Black germanium produced by inductively coupled plasma etching

Schicho, S.; Jaouad, Abdelatif; Sellmer, C.; Morris, Denis; Aimez, Vincent; Arès, Richard

doi:10.1016/j.matlet.2012.12.014

Cited by 21 publications

(15 citation statements)

References 21 publications

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“…[18] In addition, it is noticeable that the pyramids were not disorderly distributed, but aligned along two orthogonal directions, which was due to the anisotropic etching under appropriate power and chamber pressure. [17] Similar structures have been observed in dry etched black Si. [21,22] The top view SEM image of the fabricated MSM PDs is shown in Figure 2d, indicating that interdigitated metal electrodes were conformally deposited on black Ge surface.…”

Section: Introductionsupporting

confidence: 71%

“…There have been intensive research efforts to fabricate black Ge by using the standard dry etching technique based on sulfur hexafluoride (SF 6 ) and chlorine (Cl 2 ) gases. [17,18] Although Pasanen et al fabricated black Ge surface by SF 6 -based inductively coupled plasma reactive ion etching (ICP-RIE), [19] the etching process was carried out at −120 °C, resulting in substantial challenges for processing. Steglich et al realized black Ge by using Cl 2 -based RIE at room temperature, but the process requires a longer etching time of 45 min.…”

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confidence: 99%

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Black Germanium Photodetector Exceeds External Quantum Efficiency of 160%

Liao

Shin

et al. 2021

Adv Materials Technologies

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Inspired by the formation of black Si, [14,15] black Ge with nanospiked structures was achieved by femtosecond laser irradiation in SF 6 environment. [16] However, optical properties of the structure were not characterized. There have been intensive research efforts to fabricate black Ge by using the standard dry etching technique based on sulfur hexafluoride (SF 6 ) and chlorine (Cl 2 ) gases. [17,18] Although Pasanen et al. fabricated black Ge surface by SF 6 -based inductively coupled plasma reactive ion etching (ICP-RIE), [19] the etching process was carried out at −120 °C, resulting in substantial challenges for processing. Steglich et al. realized black Ge by using Cl 2 -based RIE at room temperature, but the process requires a longer etching time of 45 min. [18] The extremely high absorbance of black Ge reaching 99% was experimentally obtained in the 300-1600 nm wavelength range. However, more importantly, the excellent light absorption property of black Ge has not translated into optoelectronic performance of any functional devices.In this paper, we report the demonstration and comprehensive performance characterization of black Ge-based metal-semiconductor-metal (MSM) PDs. Spike-like Ge nanostructures with optimized dimension and uniformity are formed by Cl 2 -based room-temperature standard RIE process in 2 min. Black Ge surface exhibits an optical reflection as low as 1% at a wavelength range of 1000-2000 nm. The surface is covered with aluminum oxide (Al 2 O 3 ) to reduce dark current via an atomic layer deposition (ALD). The optoelectrical properties of black Ge PDs are compared to those of the Ge PDs made on planar surface to evaluate the applicability of black Ge toward light trapping at a device level. Responsivity of black Ge MSM PDs is enhanced significantly in the NIR range of 1.5-2 µm with a slight degradation of dark current. In addition, EQE of black Ge PDs not covered with Al 2 O 3 layer is as high as 161% at 1550 nm. Therefore, our black Ge fabricated by the simple RIE process exhibits outstanding potential for efficient NIR photodetection. Results and DiscussionFigure 1 illustrates the schematic fabrication process of black Ge PDs. Detailed process is provided in Method. In short, undoped Ge substrate (n-type, resistivity > 50 Ω cm) was thoroughly cleaned by acetone, isopropyl alcohol (IPA), and DI water. The dry etching was performed in Cl 2 environment for 2 min to In this work, a viable method is demonstrated to realize high-performance germanium (Ge) photodetectors (PDs) on the nanostructured Ge surface, namely black Ge, formed by chlorine (Cl 2 ) gas-based reactive ion etching at room temperature. Black Ge surface has spike-like pyramidal structures with a width and height up to 150 and 570 nm, respectively. Average reflection of black Ge is reduced to 2% at a wavelength range from 1 to 2 µm, while that of planar Ge is ≈37%. Light absorption is strongly enhanced by the significantly reduced reflection, thereby leading to an increase in responsivity of black Ge PDs. Moreover, external...

