Materials

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16 pages, 7331 KiB

Open AccessFeature PaperArticle

Effect of Nanodiamond Sizes on the Efficiency of the Quasi-Specular Reflection of Cold Neutrons

by Alexei Bosak, Marc Dubois, Ekaterina Korobkina, Egor Lychagin, Alexei Muzychka, Grigory Nekhaev, Valery Nesvizhevsky, Alexander Nezvanov, Thomas Saerbeck, Ralf Schweins, Alexander Strelkov, Kylyshbek Turlybekuly and Kirill Zhernenkov

Materials 2023, 16(2), 703; https://doi.org/10.3390/ma16020703 - 11 Jan 2023

Cited by 4 | Viewed by 2272

Abstract

Nanomaterials can intensively scatter and/or reflect radiation. Such processes and materials are of theoretical and practical interest. Here, we study the quasi-specular reflections (QSRs) of cold neutrons (CNs) and the reflections of very cold neutrons (VCNs) from nanodiamond (ND) powders. The fluorination of [...] Read more.

Nanomaterials can intensively scatter and/or reflect radiation. Such processes and materials are of theoretical and practical interest. Here, we study the quasi-specular reflections (QSRs) of cold neutrons (CNs) and the reflections of very cold neutrons (VCNs) from nanodiamond (ND) powders. The fluorination of ND increased its efficiency by removing/replacing hydrogen, which is otherwise the dominant cause of neutron loss due to incoherent scattering. The probability of the diffuse reflection of VCNs increased for certain neutron wavelengths by using appropriate ND sizes. Based on model concepts of the interaction of CNs with ND, and in reference to our previous work, we assume that the angular distribution of quasi-specularly reflected CNs is narrower, and that the probability of QSRs of longer wavelength neutrons increases if we increase the characteristic sizes of NDs compared to standard detonation nanodiamonds (DNDs). However, the probability of QSRs of CNs with wavelengths below the cutoff of ~4.12 Å decreases due to diffraction scattering on the ND crystal lattice. We experimentally compared the QSRs of CNs from ~4.3 nm and ~15.0 nm ND. Our qualitative conclusions and numerical estimates can help optimize the parameters of ND for specific practical applications based on the QSRs of CNs. Full article

(This article belongs to the Special Issue Diamond Material and Its Applications)

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10 pages, 2122 KiB

Open AccessArticle

The Barrier’s Heights and Its Inhomogeneities on Diamond Silicon Interfaces

by Szymon Łoś, Kazimierz Fabisiak, Kazimierz Paprocki, Wojciech Kozera, Tomasz Knapowski, Mirosław Szybowicz and Anna Dychalska

Materials 2022, 15(17), 5895; https://doi.org/10.3390/ma15175895 - 26 Aug 2022

Cited by 1 | Viewed by 1707

Abstract

In this work, the electrical parameters of the polycrystalline diamonds’ p-PCD/n-Si heterojunction were investigated using temperature-dependent current–voltage (I-V) characteristics. In the temperature range of 80–280 K, the ideality factor (

n

) and energy barrier height (φ_b) were found to [...] Read more.

In this work, the electrical parameters of the polycrystalline diamonds’ p-PCD/n-Si heterojunction were investigated using temperature-dependent current–voltage (I-V) characteristics. In the temperature range of 80–280 K, the ideality factor (

n

) and energy barrier height (φ_b) were found to be strongly temperature dependent. The φ_b increases with temperature rise, while the n value decreases. The observed dependencies are due to imperfections at the interface region of a heterojunction and the non-homogeneous distribution of the potential barrier heights. Values of the φ_b were calculated from I-V characteristics using the thermionic emission theory (TE). The plot of φ_b versus 1/2 kT revealed two distinct linear regions with different slopes in temperature regions of 80–170 K and 170–280 K. This indicates the existence of a double Gaussian distribution (DGD) in heterojunctions. Parameters such as mean barrier heights

{\bar{φ}}_{b}

and standard deviations σ were obtained from the plots linearization and read out from intercepts and slopes. They take values

{\bar{φ}}_{b}

= 1.06 eV, σ = 0.43 eV, respectively. The modified Richardson plot is drawn to show the linear behavior in these two temperature ranges, disclosing different values of the effective Richardson constants (A*). Full article

