Formation of three‐dimensional GaAs microstructures by combination of wet and metal‐assisted chemical etching

Lee, A Ri; Kim, Jungkil; Choi, Suk‐Ho; Shin, Jae Cheol

doi:10.1002/pssr.201409046

Cited by 10 publications

(14 citation statements)

References 27 publications

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“…It is worth noting that GaAs NWs formed by AICE do not exhibit any tapered morphology, unlike GaAs nanostructures formed by conventional MACE methods. − , Tapering of GaAs NWs occurs only when AICE is performed using an HF electrolyte containing a small amount of an oxidant. For example, tapered GaAs NWs can be fabricated by performing AICE using an aqueous mixture solution of HF and H 2 O 2 (0.2 M H 2 O 2 /28.4 M HF, v/v = 1/80) (Figure e).…”

Section: Resultsmentioning

confidence: 99%

Anodically Induced Chemical Etching of GaAs Wafers for a GaAs Nanowire-Based Flexible Terahertz Wave Emitter

Shin

Rhu

Ji³

et al. 2020

ACS Appl. Mater. Interfaces

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A generic top-down approach for the preparation of extended arrays of high-aspect ratio GaAs nanowires (NWs) with different crystallographic orientations (i.e., [100] or [111]) and morphologies (i.e., porous, nonporous, tapered, or awl-like NWs) is reported. The method is based on the anodically induced chemical etching (AICE) of GaAs wafers in an oxidant-free aqueous HF solution at room temperature by using a patterned metal mesh and allows us to overcome the drawbacks of conventional metal-assisted chemical etching (MACE) processes. Local oxidative dissolution of GaAs in contact with a metal is achieved by externally injecting holes (h + ) into the valence band (VB) of GaAs through the metal mesh. It is found that injection of holes (h + ) through direct GaAs contact, rather than the metal mesh, does not yield uniform nanowires but porosify GaAs wafers due to the high cell potential. On the basis of experiments and numerical simulation for the spatial distribution of an electric field, a phenomenological model that explains the formation of GaAs NWs and their porosification behaviors is proposed. GaAs NWs exhibit excellent terahertz (THz) wave emission properties, which vary with either the length or the shape of the nanowires. By taking advantage of controlled porosification and easy transfer of GaAs NWs to foreign substrates, a flexible THz wave emitter is realized.

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Section: Resultsmentioning

confidence: 99%

Anodically Induced Chemical Etching of GaAs Wafers for a GaAs Nanowire-Based Flexible Terahertz Wave Emitter

Shin

Rhu

Ji³

et al. 2020

ACS Appl. Mater. Interfaces

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“…The MaCE can also be applied to semiconductors other than Si, such as Ge, [146][147][148] GaAs, [149][150][151][152][153][154][155][156][157][158][159][160][161][162][163][164] Al x Ga 1−x As, [165] GaN, [166,167] GaP, [168] InP, [169][170][171][172] SiC, [173,174] and Ga 2 O 3 [175] to fabricate various nanostructures. These compound semiconductors find widespread applications in electronics, optoelectronics, and photovoltaics, etc.…”

Section: Mace Of Semiconductors Other Than Simentioning

confidence: 99%

“…In addition to UV illumination, [156,175] the type of MaCE, either forward or inverse, can be controlled by temperature, [151,154] metal shape such as isolated disc or interconnected mesh, [147,168] or inert oxide formation at the interface between metal and semiconductor. [171,172] The etch temperature affects the etch rate, or the consumption rate of injected h + .…”

Section: Mace Of Semiconductors Other Than Simentioning

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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“…Then, the substrate can be structured by patterned metal films [32,33] or etched randomly using dispersed metallic particles [24]. In recent years, several attempts aimed to extend MacEtch to III-V group semiconductors [32][33][34][35][36][37][38][39][40][41][42][43], which yield better device characteristics in light emitting diodes and solar cells compared to mainstream silicon and germanium [44,45]. GaAs structuring via MacEtch has been reported in conjunction with catalyst vacuum depositions [46], or with metal patterning [32][33][34][35][36][37][38][39][40][41] by nanoimprint lithography [47], photolithography [20], and microsphere self-assembly [48].…”

Section: Introductionmentioning

confidence: 99%

“…with metal patterning [32][33][34][35][36][37][38][39][40][41] by nanoimprint lithography [47], photolithography [20], and microsphere self-assembly [48]. While lithographic depositions allow highly controlled nanostructuring, they have limited room for scaling-up the fabrication.…”

Section: Introductionmentioning

confidence: 99%

Black GaAs: Gold-Assisted Chemical Etching for Light Trapping and Photon Recycling

Lova

Soci

2020

Micromachines

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Thanks to its excellent semiconductor properties, like high charge carrier mobility and absorption coefficient in the near infrared spectral region, GaAs is the material of choice for thin film photovoltaic devices. Because of its high reflectivity, surface microstructuring is a viable approach to further enhance photon absorption of GaAs and improve photovoltaic performance. To this end, metal-assisted chemical etching represents a simple, low-cost, and easy to scale-up microstructuring method, particularly when compared to dry etching methods. In this work, we show that the etched GaAs (black GaAs) has exceptional light trapping properties inducing a 120 times lower surface reflectance than that of polished GaAs and that the structured surface favors photon recycling. As a proof of principle, we investigate photon reabsorption in hybrid GaAs:poly (3-hexylthiophene) heterointerfaces.

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Formation of three‐dimensional GaAs microstructures by combination of wet and metal‐assisted chemical etching

Cited by 10 publications

References 27 publications

Anodically Induced Chemical Etching of GaAs Wafers for a GaAs Nanowire-Based Flexible Terahertz Wave Emitter

Anodically Induced Chemical Etching of GaAs Wafers for a GaAs Nanowire-Based Flexible Terahertz Wave Emitter

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

Black GaAs: Gold-Assisted Chemical Etching for Light Trapping and Photon Recycling

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