Formation of distinctive structures of GaN by inductively-coupled-plasma and reactive ion etching under optimized chemical etching conditions

Okada, Narihito; Nojima, K.; Ishibashi, Naoto; Nagatoshi, Kei; Itagaki, Norihiro; Inomoto, Ryo; Motoyama, Shin-ichi; Kobayashi, T.; Tadatomo, Kazuyuki

doi:10.1063/1.4986766

Cited by 15 publications

(13 citation statements)

References 10 publications

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“…Sapphire being much harder to etch than III-nitrides, the sidewalls of the nanorods are gradually etched laterally, thus leading to a sidewall profile being more vertical at the AlN/Al 2 O 3 interface. Such a change in sidewall profile after reaching the sapphire substrate was already observed for GaN stripe patterns aligned along the <

> and <

> directions [ 23 ].…”

Section: Resultssupporting

confidence: 53%

“…Note that in this case, the sidewall angle of nanorods etched from c-plane material is almost straight at high pressure, showing the opposite trend as the one described above in Figure 4 a–d and 5c. This has already been observed in the literature for c-plane etching of GaN nano and microstructure, and explained by an increased scattering and concentrations of species at high pressure that favours the formation of straight sidewall profile and even an undercut profile [ 23 , 24 ].…”

Section: Resultsmentioning

confidence: 68%

“…However, the resulting change in crystal symmetry led to the formations of other facets having either different inclinations or orientations. Facets having either fewer DB per Ga atom or a preferential N-terminated surface will tend to be the most stable [ 23 ]. As a result, anisotropic crystallographic characteristics of GaN semi- and non-polar plane seriously impact the etching behaviour when the chemical component is dominant.…”

Section: Resultsmentioning

confidence: 99%

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Impact of Inductively Coupled Plasma Etching Conditions on the Formation of Semi-Polar (\({11\overline{2}2}\)) and Non-Polar (\({11\overline{2}0}\)) GaN Nanorods

et al. 2020

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The formation of gallium nitride (GaN) semi-polar and non-polar nanostructures is of importance for improving light extraction/absorption of optoelectronic devices, creating optical resonant cavities or reducing the defect density. However, very limited studies of nanotexturing via dry etching have been performed, in comparison to wet etching. In this paper, we investigate the formation and morphology of semi-polar (112¯2) and non-polar (112¯0) GaN nanorods using inductively coupled plasma (ICP) etching. The impact of gas chemistry, pressure, temperature, radio-frequency (RF) and ICP power and time are explored. A dominant chemical component is found to have a significant impact on the morphology, being impacted by the polarity of the planes. In contrast, increasing the physical component enables the impact of crystal orientation to be minimized to achieve a circular nanorod profile with inclined sidewalls. These conditions were obtained for a small percentage of chlorine (Cl2) within the Cl2 + argon (Ar) plasma combined with a low pressure. Damage to the crystal was reduced by lowering the direct current (DC) bias through a reduction of the RF power and an increase of the ICP power.

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> and <

> directions [ 23 ].…”

Section: Resultssupporting

confidence: 53%

Section: Resultsmentioning

confidence: 68%

Section: Resultsmentioning

confidence: 99%

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Impact of Inductively Coupled Plasma Etching Conditions on the Formation of Semi-Polar (\({11\overline{2}2}\)) and Non-Polar (\({11\overline{2}0}\)) GaN Nanorods

et al. 2020

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“…Low etch depth has been successfully employed for InGaN/GaN devices to create photonics crystal and LED mesas with, in general, etch depths below 1um, while deep etch has been mainly focused on GaN materials and not actual devices. Hence more work is required to apply and optimize deep etch to create functional devices [16][17][18] The approach is to etch the epilayer from p-type GaN to sapphire to form individual or interconnected microchips for a micro-LED array [19]). Our purpose is to have a chip-to-chip isolation and to improve the electrical performance by reducing the metal surface and global capacitance induced by metallization contacts (pads, connection line) on n-GaN.…”

Section: Methodsmentioning

confidence: 99%

Development of Micron Sized Photonic Devices Based on Deep GaN Etching

et al. 2021

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In order to design and development efficient III-nitride based optoelectronic devices, technological processes require a major effort. We propose here a detailed review focussing on the etching procedure as a key step for enabling high date rate performances. In our reported research activity, dry etching of an InGaN/GaN heterogeneous structure was investigated by using an inductively coupled plasma reactive ion etching (ICP-RIE). We considered different combinations of etch mask (Ni, SiO2, resist), focussing on the optimization of the deep etching process. A GaN mesa process with an etching depth up to 6 µm was performed in Cl2/Ar-based plasmas using ICP reactors for LEDs dimen sions ranging from 5 to 150 µm². Our strategy was directed toward the mesa formation for vertical-type diode applications, where etch depths are relatively large. Etch characteristics were studied as a function of ICP parameters (RF power, chamber pressure, fixed total flow rate). Surface morphology, etch rates and sidewall profiles observed into InGaN/GaN structures were compared under different types of etching masks. For deep etching up to few microns into the GaN template, we state that a Ni or SiO2 mask is more suitable to obtain a good selectivity and vertical etch profiles. The optimized etch rate was about 200nm/min under moderate ICP conditions. We applied these conditions for the fabrication of micro/nano LEDs dedicated to LiFi applications.

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“…In order to fabricate elaborate nanostructure, there are several issues to be considered. First, the etching conditions must be precisely controlled 41 because the intrinsic property of dry etching process can make the ring-shaped structure slightly tapered. Second, the uniformity of the structure can be improved by using nanospheres with lower size distribution.…”

Section: Device Optimization and Fabricationmentioning

confidence: 99%

Multiple-patterning colloidal lithography-implemented scalable manufacturing of heat-tolerant titanium nitride broadband absorbers in the visible to near-infrared

Lee

Kim

et al. 2021

Microsyst Nanoeng

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Broadband perfect absorbers have been intensively researched for decades because of their near-perfect absorption optical property that can be applied to diverse applications. Unfortunately, achieving large-scale and heat-tolerant absorbers has been remained challenging work because of costly and time-consuming lithography methods and thermolability of materials, respectively. Here, we demonstrate a thermally robust titanium nitride broadband absorber with >95% absorption efficiency in the visible and near-infrared region (400–900 nm). A relatively large-scale (2.5 cm × 2.5 cm) absorber device is fabricated by using a fabrication technique of multiple-patterning colloidal lithography. The optical properties of the absorber are still maintained even after heating at the temperatures >600 ∘C. Such a large-scale, heat-tolerant, and broadband near-perfect absorber will provide further useful applications in solar thermophotovoltaics, stealth, and absorption controlling in high-temperature conditions.

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Formation of distinctive structures of GaN by inductively-coupled-plasma and reactive ion etching under optimized chemical etching conditions

Cited by 15 publications

References 10 publications

Impact of Inductively Coupled Plasma Etching Conditions on the Formation of Semi-Polar (\({11\overline{2}2}\)) and Non-Polar (\({11\overline{2}0}\)) GaN Nanorods

Impact of Inductively Coupled Plasma Etching Conditions on the Formation of Semi-Polar (\({11\overline{2}2}\)) and Non-Polar (\({11\overline{2}0}\)) GaN Nanorods

Development of Micron Sized Photonic Devices Based on Deep GaN Etching

Multiple-patterning colloidal lithography-implemented scalable manufacturing of heat-tolerant titanium nitride broadband absorbers in the visible to near-infrared

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