(This article belongs to the Special Issue Diamond Material and Its Applications)

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9 pages, 2355 KiB

Open AccessArticle

Normally-off Hydrogen-Terminated Diamond Field-Effect Transistor with SnO_x Dielectric Layer Formed by Thermal Oxidation of Sn

by Shi He, Yanfeng Wang, Genqiang Chen, Juan Wang, Qi Li, Qianwen Zhang, Ruozheng Wang, Minghui Zhang, Wei Wang and Hongxing Wang

Materials 2022, 15(14), 5082; https://doi.org/10.3390/ma15145082 - 21 Jul 2022

Cited by 3 | Viewed by 2057

Abstract

SnO_x films were deposited on a hydrogen-terminated diamond by thermal oxidation of Sn. The X-ray photoelectron spectroscopy result implies partial oxidation of Sn film on the diamond surface. The leakage current and capacitance–voltage properties of Al/SnO_x/H-diamond metal-oxide-semiconductor diodes were investigated. [...] Read more.

SnO_x films were deposited on a hydrogen-terminated diamond by thermal oxidation of Sn. The X-ray photoelectron spectroscopy result implies partial oxidation of Sn film on the diamond surface. The leakage current and capacitance–voltage properties of Al/SnO_x/H-diamond metal-oxide-semiconductor diodes were investigated. The maximum leakage current density value at −8.0 V is 1.6 × 10⁻⁴ A/cm², and the maximum capacitance value is measured to be 0.207 μF/cm². According to the C–V results, trapped charge density and fixed charge density are determined to be 2.39 × 10¹² and 4.5 × 10¹¹ cm⁻², respectively. Finally, an enhancement-mode H-diamond field effect transistor was obtained with a V_TH of −0.5 V. Its I_DMAX is −21.9 mA/mm when V_GS is −5, V_DS is −10 V. The effective mobility and transconductance are 92.5 cm²V⁻¹ s⁻¹ and 5.6 mS/mm, respectively. We suspect that the normally-off characteristic is caused by unoxidized Sn, whose outermost electron could deplete the hole in the channel. Full article

(This article belongs to the Special Issue Diamond Material and Its Applications)

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7 pages, 2588 KiB

Open AccessArticle

Electrical Characteristics of Diamond MOSFET with 2DHG on a Heteroepitaxial Diamond Substrate

by Genqiang Chen, Wei Wang, Fang Lin, Minghui Zhang, Qiang Wei, Cui Yu and Hongxing Wang

Materials 2022, 15(7), 2557; https://doi.org/10.3390/ma15072557 - 31 Mar 2022

Cited by 6 | Viewed by 2828

Abstract

In this work, hydrogen-terminated diamond (H-diamond) metal-oxide-semiconductor field-effect-transistors (MOSFETs) on a heteroepitaxial diamond substrate with an Al₂O₃ dielectric and a passivation layer were characterized. The full-width at half maximum value of the diamond (004) X-ray rocking curve was 205.9 arcsec. [...] Read more.

In this work, hydrogen-terminated diamond (H-diamond) metal-oxide-semiconductor field-effect-transistors (MOSFETs) on a heteroepitaxial diamond substrate with an Al₂O₃ dielectric and a passivation layer were characterized. The full-width at half maximum value of the diamond (004) X-ray rocking curve was 205.9 arcsec. The maximum output current density and transconductance of the MOSFET were 172 mA/mm and 10.4 mS/mm, respectively. The effect of a low-temperature annealing process on electrical properties was also investigated. After the annealing process in N₂ atmosphere, the threshold voltage (V_th) and flat-band voltage (V_FB) shifts to negative direction due to loss of negative charges. After annealing at 423 K for 3 min, the maximum value of hole field effective mobility (μ_eff) increases by 27% at V_th − V_GS = 2 V. The results, which are not inferior to those based on homoepitaxial diamond, promote the application of heteroepitaxial diamond in the field of electronic devices. Full article

(This article belongs to the Special Issue Diamond Material and Its Applications)