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Section: Introductionsupporting

confidence: 71%

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confidence: 99%

Black Germanium Photodetector Exceeds External Quantum Efficiency of 160%

Liao

Shin

et al. 2021

Adv Materials Technologies

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“…Jaouad et al reported the properties of vertically aligned Ge nanoneedles. 366 In comparison with bulk Ge, the Ge nanoneedles showed a broad emission peak centered at 650 nm. The other materials include Si ower-like structures, 367 BN nanosheets, 368 PbSe nanodendrites, 369 Bi 2 S 3 urchin-like structures, 370 In(OH) 3 This journal is © The Royal Society of Chemistry 2014 nanocubes, 371 In x Ga (1Àx) N nanotips 372 and different C nanostructures.…”

Section: Printing Technologiesmentioning

confidence: 99%

Recent advances in the potential applications of bioinspired superhydrophobic materials

2014

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International audienceThis review allows to give an overview of recent advances in the potential applications of superhydrophobic materials. Such properties are characterized by extremely high water contact angle and various adhesion properties. The conception of superhydrophobic materials has been possible by studying and mimicking natural surfaces. Now, extremely various applications have emerged such as anti-icing, anti-corrosion and anti-bacteria coatings, microfluidic devices, textiles, oil/water separation, water desalination/purification, optical devices, sensors, batteries and catalysts. At least two parameters were found to be essential for application: the presence of air on superhydrophobic materials with self-cleaning properties (Cassie-Baxter state) and the robustness of the superhydrophobic properties (stability of the Cassie-Baxter state). This review will allow to researchers to envisage new ideas and to industrialists to advance in the commercialization of these materials

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“…Indeed, nanostructures with porous or rough sidewalls [ 17 ] or with high aspect ratio [ 18 ] have resulted in excessive surface recombination despite surface passivation, whereas excellent performance has been achieved using nanostructures with smooth sidewalls and only modestly increased surface area. [ 19,20 ] Germanium nanostructures have earlier been realized by nickel‐catalyzed synthesis, [ 21 ] electrochemical etching, [ 22 ] and Bosch process‐based dry etching, [ 23 ] but the morphology of the surface structures has been nonoptimized for optoelectronic applications. Additionally, previous research has been performed only on small substrate pieces, which is impractical for the manufacturing of actual devices, especially since the surface area that is exposed to the etching chemistry may affect the process.…”

Section: Figurementioning

confidence: 99%

Nanostructured Germanium with >99% Absorption at 300–1600 nm Wavelengths

Pasanen

Isometsä

Garín

et al. 2020

Advanced Optical Materials

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Near‐infrared (NIR) sensors find numerous applications within various industry fields, including optical communications and medical diagnostics. However, the state‐of‐the‐art NIR sensors made of germanium (Ge) suffer from rather poor response, largely due to high reflection from the illuminated device surface. This work demonstrates a method to increase the sensitivity of Ge sensors by implementing nanostructures to the wafer surfaces. The absorbance of nanostructured Ge wafers is measured to be >99% in the whole UV–vis–NIR spectrum up to 1600 nm wavelength, which is a significant improvement to bare Ge wafers that reach absorption of only 63% in maximum. The process is shown to be capable of producing uniform nanostructures covering full 100 mm diameter substrates as well as wafers with etch mask openings of different sizes and shapes, which demonstrates its applicability to complementary metal oxide semiconductor (CMOS) sensor manufacturing. The results imply that nanostructured Ge has potential to revolutionize the sensitivity of Ge‐based sensors.

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Black germanium produced by inductively coupled plasma etching

Cited by 21 publications

References 21 publications

Black Germanium Photodetector Exceeds External Quantum Efficiency of 160%

Black Germanium Photodetector Exceeds External Quantum Efficiency of 160%

Recent advances in the potential applications of bioinspired superhydrophobic materials

Nanostructured Germanium with >99% Absorption at 300–1600 nm Wavelengths

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