Pub Date : 2026-01-23DOI: 10.1016/j.vacuum.2026.115134
Mikhail Popov , Pavel Pivovarov , Fedor Khorobrykh , Dmitry Sovyk , Victor Ralchenko
A comparative study of the wettability of ultrahard amorphous carbon (UAC), formed by sp3 bonds alone, and diamond (100) facets, has been performed experimentally using atomic force spectroscopy. The capillary forces for UAC and diamond are found to be similar within the 10 % measurement error. Based on a relationship between the capillary force and the contact angle for the substrates, it is concluded that the contact angles for hydrogenated diamond (81°) and ultrahard amorphous sp3 carbon are close.
{"title":"Similar wettability of ultrahard sp3-bonded amorphous carbon and diamond (100) revealed by atomic force spectroscopy","authors":"Mikhail Popov , Pavel Pivovarov , Fedor Khorobrykh , Dmitry Sovyk , Victor Ralchenko","doi":"10.1016/j.vacuum.2026.115134","DOIUrl":"10.1016/j.vacuum.2026.115134","url":null,"abstract":"<div><div>A comparative study of the wettability of ultrahard amorphous carbon (UAC), formed by sp<sup>3</sup> bonds alone, and diamond (100) facets, has been performed experimentally using atomic force spectroscopy. The capillary forces for UAC and diamond are found to be similar within the 10 % measurement error. Based on a relationship between the capillary force and the contact angle for the substrates, it is concluded that the contact angles for hydrogenated diamond (81°) and ultrahard amorphous sp<sup>3</sup> carbon are close.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115134"},"PeriodicalIF":3.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-23DOI: 10.1016/j.vacuum.2026.115131
Chao-Wei Huang , Sheng-Wen Liu , Wai-Cheng Lien , Yueh-Heng Li
This study presents the development and extended operational testing of a Coaxial Pulsed Plasma Thruster (CPPT) specifically designed for small satellite propulsion applications. The annular ignition system demonstrated highly stable performance over 38,000 firing cycles, while the thruster itself underwent over 100,000 discharge cycles at a capacitor discharge energy of 18.4 J, achieving a maximum thrust efficiency of 37 %. Fast Faraday Cup diagnostics revealed that the plasma plume was primarily confined between −30° and 0°, and high-speed imaging confirmed that the plume direction varied with ignition location. Thrust measurements using a hanging pendulum thrust stand indicated impulse bits of 181 μN s or 134 μN s, depending on the discharge waveform characteristics. Experimental analysis showed that using 304 stainless steel as both the cathode and ignition electrode material enabled reliable ignition under vacuum conditions. Although visible metallic powder deposition was observed on the surface of the polytetrafluoroethylene (PTFE) propellant, it did not significantly degrade thruster performance, as evidenced by sustained arc discharge stability and minimal electrode erosion. Overall, the CPPT exhibited low ablation rates and high operational efficiency, highlighting its strong potential as a long-lifetime, low-power propulsion system for microsatellites and other space missions.
{"title":"Electrode material selection and plasma-surface interactions in a coaxial pulsed plasma thruster","authors":"Chao-Wei Huang , Sheng-Wen Liu , Wai-Cheng Lien , Yueh-Heng Li","doi":"10.1016/j.vacuum.2026.115131","DOIUrl":"10.1016/j.vacuum.2026.115131","url":null,"abstract":"<div><div>This study presents the development and extended operational testing of a Coaxial Pulsed Plasma Thruster (CPPT) specifically designed for small satellite propulsion applications. The annular ignition system demonstrated highly stable performance over 38,000 firing cycles, while the thruster itself underwent over 100,000 discharge cycles at a capacitor discharge energy of 18.4 J, achieving a maximum thrust efficiency of 37 %. Fast Faraday Cup diagnostics revealed that the plasma plume was primarily confined between −30° and 0°, and high-speed imaging confirmed that the plume direction varied with ignition location. Thrust measurements using a hanging pendulum thrust stand indicated impulse bits of 181 μN s or 134 μN s, depending on the discharge waveform characteristics. Experimental analysis showed that using 304 stainless steel as both the cathode and ignition electrode material enabled reliable ignition under vacuum conditions. Although visible metallic powder deposition was observed on the surface of the polytetrafluoroethylene (PTFE) propellant, it did not significantly degrade thruster performance, as evidenced by sustained arc discharge stability and minimal electrode erosion. Overall, the CPPT exhibited low ablation rates and high operational efficiency, highlighting its strong potential as a long-lifetime, low-power propulsion system for microsatellites and other space missions.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115131"},"PeriodicalIF":3.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High Entropy alloys (HEAs) have recently emerged as promising candidates for thermoelectric applications due to their tunable transport properties enabled by entropy engineering. In this work, we investigate the effect of entropy engineering on the thermal and electrical transport properties of CoCrFeNi system through Ag alloying. The CoCrFeNiAg0.2 alloy exhibited a low lattice thermal conductivity of ∼1.34 Wm−1K−1 at 700 K, which is ∼8.6 times lower than that of the parent alloy, attributed to severe lattice distortions induced by mass and size disorder. All the HEA compositions displayed rare p-type conduction. Notably, the CoCrFeNiAg0.1 showed the highest Seebeck coefficient of ∼17.5 μVK−1, representing a 44.6 % enhancement over the reference alloy, along with the highest power factor of 213 μWm−1K−2 at 700 K. These results demonstrate that entropy-driven atomic disorder is an effective strategy to suppress phonon transport and enhance the thermoelectric performance in metallic HEAs.
