Chemical Etching of GaN in KOH Solution: Role of Surface Polarity and Prior Photoetching

2022 ◽  
Author(s):  
J. L. Weyher ◽  
D. H. van Dorp ◽  
T. Conard ◽  
G. Nowak ◽  
I. Levchenko ◽  
...  
Keyword(s):  
Chemical Etching ◽  
Surface Polarity

scholarly journals Metal-Assisted Chemical Etching for Anisotropic Deep Trenching of GaN Array

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3179
Author(s):  
Qi Wang ◽  
Kehong Zhou ◽  
Shuai Zhao ◽  
Wen Yang ◽  
Hongsheng Zhang ◽  
...  
Keyword(s):  
Chemical Etching ◽  
Low Cost ◽  
Etching Rate ◽  
Surface Damage ◽  
Device Fabrication ◽  
Irreversible Damage ◽  
Catalytic Role ◽  
Metal Assisted Chemical Etching ◽  
Gan Etching

Realizing the anisotropic deep trenching of GaN without surface damage is essential for the fabrication of GaN-based devices. However, traditional dry etching technologies introduce irreversible damage to GaN and degrade the performance of the device. In this paper, we demonstrate a damage-free, rapid metal-assisted chemical etching (MacEtch) method and perform an anisotropic, deep trenching of a GaN array. Regular GaN microarrays are fabricated based on the proposed method, in which CuSO4 and HF are adopted as etchants while ultraviolet light and Ni/Ag mask are applied to catalyze the etching process of GaN, reaching an etching rate of 100 nm/min. We comprehensively explore the etching mechanism by adopting three different patterns, comparing a Ni/Ag mask with a SiN mask, and adjusting the etchant proportion. Under the catalytic role of Ni/Ag, the GaN etching rate nearby the metal mask is much faster than that of other parts, which contributes to the formation of deep trenches. Furthermore, an optimized etchant is studied to restrain the disorder accumulation of excessive Cu particles and guarantee a continuous etching result. Notably, our work presents a novel low-cost MacEtch method to achieve GaN deep etching at room temperature, which may promote the evolution of GaN-based device fabrication.

Decisive role of dopants in the optical properties of vertically aligned silicon nanowires prepared by metal-assist chemical etching

2021 ◽  
Vol 121 ◽  
pp. 111632
Author(s):  
Le Thanh Cong ◽  
Nguyen Thi Ngoc Lam ◽  
Doan Van Thuong ◽  
Ngo Ngoc Ha ◽  
Nguyen Duc Dung ◽  
...  
Keyword(s):  
Optical Properties ◽  
Silicon Nanowires ◽  
Chemical Etching ◽  
Decisive Role ◽  
Vertically Aligned

Defect Etching of Non-Polar and Semi-Polar Faces in SiC

2007 ◽  
Vol 556-557 ◽  
pp. 243-246
Author(s):  
Sakwe Aloysius Sakwe ◽  
Yeon Suk Jang ◽  
Peter J. Wellmann
Keyword(s):  
Chemical Etching ◽  
Structural Defects ◽  
Surface Polarity ◽  
Applied Method ◽  
Wet Chemical ◽  
Wet Chemical Etching ◽  
Etching Parameters ◽  
Kinetics Of

Wet chemical etching using molten KOH is the most frequently applied method to reveal structural defects in SiC. Until now etching kinetics of SiC in planes different from the polar cplane has not been reported. In this paper we report on defect etching of SiC in non-polar faces. Using a calibrated KOH defect-etching furnace with possibilities to set accurate etching temperatures we have etched SiC samples of various orientations to (i) study defect occurrence and their morphologies (ii) set KOH defect etching parameters for SiC for these orientations and (iii) investigate etching kinetics in relation to anisotropy/surface polarity. For non-polar planes of the same orientations a comparison in etching kinetics and defect morphologies in crystals grown in different directions is presented.

