Oxidation states of GaAs surface and their effects on neutral beam etching during nanopillar fabrication

Clifford, Thomas; Tamura, Yasuaki; Syazwan, Mohd Erman; Higo, Akio; Samukawa, Seiji

doi:10.1088/0022-3727/47/21/215203

Cited by 17 publications

(14 citation statements)

References 36 publications

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“…The parameters of the SRIM calculation are listed elsewhere 48 Table 1: Parameters used for the SRIM calculations. a-C:H layer is modelled with a density of 2.2 g/cm 3 . The type of calculation used is "Surface sputtering / Monolayer Collision Steps".…”

Section: Modellingmentioning

confidence: 99%

“…Negative-ion (NI) production in low-pressure plasma has many applications and is studied in various areas, such as microelectronics 1,2,3,4,5,6 , magnetically confined fusion 7,8 , space propulsion 9,10,11 and sources for particle accelerators 12,13,14 . NI in low pressure plasmas are usually created by dissociative attachment of electrons on molecules (volume production) 15,16,17 , but they can also be created on surfaces by the bombardment of positive ions or hyperthermal neutrals 18,19,20,21,22,23,24 .…”

Section: Introductionmentioning

confidence: 99%

“…NI in low pressure plasmas are usually created by dissociative attachment of electrons on molecules (volume production) 15,16,17 , but they can also be created on surfaces by the bombardment of positive ions or hyperthermal neutrals 18,19,20,21,22,23,24 . Volume-produced NI sources are mainly used in microelectronic 1,2,3,4,5,6 and space propulsion applications 9,10,11 while surface production of NI is employed in magnetically confined fusion devices 7,8 and sources for particle accelerators 12,13,14 . Surface production of negative-ions is also observed in sputtering processes as shown in 25,26,27. In magnetically-confined fusion devices (tokamaks), NI can be used to generate a fast neutral beam through interaction with a stripping gas target; such beam is used to heat the plasma and to implement the current drive.…”

Section: Introductionmentioning

confidence: 99%

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Negative-ion surface production in hydrogen plasmas: Determination of the negative-ion energy and angle distribution function using mass spectrometry

Dubois

Achkasov

Kogut

et al. 2016

Journal of Applied Physics

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This work focuses on the understanding of the production mechanism of negative-ions on surface in low pressure plasmas of H2/D2. The negative ions are produced on a HOPG sample (Highly Oriented Pyrolitic Graphite) negatively biased with respect to plasma potential. The negative ions created under the positive ion bombardment are accelerated towards the plasma, self-extracted and detected according to their energy and mass by a mass spectrometer placed in front of the sample. The shape of the measured Negative-Ion Energy Distribution Function (NIEDF) strongly differs from the NIEDF of the ions emitted by the sample because of the limited acceptance angle of the mass spectrometer. To get information on the production mechanisms, we propose a method to obtain the distribution functions in energy and angle (NIEADFs) of the negative-ions emitted by the sample. It is based on an a priori determination of the NIEADF and on an a posteriori validation of the choice by comparison of the modelled and experimental NIEDFs.

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Section: Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Negative-ion surface production in hydrogen plasmas: Determination of the negative-ion energy and angle distribution function using mass spectrometry

Dubois

Achkasov

Kogut

et al. 2016

Journal of Applied Physics

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“…Negativeoxygen-ion sources for secondary ion mass spectrometry operate by volume production. While plasma thrusters for space propulsion [14][15][16] and microelectronics etching plasmas [17][18][19][20][21][22] currently rely on volume production, they may also benefit in future from utilising surface production.…”

Section: Introductionmentioning

confidence: 99%

Alternative solutions to caesium in negative-ion sources: a study of negative-ion surface production on diamond in H₂/D₂ plasmas