{"title":"Entropy engineered p-type Ag-alloyed CoCrFeNi metallic high entropy alloys with low lattice thermal conductivity","authors":"K. Arun , Kowsalya Senthil Kumar , Navaneethan Mani , Senthil Kumar Eswaran","doi":"10.1016/j.vacuum.2026.115130","DOIUrl":"10.1016/j.vacuum.2026.115130","url":null,"abstract":"<div><div>High Entropy alloys (HEAs) have recently emerged as promising candidates for thermoelectric applications due to their tunable transport properties enabled by entropy engineering. In this work, we investigate the effect of entropy engineering on the thermal and electrical transport properties of CoCrFeNi system through Ag alloying. The CoCrFeNiAg<sub>0.2</sub> alloy exhibited a low lattice thermal conductivity of ∼1.34 Wm<sup>−1</sup>K<sup>−1</sup> at 700 K, which is ∼8.6 times lower than that of the parent alloy, attributed to severe lattice distortions induced by mass and size disorder. All the HEA compositions displayed rare <em>p</em>-type conduction. Notably, the CoCrFeNiAg<sub>0.1</sub> showed the highest Seebeck coefficient of ∼17.5 μVK<sup>−1</sup>, representing a 44.6 % enhancement over the reference alloy, along with the highest power factor of 213 μWm<sup>−1</sup>K<sup>−2</sup> at 700 K. These results demonstrate that entropy-driven atomic disorder is an effective strategy to suppress phonon transport and enhance the thermoelectric performance in metallic HEAs.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115130"},"PeriodicalIF":3.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.vacuum.2026.115106
E. Ermakova , A. Plehanov , A. Saraev , E. Gerasimov , V. Shayapov , E. Maksimovskiy , V. Sulyaeva , A. Kolodin , M. Kosinova
Hydrogenated silicon carbonitride (SiCxNy:H) films have received much attention for applications in microelectronics, particularly as interlayer dielectrics and copper diffusion barriers. However, the demonstrated properties are crucially dependent on the elemental composition and chemical bonding structure. Thus, precise control over the type of precursors and deposition conditions is necessary for the development of efficient experimental procedure. In this study, SiCxNy:H films were deposited at 200–450 °C by plasma-enhanced chemical vapor deposition (PECVD) using hexamethyldisilane (HMDS, Me3Si–SiMe3) in mixtures with nitrogen or ammonia, as well as hexamethyldisilazane (HMDSN, Me3Si–NH–SiMe3) with helium. The motivation is to establish a fundamental correlation between the plasma chemistry, driven by different nitrogen sources (N2, NH3, or the amine group in HMDSN), and film properties. Under low-power conditions the three distinct series of non-porous materials, characterized as Si–C-type and two Si–N-type, were obtained. Refractive index and dielectric constant changed in the range of 1.62–1.99 and 3.8–5.4, respectively, were related to the deposition conditions and chemical composition of the films. Transmittance electron microscopy (TEM) investigation showed the films are suitable as diffusion barriers for Cu/low-k damascene integration.