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9 pages, 3713 KiB

Open AccessArticle

Thickness Impact on the Morphology, Strain Relaxation and Defects of Diamond Heteroepitaxially Grown on Ir/Al₂O₃ Substrates

by Ruozheng Wang, Fang Lin, Qiang Wei, Gang Niu and Hong-Xing Wang

Materials 2022, 15(2), 624; https://doi.org/10.3390/ma15020624 - 14 Jan 2022

Cited by 6 | Viewed by 2220

Abstract

This paper investigates the formation and propagation of defects in the heteroepitaxial growth of single-crystal diamond with a thick film achieving 500 µm on Ir (001)/Al₂O₃ substrate. The growth of diamond follows the Volmer–Weber mode, i.e., initially shows the islands [...] Read more.

This paper investigates the formation and propagation of defects in the heteroepitaxial growth of single-crystal diamond with a thick film achieving 500 µm on Ir (001)/Al₂O₃ substrate. The growth of diamond follows the Volmer–Weber mode, i.e., initially shows the islands and subsequently coalesces to closed films. The films’ strain imposed by the substrate gradually relaxed as the film thickness increased. It was found that defects are mainly located at the diamond/Ir interface and are then mainly propagated along the [001] direction from the nucleation region. Etching pits along the [001] direction formed by H₂/O₂ plasma treatment were used to show defect distribution at the diamond/Ir/Al₂O₃ interface and in the diamond bulk, which revealed the reduction of etching pit density in diamond thick-film surface. These results show the evident impact of the thickness on the heteroepitaxially grown diamond films, which is of importance for various device applications. Full article

(This article belongs to the Special Issue Diamond Material and Its Applications)

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6 pages, 1944 KiB

Open AccessFeature PaperArticle

HfAlO_x/Al₂O₃ Bilayer Dielectrics for a Field Effect Transistor on a Hydrogen-Terminated Diamond

by Minghui Zhang, Fang Lin, Wei Wang, Feng Wen, Genqiang Chen, Shi He, Yanfeng Wang, Shuwei Fan, Renan Bu and Hongxing Wang

Materials 2022, 15(2), 446; https://doi.org/10.3390/ma15020446 - 7 Jan 2022

Cited by 2 | Viewed by 1828

Abstract

In this work, a hydrogen-terminated (H-terminated) diamond field effect transistor (FET) with HfAlO_x/Al₂O₃ bilayer dielectrics is fabricated and characterized. The HfAlO_x/Al₂O₃ bilayer dielectrics are deposited by the atomic layer deposition (ALD) technique, which [...] Read more.

In this work, a hydrogen-terminated (H-terminated) diamond field effect transistor (FET) with HfAlO_x/Al₂O₃ bilayer dielectrics is fabricated and characterized. The HfAlO_x/Al₂O₃ bilayer dielectrics are deposited by the atomic layer deposition (ALD) technique, which can protect the H-terminated diamond two-dimensional hole gas (2DHG) channel. The device demonstrates normally-on characteristics, whose threshold voltage (V_TH) is 8.3 V. The maximum drain source current density (I_DSmax), transconductance (G_m), capacitance (C_OX) and carrier density (ρ) are −6.3 mA/mm, 0.73 mS/mm, 0.22 μF/cm² and 1.53 × 10¹³ cm⁻², respectively. Full article

(This article belongs to the Special Issue Diamond Material and Its Applications)

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10 pages, 2402 KiB

Open AccessArticle

Reducing Threading Dislocations of Single-Crystal Diamond via In Situ Tungsten Incorporation

by Ruozheng Wang, Fang Lin, Gang Niu, Jianing Su, Xiuliang Yan, Qiang Wei, Wei Wang, Kaiyue Wang, Cui Yu and Hong-Xing Wang

Materials 2022, 15(2), 444; https://doi.org/10.3390/ma15020444 - 7 Jan 2022

Cited by 10 | Viewed by 2856

Abstract

A lower dislocation density substrate is essential for realizing high performance in single-crystal diamond electronic devices. The in-situ tungsten-incorporated homoepitaxial diamond by introducing tungsten hexacarbonyl has been proposed. A 3 × 3 × 0.5 mm³ high-pressure, high-temperature (001) diamond substrate was cut [...] Read more.

