence both the etch rate and surface smoothness of fused silica whereas they primarily influence the surface smoothness for borosilicate glass. The large fraction of impurity atoms of Ca and Al in aluminosilicate glass form non-volatile fluorides in the etched areas and therefore the etch rate and surface smoothness of aluminosilicate glass is primarily influenced ion flux and very little by the fluorine chemistry. We also examine the role of the layout of the metal mask layer on how it influences the charging of glass substrates during etching and therefore the etch rate.
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