{"title":"Amorphous SiCxNy:H thin films produced with various nitrogen sources: A comparative study","authors":"E. Ermakova , A. Plehanov , A. Saraev , E. Gerasimov , V. Shayapov , E. Maksimovskiy , V. Sulyaeva , A. Kolodin , M. Kosinova","doi":"10.1016/j.vacuum.2026.115106","DOIUrl":"10.1016/j.vacuum.2026.115106","url":null,"abstract":"<div><div>Hydrogenated silicon carbonitride (SiC<sub>x</sub>N<sub>y</sub>:H) films have received much attention for applications in microelectronics, particularly as interlayer dielectrics and copper diffusion barriers. However, the demonstrated properties are crucially dependent on the elemental composition and chemical bonding structure. Thus, precise control over the type of precursors and deposition conditions is necessary for the development of efficient experimental procedure. In this study, SiC<sub>x</sub>N<sub>y</sub>:H films were deposited at 200–450 °C by plasma-enhanced chemical vapor deposition (PECVD) using hexamethyldisilane (HMDS, Me<sub>3</sub>Si–SiMe<sub>3</sub>) in mixtures with nitrogen or ammonia, as well as hexamethyldisilazane (HMDSN, Me<sub>3</sub>Si–NH–SiMe<sub>3</sub>) with helium. The motivation is to establish a fundamental correlation between the plasma chemistry, driven by different nitrogen sources (N<sub>2</sub>, NH<sub>3</sub>, or the amine group in HMDSN), and film properties. Under low-power conditions the three distinct series of non-porous materials, characterized as Si–C-type and two Si–N-type, were obtained. Refractive index and dielectric constant changed in the range of 1.62–1.99 and 3.8–5.4, respectively, were related to the deposition conditions and chemical composition of the films. Transmittance electron microscopy (TEM) investigation showed the films are suitable as diffusion barriers for Cu/low-k damascene integration.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115106"},"PeriodicalIF":3.9,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.vacuum.2026.115132
G. Yu Yushkov, V.D. Gridilev, A.G. Nikolaev, E.M. Oks
We present the results of our experiments of specific erosion of 13 different cathode materials in a microsecond pulsed vacuum arc with current 200 A. The specific erosion of materials with relatively high melting points, greater than Тmelt = 650 °C for magnesium, was found to lie within the range from 30 to 100 μg/C, which is typical of erosion in vacuum arc cathode spots. For materials with low melting points, below Тmelt = 328 °C for lead, anomalously high specific erosion in the range from 500 to 1000 μg/C was observed. We find that this high erosion is due to the contribution of a microdroplet component to the erosion products from vacuum arc cathode spots, when the cathode surface melts to the depth of tens of micrometers during the arc pulse and splashing of the melt due to electro explosive processes in the cathode spots.
{"title":"Erosion of cathode materials with different melting points in a pulsed vacuum arc","authors":"G. Yu Yushkov, V.D. Gridilev, A.G. Nikolaev, E.M. Oks","doi":"10.1016/j.vacuum.2026.115132","DOIUrl":"10.1016/j.vacuum.2026.115132","url":null,"abstract":"<div><div>We present the results of our experiments of specific erosion of 13 different cathode materials in a microsecond pulsed vacuum arc with current 200 A. The specific erosion of materials with relatively high melting points, greater than <em>Т</em><sub>melt</sub> = 650 °C for magnesium, was found to lie within the range from 30 to 100 μg/C, which is typical of erosion in vacuum arc cathode spots. For materials with low melting points, below <em>Т</em><sub>melt</sub> = 328 °C for lead, anomalously high specific erosion in the range from 500 to 1000 μg/C was observed. We find that this high erosion is due to the contribution of a microdroplet component to the erosion products from vacuum arc cathode spots, when the cathode surface melts to the depth of tens of micrometers during the arc pulse and splashing of the melt due to electro explosive processes in the cathode spots.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115132"},"PeriodicalIF":3.9,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.vacuum.2026.115127
Wei-Chih Chang
Room-temperature exchange bias (EB) in Mn-based noncollinear antiferromagnets has drawn increasing attention for spintronic applications. However, in D019-Mn3Ga/CoFeB system, the EB effect is usually restricted to low temperatures. Here, we demonstrate that introducing a Ru seed layer enables a tunable and anisotropic EB at room temperature. Interfacial strain induced by the Ru layer modulates the lattice symmetry and reconfigures the Dzyaloshinskii-Moriya interaction (DMI). These strain-mediated modifications promote the formation of nanoscale ferromagnetic (FM) clusters driven by the reconfiguration of magnetic octupole symmetry and the displacement of Weyl nodes in momentum space, which act as topological interfacial pinning centers. This selectively enhances the in-plane (IP) EB field to 35.68 Oe while reducing the out-of-plane (OOP) component. The anisotropic EB can be independently controlled by adjusting the Mn3Ga thickness: the IP EB decreases with increasing thickness due to lattice relaxation, whereas the OOP EB increases, revealing distinct interfacial and bulk topological contributions related to the stabilization of the relaxed magnetic octupole state. The observed waist-shaped hysteresis loops indicate an asynchronous reversal mechanism governed by a graded pinning landscape originating from the interplay between lattice-induced DMI and Weyl node dynamics. These results establish that both the Ru seed layer and Mn3Ga thickness are effective tuning parameters for engineering room-temperature anisotropic EB effect, providing a promising route toward noncollinear antiferromagnetic MRAM and orientation-dependent spintronic devices.
