Chemical etching of silicon assisted by graphene oxide

Kubota, Wataru; Ishizuka, Ryuko; Utsunomiya, Toru; Ichii, Takashi; Sugimura, Hiroyuki

doi:10.7567/1347-4065/ab17f3

Cited by 15 publications

(21 citation statements)

References 29 publications

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“…8−10 Previously, we demonstrated that graphene oxide (GO) works as a catalyst for the etching reaction in an HF−H 2 O 2 system. 16 GO has a graphene-like structure partially modified with oxygen functional groups (epoxy, hydroxy, and carboxy groups) and is synthesized by graphite oxidation in a costeffective manner when compared with catalysts such as noble metals and graphene. GO sheets can be dispersed in some solvents owing to the oxygen functional groups, enabling GO to be easily deposited on the substrate by a solution process.…”

Section: ■ Introductionmentioning

confidence: 99%

Chemical Etching of Silicon Assisted by Graphene Oxide in an HF–HNO₃ Solution and Its Catalytic Mechanism

et al. 2021

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Chemical etching of silicon assisted by various types of carbon materials is drawing much attention for the fabrication of silicon micro/nanostructures. We developed a method of chemical etching of silicon that utilizes graphene oxide (GO) sheets to promote the etching reaction in a hydrofluoric acid–nitric acid (HF–HNO3) etchant. By using an optimized composition of the HF–HNO3 etchant, the etching rate under the GO sheets was 100 times faster than that of our HF–H2O2 system used in a previous report. Kinetic analyses showed that the activation energy of the etching reaction was almost the same at both the bare silicon and GO-covered areas. We propose that adsorption sites for the reactant in the GO sheets enhance the reaction frequency, leading to a deeper etching in the GO areas than the bare areas. Furthermore, GO sheets with more defects were found to have higher catalytic activities. This suggests that defects in the GO sheets function as adsorption sites for the reactant, thereby enhancing the etching rate under the sheets.

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Section: ■ Introductionmentioning

confidence: 99%

Chemical Etching of Silicon Assisted by Graphene Oxide in an HF–HNO₃ Solution and Its Catalytic Mechanism

et al. 2021

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“…Consequently, it was assumed that an etching rate of Ge under an initial GO sheet was low at the beginning, and then increased gradually to reach a value similar to that of hyd -rGO in 3 h of immersion into O 2 -containing water. Such a variation of etching rates during GO-assisted etching has been reported by another group using a Si substrate in a mixed solution of H 2 O 2 /HF …”

Section: Resultsmentioning

confidence: 99%

Catalytic Properties of Chemically Modified Graphene Sheets to Enhance Etching of Ge Surface in Water

et al. 2020

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We examined chemical etching of the Ge surface assisted by single sheets of chemically modified graphene in O2-containing water. Three types of graphene sheets were used: graphene oxide (GO), hydrazine-reduced GO (hyd-rGO), and hydrothermally treated GO in an ammonia solution (amm-rGO). amm-rGO possessing pyridinic-N atoms produced the highest etching rates of the graphene used for all water temperatures tested. We propose that graphene sheets catalyze Ge oxidation underneath the sheets and that this phenomenon probably originates from the enhanced adsorption of O2 molecules in water at local defects, such as graphene edges and carbon atoms next to pyridinic-N, in the sheets. Because O2 adsorption is the initial step of either the oxygen reduction reaction or direct oxidation, it results in the formation of soluble GeO2 at the graphene/Ge interface, leaving etched hollows under the sheets. In addition, we combined graphene-assisted chemical etching with lithography by using photoresist to fabricate a trench pattern on Ge.