A lower dislocation density substrate is essential for realizing high performance in single-crystal diamond electronic devices. The in-situ tungsten-incorporated homoepitaxial diamond by introducing tungsten hexacarbonyl has been proposed. A 3 × 3 × 0.5 mm³ high-pressure, high-temperature (001) diamond substrate was cut into four pieces with controlled experiments. The deposition of tungsten-incorporated diamond changed the atomic arrangement of the original diamond defects so that the propagation of internal dislocations could be inhibited. The SEM images showed that the etching pits density was significantly decreased from 2.8 × 10⁵ cm⁻² to 2.5 × 10³ cm⁻². The reduction of XRD and Raman spectroscopy FWHM proved that the double-layer tungsten-incorporated diamond has a significant effect on improving the crystal quality of diamond bulk. These results show the evident impact of in situ tungsten-incorporated growth on improving crystal quality and inhibiting the dislocations propagation of homoepitaxial diamond, which is of importance for high-quality diamond growth. Full article

(This article belongs to the Special Issue Diamond Material and Its Applications)

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8 pages, 3214 KiB

Open AccessArticle

Demultiplexer of Multi-Order Correlation Interference in Nitrogen Vacancy Center Diamond

by Xinghua Li, Faizan Raza, Yufeng Li, Jinnan Wang, Jinhao Wang, Hasnain Ali, Luyuan Wang, Yuan Zhao and Yanpeng Zhang

Materials 2021, 14(22), 6745; https://doi.org/10.3390/ma14226745 - 9 Nov 2021

Viewed by 1712

Abstract

We reported the second- and third-order temporal interference of two non-degenerate pseudo-thermal sources in a nitrogen-vacancy center (NV⁻). The relationship between the indistinguishability of source and path alternatives is analyzed at low temperature. In this article, we demonstrate the switching between [...] Read more.

We reported the second- and third-order temporal interference of two non-degenerate pseudo-thermal sources in a nitrogen-vacancy center (NV⁻). The relationship between the indistinguishability of source and path alternatives is analyzed at low temperature. In this article, we demonstrate the switching between three-mode bunching and frequency beating effect controlled by the time offset and the frequency difference to realize optical demultiplexer. Our experimental results suggest the advanced technique achieves channel spacing and speed of the demultiplexer of about 96% and 17 ns, respectively. The proposed demultiplexer model will have potential applications in quantum computing and communication. Full article

(This article belongs to the Special Issue Diamond Material and Its Applications)

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9 pages, 26975 KiB

Open AccessArticle

Surface Morphology and Microstructure Evolution of Single Crystal Diamond during Different Homoepitaxial Growth Stages

by Guoqing Shao, Juan Wang, Shumiao Zhang, Yanfeng Wang, Wei Wang and Hong-Xing Wang

Materials 2021, 14(20), 5964; https://doi.org/10.3390/ma14205964 - 11 Oct 2021

Cited by 10 | Viewed by 3275

Abstract

Homoepitaxial growth of step-flow single crystal diamond was performed by microwave plasma chemical vapor deposition system on high-pressure high-temperature diamond substrate. A coarse surface morphology with isolated particles was firstly deposited on diamond substrate as an interlayer under hillock growth model. Then, the [...] Read more.

Homoepitaxial growth of step-flow single crystal diamond was performed by microwave plasma chemical vapor deposition system on high-pressure high-temperature diamond substrate. A coarse surface morphology with isolated particles was firstly deposited on diamond substrate as an interlayer under hillock growth model. Then, the growth model was changed to step-flow growth model for growing step-flow single crystal diamond layer on this hillock interlayer. Furthermore, the surface morphology evolution, cross-section and surface microstructure, and crystal quality of grown diamond were evaluated by scanning electron microscopy, high-resolution transmission electron microcopy, and Raman and photoluminescence spectroscopy. It was found that the surface morphology varied with deposition time under step-flow growth parameters. The cross-section topography exhibited obvious inhomogeneity in crystal structure. Additionally, the diamond growth mechanism from the microscopic point of view was revealed to illustrate the morphological and structural evolution. Full article

(This article belongs to the Special Issue Diamond Material and Its Applications)

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