{"title":"Engineering anisotropic room-temperature exchange bias in D019-Mn3Ga/CoFeB bilayer grown on Al2O3 substrates via Ru seed layer-induced interface modulation","authors":"Wei-Chih Chang","doi":"10.1016/j.vacuum.2026.115127","DOIUrl":"10.1016/j.vacuum.2026.115127","url":null,"abstract":"<div><div>Room-temperature exchange bias (EB) in Mn-based noncollinear antiferromagnets has drawn increasing attention for spintronic applications. However, in D0<sub>19</sub>-Mn<sub>3</sub>Ga/CoFeB system, the EB effect is usually restricted to low temperatures. Here, we demonstrate that introducing a Ru seed layer enables a tunable and anisotropic EB at room temperature. Interfacial strain induced by the Ru layer modulates the lattice symmetry and reconfigures the Dzyaloshinskii-Moriya interaction (DMI). These strain-mediated modifications promote the formation of nanoscale ferromagnetic (FM) clusters driven by the reconfiguration of magnetic octupole symmetry and the displacement of Weyl nodes in momentum space, which act as topological interfacial pinning centers. This selectively enhances the in-plane (IP) EB field to 35.68 Oe while reducing the out-of-plane (OOP) component. The anisotropic EB can be independently controlled by adjusting the Mn<sub>3</sub>Ga thickness: the IP EB decreases with increasing thickness due to lattice relaxation, whereas the OOP EB increases, revealing distinct interfacial and bulk topological contributions related to the stabilization of the relaxed magnetic octupole state. The observed waist-shaped hysteresis loops indicate an asynchronous reversal mechanism governed by a graded pinning landscape originating from the interplay between lattice-induced DMI and Weyl node dynamics. These results establish that both the Ru seed layer and Mn<sub>3</sub>Ga thickness are effective tuning parameters for engineering room-temperature anisotropic EB effect, providing a promising route toward noncollinear antiferromagnetic MRAM and orientation-dependent spintronic devices.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115127"},"PeriodicalIF":3.9,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1016/j.vacuum.2026.115129
Zhuofu Wei , Xiwen Hu , Shiyu Niu , Yuxin Wang , Zhongliang Liu , Zhenwen Yang , Ying Wang
To obtain the high-strength joint of zirconium alloy and stainless steel for nuclear applications, this study utilized a Ti interlayer for diffusion bonding of Zr-3 alloy and 304L stainless steel. Direct diffusion bonding resulted in the formation of numerous brittle intermetallic compounds, including Zr2(Fe, Ni) and Zr(Fe, Cr)2. The introduction of the Ti interlayer eliminated these phases, and the typical interfacial reaction layer of the joints was Zr-3/(Ti, Zr)/Ti/NiTi/TiFe/TiCr2/(Fe, Cr)/304L. The diffusion layer at the Ti/304L interface was identified as the key factor governing the joint's mechanical properties. Within this layer, TiFe and NiTi phases formed preferentially, followed by TiCr2 and (Fe, Cr) phases. Higher bonding temperatures and longer holding times significantly promoted the interdiffusion of Ti with Fe and Cr from the 304L steel. This enrichment of brittle TiFe and TiCr2 phases at the interface consequently degraded the joint properties. The joint achieved a peak shear strength of 247 MPa under the parameters of 760 °C/60 min/10 MPa, representing a 115 % increase compared to the direct diffusion-bonded joint. The fracture was primarily initiated in the brittle phases, such as TiFe and TiCr2, within the Ti/304L diffusion layer.