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“…Similarly, various carbon-based catalyst has been applied for the MaCE of Si. [98][99][100][101] These carbonaceous catalysts can be easily and cleanly removed from the Si by oxygen plasma. Another beneficial feature of carbon-based catalysts is the low light reflectance after the etching of Si, thanks to the lower reflectance of carbon materials than that of typical noble metal catalysts.…”

Section: Metal Catalystsmentioning

confidence: 99%

“…[72][73][74] A porous Si layer on n-Si was formed when the n-Si was in contact with Au and illuminated in an HF solution containing oxygen with no external bias. The formation of light-emitting porous Si was observed by introducing metal nanoparticles (Au, Pt, or Au/Pd) to Si (100) surfaces prior to immersion in the HF-H 2 O 2 aqueous solution. [75] The metal enhances (or, catalyzes) Si etching and results in the simple and efficient production of luminescent porous Si in a method, called "metal-assisted chemical etching.…”

Section: Introductionmentioning

confidence: 99%

Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

Srivastava

Khang

2021

Advanced Materials

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classified into two common approaches: bottom-up chemical synthesis, such as vapor-liquid-solid growth, [16][17][18][19][20] and topdown fabrication schemes. [21][22][23] This review will focus on the top-down fabrication of Si structures using a wet chemical etching technique aided with a metal catalyst, called metal-assisted chemical etching (MaCE). [24][25][26][27][28][29][30][31][32] In comparison with top down fabrication methods based on dry etching using a reactive plasma in vacuum, MaCE is less expensive and less complex. [33][34][35] MaCE is a nano-scale reductionoxidation (redox) process that usually occurs in aqueous solution where the sample to be etched is in contact with the etchant. MaCE is a simple, cost-effective, and versatile method to produce Si nanostructures; due to these attractive features, there have been many good review articles published on the process. [36][37][38][39][40][41][42] With two-decades of research of the MaCE and its innovative variations, recent studies have focused on the various applications of Si nanostructures prepared by MaCE, including photovoltaics, [43,44] thermoelectrics and piezoelectric nanogenerators, [45] energy storage, [46][47][48] nanophotonics and optoelectronics, [49] and biosensors and biomedical applications. [50][51][52] In this review, we provide an overview of the recent advances in MaCE processes and their novel applications. To differentiate this review from previous review articles, the main emphasis is on the recently developed novel MaCE processes and the macroscale structuring of Si by MaCE. We begin the review by describing new MaCE processes, particularly catalysts for MaCE. In contrast to well-known noble metal catalysts, such as Ag, Au, and Pt, carbon-based catalysts, such as graphene, graphene oxide, and carbon nanotubes, have been successfully applied as catalysts for MaCE. In addition, TiN has been found to be a catalyst for MaCE, making the whole process CMOS-compatible. Different types of etch additives, such as various alcohols and chlorides, have also been discussed, which enhance etch uniformity by increasing the wettability of etchants and suppressing the random diffusion of excessive (holes) h + by trapping them for better etch control. Recent novel variations of the MaCE process have been introduced, such as MaCE with externally applied electric or magnetic fields. The external field has a profound effect on the output of MaCE, by controlling the etch directionality and etch rate. In addition, MaCE can be combined with unconventional patterning techniques, StructuringSi, ranging from nanoscale to macroscale feature dimensions, is essential for many applications. Metal-assisted chemical etching (MaCE) has been developed as a simple, low-cost, and scalable method to produce structures across widely different dimensions. The process involves various parameters, such as catalyst, substrate doping type and level, crystallography, etchant formulation, and etch additives. Careful optimization of these parameters is the key to the succe...

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Chemical etching of silicon assisted by graphene oxide

Cited by 15 publications

References 29 publications

Chemical Etching of Silicon Assisted by Graphene Oxide in an HF–HNO₃ Solution and Its Catalytic Mechanism

Chemical Etching of Silicon Assisted by Graphene Oxide in an HF–HNO₃ Solution and Its Catalytic Mechanism

Catalytic Properties of Chemically Modified Graphene Sheets to Enhance Etching of Ge Surface in Water

Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

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Chemical etching of silicon assisted by graphene oxide

Cited by 15 publications

References 29 publications

Chemical Etching of Silicon Assisted by Graphene Oxide in an HF–HNO3 Solution and Its Catalytic Mechanism

Chemical Etching of Silicon Assisted by Graphene Oxide in an HF–HNO3 Solution and Its Catalytic Mechanism

Catalytic Properties of Chemically Modified Graphene Sheets to Enhance Etching of Ge Surface in Water

Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

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Chemical Etching of Silicon Assisted by Graphene Oxide in an HF–HNO₃ Solution and Its Catalytic Mechanism

Chemical Etching of Silicon Assisted by Graphene Oxide in an HF–HNO₃ Solution and Its Catalytic Mechanism