Formation of Etch Pits on Germanium Surfaces Loaded with Reduced Graphene Oxide in Water

Nakade, Kazuki; Hirano, Tomoki; Li, Shaoxian; Saito, Yûsuke; Mori, Daisuke; Morita, Mizuho; Kawai, Kentaro; Arima, Kenta

doi:10.1149/07704.0127ecst

Cited by 5 publications

(5 citation statements)

References 18 publications

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“…Nakade et al 192 investigated the use of highly-reduced graphene oxide (hrGO) as a catalyst for the MacEtch of Ge. As metal catalysts can induce surface contamination, it was suggested that a graphene oxide catalyst would allow for surface flattening via a MacEtch process without the presence of metal catalysts.…”

Section: Germaniummentioning

confidence: 99%

“…191 MacEtch of Ge substrates, which are otherwise easily damaged by many commonly used surface chemistries, may provide a means to take advantage of the attributes of Ge without confronting the issues associated with Ge surface processing. Novel approaches to Ge MacEtch have been adopted by utilizing gentle wet chemistries for catalytic etching (e.g., use of H 2 O as the primary etchant), or the employment of novel catalysts such as various reduced states of graphene, 192,193 which is intriguing as graphene is a promising next generation material for a range of devices. 194,195 Ge MacEtch results are tabulated in Table 7.…”

Section: Germaniummentioning

confidence: 99%

“…Novel approaches to Ge MacEtch have been adopted by utilizing gentle wet chemistries for catalytic etching ( e.g. , use of H 2 O as the primary etchant), or the employment of novel catalysts such as various reduced states of graphene, 192,193 which is intriguing as graphene is a promising next generation material for a range of devices. 194,195 Ge MacEtch results are tabulated in Table 7.…”

Section: Introductionmentioning

confidence: 99%

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Metal-assisted chemical etching beyond Si: applications to III–V compounds and wide-bandgap semiconductors

Znati,

Wharwood,

Tezanos

et al. 2024

Nanoscale

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Section: Germaniummentioning

confidence: 99%

Section: Germaniummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Metal-assisted chemical etching beyond Si: applications to III–V compounds and wide-bandgap semiconductors

Znati,

Wharwood,

Tezanos

et al. 2024

Nanoscale

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“…explored Si etching by using carbon allotropes such as nanotubes and nanospheres in a HF/H 2 O vapor . In our recent study, we demonstrated that the Ge surface under single sheets of reduced graphene oxide (rGO) was preferentially etched in O 2 -containing water. , Chemically modified graphene including rGO has a unique feature that allows it to be dispersed in liquid. Owing to this feature, chemical etching enhanced by a modified graphene sheet is compatible with conventional wet processes such as spray coating and lithography to form a three-dimensional structure on a semiconductor surface.…”

Section: Introductionmentioning

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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“…For example, Li et al [15] investigated the formation of Ge nanostructures by wet etching assisted by graphene. Nakade et al [16,17] employed reduced graphene oxide to boost Ge wet etching in water. However, graphene-and graphene oxide-assisted chemical etching of Ge suffer from low etch rate (20-30 nm h −1 even when heated up) and poor morphologies, which make it unsuitable for mass production of uniform nanostructures.…”

mentioning

confidence: 99%

Producing Microscale Ge Textures via Titanium Nitride‐ and Nickel‐Assisted Chemical Etching with CMOS‐Compatibility

Liao

Shin

Jin

et al. 2021

Adv Materials Inter

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on Ge has been explored as a promising alternative to traditional etching techniques. For example, Kim et al. [9] employed a thin Au layer as catalyst to realize pyramidal and indentation antireflection textures on Ge which contributed to enhance responsivity of near infrared (NIR) photodetectors. Lee et al. [10] coated a thin Ag layer on Ge and realized the formation of random antireflection structures by MacEtching in H 2 O 2 /HF/AgNO 3 solution. Shin et al. [11] also fabricated Ge nano-cone array using a thin Ag catalyst layer, followed by MacEtching in HF/H 2 O 2 .It should be emphasized that metal catalyst layer such as widely-used Au and Ag plays a crucial role for the MacEtch process of Ge, since it catalyzes the reduction of oxidant in the solution (normally H 2 O 2 and KMnO 4 ) to generate holes for subsequent etching. Although MacEtch of Ge based on those noble metal catalysts has been well explored, the usage of those noble metals is still a major drawback for the integration of Ge MacEtch in the current industrial front and back end of the line in the complementary metal oxide semiconductor (CMOS) fabrication process because deep-level defects are generated by non-CMOS compatible metals. [12][13][14] Many researchers have delved into the uncharted territory in order to identify the suitable CMOS-compatible catalyst for Ge MacEtch. For example, Li et al. [15] investigated the formation of Ge nanostructures by wet etching assisted by graphene. Nakade et al. [16,17] employed reduced graphene oxide to boost Ge wet etching in water. However, graphene-and graphene oxide-assisted chemical etching of Ge suffer from low etch rate (20-30 nm h −1 even when heated up) and poor morphologies, which make it unsuitable for mass production of uniform nanostructures. Therefore, it is worthwhile to explore novel etching catalysts with high efficiency and CMOS-compatibility.Titanium nitride (TiN) is widely used in CMOS process as local interconnects and barrier layers because it is chemically stable, [18] highly conductive, and has a work function of 4.5 eV. [19] These properties make it also suitable as the catalyst which can boost various chemical reactions. [20,21] As the pioneering work employing TiN as catalyst in wet etching, Kim et al. [22] have proven its effectiveness in the fabrication of highly ordered Si nanopillars. However, etching characteristic of TiN-MacEtch is different when compared with typical Au-MacEtch. Mass transport underneath the TiN is significantly limited due to its strong adhesion, leading to etching in area not covered by TiN, similar As an emerging anisotropic wet etching technique, metal-assisted chemical etching (MacEtch) has been widely employed for fabricating nano-and micro-structures of germanium (Ge) for potential infrared (IR) photonics and optoelectronics. However, traditional noble metal catalysts such as Au and Ag limit its application in complementary metal oxide semiconductor (CMOS) processes, as Au is considered as a detrimental deep-level impurity in Ge. In this work, the fe...

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Formation of Etch Pits on Germanium Surfaces Loaded with Reduced Graphene Oxide in Water

Cited by 5 publications

References 18 publications

Metal-assisted chemical etching beyond Si: applications to III–V compounds and wide-bandgap semiconductors

Metal-assisted chemical etching beyond Si: applications to III–V compounds and wide-bandgap semiconductors

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

Producing Microscale Ge Textures via Titanium Nitride‐ and Nickel‐Assisted Chemical Etching with CMOS‐Compatibility

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