{"title":"Enhancement of interfacial structure and mechanical properties of Zr-3 alloy and 304L stainless steel diffusion bonded joint via Ti interlayer introduction","authors":"Zhuofu Wei , Xiwen Hu , Shiyu Niu , Yuxin Wang , Zhongliang Liu , Zhenwen Yang , Ying Wang","doi":"10.1016/j.vacuum.2026.115129","DOIUrl":"10.1016/j.vacuum.2026.115129","url":null,"abstract":"<div><div>To obtain the high-strength joint of zirconium alloy and stainless steel for nuclear applications, this study utilized a Ti interlayer for diffusion bonding of Zr-3 alloy and 304L stainless steel. Direct diffusion bonding resulted in the formation of numerous brittle intermetallic compounds, including Zr<sub>2</sub>(Fe, Ni) and Zr(Fe, Cr)<sub>2</sub>. The introduction of the Ti interlayer eliminated these phases, and the typical interfacial reaction layer of the joints was Zr-3/(Ti, Zr)/Ti/NiTi/TiFe/TiCr<sub>2</sub>/(Fe, Cr)/304L. The diffusion layer at the Ti/304L interface was identified as the key factor governing the joint's mechanical properties. Within this layer, TiFe and NiTi phases formed preferentially, followed by TiCr<sub>2</sub> and (Fe, Cr) phases. Higher bonding temperatures and longer holding times significantly promoted the interdiffusion of Ti with Fe and Cr from the 304L steel. This enrichment of brittle TiFe and TiCr<sub>2</sub> phases at the interface consequently degraded the joint properties. The joint achieved a peak shear strength of 247 MPa under the parameters of 760 °C/60 min/10 MPa, representing a 115 % increase compared to the direct diffusion-bonded joint. The fracture was primarily initiated in the brittle phases, such as TiFe and TiCr<sub>2</sub>, within the Ti/304L diffusion layer.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115129"},"PeriodicalIF":3.9,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1016/j.vacuum.2026.115124
S. Ghalab , Mansour Aouassa , A.K. Aladim , Saud A. Algarni , Majed Alharbi , Mohammed Ibrahim , K.M.A. Saron , Mohammed Bouabdellaoui , Isabelle Berbezier
In this work, we grow and investigate CMOS-compatible Ge quantum dots (Ge QDs) integrated into metal–oxide–semiconductor (MOS) photodetectors, with a focus on their electrical transport and photocurrent response. Crystalline Ge QDs with an average diameter of ≈5.8 nm, hemispherical shape, and a high density (∼5 × 1012 cm−2) are formed by solid-state dewetting of a 1 nm amorphous Ge film grown by molecular beam epitaxy (MBE) on SiO2/Si, subsequently capped with a 45 nm SiO2 layer, and finally converted into MOS Ge-QD photodetectors by depositing transparent AuPd pads. Temperature-dependent current–voltage and capacitance–voltage measurements, complemented by photocurrent analysis, reveal the formation of a Schottky-like MOS photodetector exhibiting a rectification ratio close to 102 and a low dark current. Charge transport is governed by thermionic emission assisted by Fowler–Nordheim tunneling, with the embedded Ge QDs acting as efficient charge-relay centers in the oxide, facilitating carrier injection and reducing the threshold voltage without degrading the capacitive behavior of the structure. Under illumination, the Ge-QD–based MOS photodetectors show a pronounced enhancement of photosensitivity, particularly in the visible spectral range, consistent with strong quantum confinement in the QDs. These results demonstrate that MBE-grown Ge QDs obtained by solid-state dewetting provide a promising platform for the realization of CMOS-compatible, low-power, high-performance optoelectronic devices, especially photodetectors and, more broadly, quantum-dot–engineered solar-cell architectures.