Role of surface mechanical attrition treatment and chemical etching on plasma nitriding behavior of AISI 304L steel

2016 ◽  
Vol 304 ◽  
pp. 413-424 ◽  
Author(s):  
Atul M. Gatey ◽  
Santosh S. Hosmani ◽  
Carlos A. Figueroa ◽  
Shashi B. Arya ◽  
Rajkumar P. Singh
Keyword(s):  
Chemical Etching ◽  
Plasma Nitriding ◽  
Surface Mechanical Attrition Treatment ◽  
Aisi 304L ◽  
Mechanical Attrition ◽  
304L Steel

The generation of cell surface polarity in mouse 8-cell blastomeres: the role of cortical microfilaments analysed using cytochalasin D

Development ◽  
1986 ◽  
Vol 95 (1) ◽  
pp. 169-191
Author(s):  
T. P. Fleming ◽  
S. J. Pickering ◽  
F. Qasim ◽  
B. Maro
Keyword(s):  
Cell Surface ◽  
Alternative Model ◽  
Cytochalasin D ◽  
Apical Surface ◽  
Surface Polarity ◽  
Cell Cycles ◽  
Contact Areas ◽  
Microfilament System

The mechanism by which a surface pole of microvilli is generated in mouse 8-cell blastomeres has been investigated. 4-cell and 8-cell embryos (or cell couplets) were incubated for precise times during their respective cell cycles in medium containing cytochalasin D (CCD) to disrupt the microfilament system. The blastomeres were analysed immediately for the distribution and state of organization of their microvilli, using three morphological techniques. The results indicate that the surface pole, characterized by microvilli containing CCD-resistant core filaments, is not generated by the gradual segregation of stable microvilli to the apical surface. An alternative model is proposed, based upon (a) the stabilization of the apical cytocortex prior to the elongation of apical microvilli and (b) the destabilization of cytocortical elements in contact areas and the shortening and loss of basolateral microvilli.

Regulation of epithelial cell surface polarity reversal by beta 1 integrins

1994 ◽  
Vol 107 (3) ◽  
pp. 561-576 ◽  
Author(s):  
G.K. Ojakian ◽  
R. Schwimmer
Keyword(s):  
Extracellular Matrix ◽  
Cell Surface ◽  
Outer Membrane ◽  
Collagen Gel ◽  
Polarity Reversal ◽  
Integrin Subunit ◽  
Membrane Remodeling ◽  
Surface Polarity ◽  
Beta 1 Integrin

The role of extracellular matrix in the regulation of epithelial cell surface polarity development was studied using MDCK cells. Previous work has demonstrated that MDCK cells cultured in suspension form epithelial cysts having polarized cell surface distributions of several membrane proteins. When MDCK suspension cysts are incubated within collagen gel, a dynamic epithelial membrane remodeling occurs that is accompanied by the reversal of cell surface polarity (Wang et al., 1990b, J. Cell Sci. 95, 153–165), suggesting that extracellular matrix is important in the modulation of epithelial polarity development. To determine if members of the integrin receptor family were involved, MDCK cyst binding studies were done utilizing antifunctional monoclonal antibodies (AIIB2 and AJ2) against the beta 1 integrin subunit. These antibodies inhibited cyst binding to type I collagen, type IV collagen and laminin, providing evidence that functional beta 1 integrin heterodimers were present on the cyst outer membrane. Integrin localization on suspension cysts demonstrated that the alpha 2, alpha 3 and alpha 6 integrin subunits had a non-polarized cell surface distribution and were localized to both the apical and basolateral membranes. Interestingly, immunofluorescence microscopy determined that the beta 1 subunit had a polarized, basolateral membrane distribution although cyst binding studies using inhibitory monoclonal antibodies suggested that functional beta 1 subunits were present on the cyst outer membrane. After incubation of suspension cysts in collagen gel for 8 hours, the beta 1 integrin subunit was detected on the outer membrane, suggesting that the formation of additional integrin alpha/beta heterodimers could be involved in epithelial remodeling. To establish the role of beta 1 integrins in polarity reversal, experiments were done on cysts incubated in collagen gel. After 6 hours in collagen gel, considerable membrane remodeling had occurred as determined by a reduction in outer membrane microvilli. However, the presence of monoclonal antibody AIIB2 inhibited membrane remodeling by preventing both microvillar loss and the endocytosis of the apical membrane glycoprotein gp135. These results provide strong evidence that members of the beta 1 integrin family are involved in the regulation of epithelial polarity reversal, and demonstrate that MDCK cysts constitute an excellent model system for studying the role of cell-extracellular matrix interactions in the regulation of epithelial plasticity and cell surface polarity development.

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