et al. 2017

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This paper deals with a study of H − /D − negative ion surface production on diamond in low pressure H 2 /D 2 plasmas. A sample placed in the plasma is negatively biased with respect to plasma potential. Upon positive ion impacts on the sample, some negative ions are formed and detected according to their mass and energy by a mass spectrometer placed in front of the sample. The experimental methods developed to study negative ion surface production and obtain negative ion energy and angle distribution functions are first presented. Different diamond materials ranging from nanocrystalline to single crystal layers, either doped with boron or intrinsic, are then investigated and compared with graphite. The negative ion yields obtained are presented as a function of different experimental parameters such as the exposure time, the sample bias which determines the positive ion impact energy and the sample surface temperature. It is concluded from these experiments that the electronic properties of diamond materials, among them the negative electron affinity, seem to be favourable for negative-ion surface production. However, the negative ion yield decreases with the plasma induced defect density. fusion power-plant prototype producing electrical energy, targeting ∼1 GW of electrical power coupled to the grid [23,24]. In the ITER and DEMO devices, the heating of the plasma will mainly be produced by neutral beam injection (NBI). NBIs systems are key components in achieving high fusion energetic-performances. The ITER NBIs are required to inject 1 MeV beams of neutral deuterium atoms (D) into the tokamak, providing plasma heating and current drive. At such high velocities, much larger than classical electron orbit velocities of hydrogen atoms, the probability of electron capture from D + ions is too low, so that production of D relies on electron detachment from high-intensity D − beams. D − negative-ions are produced in a low-pressure plasma source and subsequently extracted and accelerated.The ITER negative ion source, currently under development at IPP Garching [7,25] in Germany, operates with a high-density, low-pressure inductively coupled plasma. Extracted D − current density of 200 A m −2 , over a large surface of 1.2 m 2 , with 5%-10% uniformity and low co-extracted electron-current (below one electron per negative ion), during long operation period (3600 s) is targeted. To reach such a high D − negative-ion current, the only up-to-date scientific solution is the use of caesium. Deuterium negative-ions are created at the extraction region by backscattering of positive ions or neutrals on the plasma grid. Deposition of caesium on the grid lowers the material work function and allows for high electron-capture efficiency by incident particles and thus, high negative ion yields. Studies conducted at IPP Garching show that the ITER negative-ion source can reach the required high current densities. However, drawbacks to the use of caesium have been identified. First, the caesium is continuously injected in the source a...

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“…Recently, we have achieved InGaN/GaN single quantum nanodisk blue emission by using fusion nanoprocessing of an iron oxide core and ferritin protein particles and damageless plasma neutral beam etching. − The optical properties of InGaN/GaN QNDs have not been fully studied yet since the higher indium content in the c -plane SQW could result in lower emission efficiency due to the strong QCSE. In this study, we present InGaN/GaN QNDs with enhanced emission intensity properties and analyze their characteristics using temperature-dependent PL, time-resolved PL, and a theoretical simulation using three-dimensional finite difference methods…”

mentioning

confidence: 99%

Optical Study of Sub-10 nm In_0.3Ga_0.7N Quantum Nanodisks in GaN Nanopillars

Higo¹,

Kiba

Chen

et al. 2017

ACS Photonics

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We have demonstrated the fabrication of homogeneously distributed In 0.3 Ga 0.7 N/GaN quantum nanodisks (QNDs) with a high density and average diameter of 10 nm or less in 30-nm-high nanopillars. The scalable top-down nanofabrication process used biotemplates that were spincoated on an In 0.3 Ga 0.7 N/GaN single quantum well (SQW) followed by low-damage dry etching on ferritins with 7 nm diameter iron cores. The photoluminescence measurements at 70 K showed a blue shift of quantum energy of 420 meV from the In 0.3 Ga 0.7 N/GaN SQW to the QND. The internal quantum efficiency of the In 0.3 Ga 0.7 N/GaN QND was 100 times that of the SQW. A significant reduction in the quantum-confined Stark effect in the QND structure was observed, which concurred with the numerical simulation using a 3D Schrodinger equation. These results pave the way for the fabrication of large-scale III− N quantum devices using nanoprocessing, which is vital for optoelectronic communication devices.

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Oxidation states of GaAs surface and their effects on neutral beam etching during nanopillar fabrication

Cited by 17 publications

References 36 publications

Negative-ion surface production in hydrogen plasmas: Determination of the negative-ion energy and angle distribution function using mass spectrometry

Negative-ion surface production in hydrogen plasmas: Determination of the negative-ion energy and angle distribution function using mass spectrometry

Alternative solutions to caesium in negative-ion sources: a study of negative-ion surface production on diamond in H₂/D₂ plasmas

Optical Study of Sub-10 nm In_0.3Ga_0.7N Quantum Nanodisks in GaN Nanopillars

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Oxidation states of GaAs surface and their effects on neutral beam etching during nanopillar fabrication

Cited by 17 publications

References 36 publications

Negative-ion surface production in hydrogen plasmas: Determination of the negative-ion energy and angle distribution function using mass spectrometry

Negative-ion surface production in hydrogen plasmas: Determination of the negative-ion energy and angle distribution function using mass spectrometry

Alternative solutions to caesium in negative-ion sources: a study of negative-ion surface production on diamond in H2/D2 plasmas

Optical Study of Sub-10 nm In0.3Ga0.7N Quantum Nanodisks in GaN Nanopillars

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Product

Resources

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Alternative solutions to caesium in negative-ion sources: a study of negative-ion surface production on diamond in H₂/D₂ plasmas

Optical Study of Sub-10 nm In_0.3Ga_0.7N Quantum Nanodisks in GaN Nanopillars