{"title":"CMOS-compatible MBE-grown germanium quantum dots for high-performance photodetectors and solar cells","authors":"S. Ghalab , Mansour Aouassa , A.K. Aladim , Saud A. Algarni , Majed Alharbi , Mohammed Ibrahim , K.M.A. Saron , Mohammed Bouabdellaoui , Isabelle Berbezier","doi":"10.1016/j.vacuum.2026.115124","DOIUrl":"10.1016/j.vacuum.2026.115124","url":null,"abstract":"<div><div>In this work, we grow and investigate CMOS-compatible Ge quantum dots (Ge QDs) integrated into metal–oxide–semiconductor (MOS) photodetectors, with a focus on their electrical transport and photocurrent response. Crystalline Ge QDs with an average diameter of ≈5.8 nm, hemispherical shape, and a high density (∼5 × 10<sup>12</sup> cm<sup>−2</sup>) are formed by solid-state dewetting of a 1 nm amorphous Ge film grown by molecular beam epitaxy (MBE) on SiO<sub>2</sub>/Si, subsequently capped with a 45 nm SiO<sub>2</sub> layer, and finally converted into MOS Ge-QD photodetectors by depositing transparent AuPd pads. Temperature-dependent current–voltage and capacitance–voltage measurements, complemented by photocurrent analysis, reveal the formation of a Schottky-like MOS photodetector exhibiting a rectification ratio close to 10<sup>2</sup> and a low dark current. Charge transport is governed by thermionic emission assisted by Fowler–Nordheim tunneling, with the embedded Ge QDs acting as efficient charge-relay centers in the oxide, facilitating carrier injection and reducing the threshold voltage without degrading the capacitive behavior of the structure. Under illumination, the Ge-QD–based MOS photodetectors show a pronounced enhancement of photosensitivity, particularly in the visible spectral range, consistent with strong quantum confinement in the QDs. These results demonstrate that MBE-grown Ge QDs obtained by solid-state dewetting provide a promising platform for the realization of CMOS-compatible, low-power, high-performance optoelectronic devices, especially photodetectors and, more broadly, quantum-dot–engineered solar-cell architectures.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115124"},"PeriodicalIF":3.9,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146025500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-20DOI: 10.1016/j.vacuum.2026.115125
Xiao Xi , Xuxu Liu , Wei Jin , Jipeng Zhu , Hai Jin , Xiaoqiu Ye , Changan Chen
In this study, a 13.56 MHz radio frequency power supply was used to generate an external solenoid inductively coupled plasma source. An ion energy mass spectrometer equipped with a Bessel box and quadrupole mass filter was employed to investigate the characteristics of ion in expansion region. The ion species, concentration and their energy distributions with different working gases, including deuterium, nitrogen and their mixtures, have been analyzed by adjusting the gas flow rate or relative concentration over a wide parametric range. The results give the evolution of deuterium series D+/D2+/D3+, nitrogen series N+/N2+/N2D+, and the ammonia series ND+/ND2+/ND3+/ND4+. The ion energy distribution of D3+, N2+ and ND4+ display multi-peak distributions, indicating sheath voltage modulation and frequent collisional production in gas phase. The signal intensities and peak energies of these ions show distinct trends with respect to the gas flow rate. The reaction processes been given to illustrate the transformation path within and between different ion series. The reactions can be divided into three stages: ionization regime, intermediate regime and recombination regime, depending on the overall gas flow rate. And the N2D+ is an effective media during molecular assisted recombination stage. These results benefit plasma processing and chemical synthesis.
{"title":"Distribution of ion energy and concentration in the expansion region of radio-frequency inductive coupled plasmas with deuterium and deuterium-nitrogen mixtures","authors":"Xiao Xi , Xuxu Liu , Wei Jin , Jipeng Zhu , Hai Jin , Xiaoqiu Ye , Changan Chen","doi":"10.1016/j.vacuum.2026.115125","DOIUrl":"10.1016/j.vacuum.2026.115125","url":null,"abstract":"<div><div>In this study, a 13.56 MHz radio frequency power supply was used to generate an external solenoid inductively coupled plasma source. An ion energy mass spectrometer equipped with a Bessel box and quadrupole mass filter was employed to investigate the characteristics of ion in expansion region. The ion species, concentration and their energy distributions with different working gases, including deuterium, nitrogen and their mixtures, have been analyzed by adjusting the gas flow rate or relative concentration over a wide parametric range. The results give the evolution of deuterium series D<sup>+</sup>/D<sub>2</sub><sup>+</sup>/D<sub>3</sub><sup>+</sup>, nitrogen series N<sup>+</sup>/N<sub>2</sub><sup>+</sup>/N<sub>2</sub>D<sup>+</sup>, and the ammonia series ND<sup>+</sup>/ND<sub>2</sub><sup>+</sup>/ND<sub>3</sub><sup>+</sup>/ND<sub>4</sub><sup>+</sup>. The ion energy distribution of D<sub>3</sub><sup>+</sup>, N<sub>2</sub><sup>+</sup> and ND<sub>4</sub><sup>+</sup> display multi-peak distributions, indicating sheath voltage modulation and frequent collisional production in gas phase. The signal intensities and peak energies of these ions show distinct trends with respect to the gas flow rate. The reaction processes been given to illustrate the transformation path within and between different ion series. The reactions can be divided into three stages: ionization regime, intermediate regime and recombination regime, depending on the overall gas flow rate. And the N<sub>2</sub>D<sup>+</sup> is an effective media during molecular assisted recombination stage. These results benefit plasma processing and chemical synthesis.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115125"},"PeriodicalIF":3.9,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146025511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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