Pub Date : 2024-11-02DOI: 10.1016/j.vacuum.2024.113769
Xiaolin Guo , Haiyu Li , Zhaoyang Zhang , Pengfei Xing , Shuai Wang , Shengnan Jiang , Yanxin Zhuang
A lightweight, heterogeneous, three-dimensional network-structured composite has been meticulously developed with the specific goal of optimizing impedance matching and elevating electromagnetic wave absorption properties. SiC nanowires-carbon composites were synthesized through a novel process involving combined carbothermal reduction and chemical vapor deposition, utilizing loofah sponge as the foundational material. Accessible and cost-effective organosilane waste was applied as the silicon source. The resulting composites manifest exceptional electromagnetic wave absorption performance with a minimum reflection loss of −46.34 dB and a wide effective bandwidth of 3.84 GHz at a thin thickness of 1.9 mm. Superior electromagnetic wave absorption is attributed to synergistic interplay of multiple interfacial polarizations, dipole polarization, conductive losses, and multiple reflections and scattering. This work presents an innovative pathway toward fabricating highly efficient electromagnetic wave-absorbing materials while effectively repurposing recycled waste.
{"title":"In situ formation SiC nanowires on loofah sponge-derived porous carbon for efficient electromagnetic wave absorption","authors":"Xiaolin Guo , Haiyu Li , Zhaoyang Zhang , Pengfei Xing , Shuai Wang , Shengnan Jiang , Yanxin Zhuang","doi":"10.1016/j.vacuum.2024.113769","DOIUrl":"10.1016/j.vacuum.2024.113769","url":null,"abstract":"<div><div>A lightweight, heterogeneous, three-dimensional network-structured composite has been meticulously developed with the specific goal of optimizing impedance matching and elevating electromagnetic wave absorption properties. SiC nanowires-carbon composites were synthesized through a novel process involving combined carbothermal reduction and chemical vapor deposition, utilizing loofah sponge as the foundational material. Accessible and cost-effective organosilane waste was applied as the silicon source. The resulting composites manifest exceptional electromagnetic wave absorption performance with a minimum reflection loss of −46.34 dB and a wide effective bandwidth of 3.84 GHz at a thin thickness of 1.9 mm. Superior electromagnetic wave absorption is attributed to synergistic interplay of multiple interfacial polarizations, dipole polarization, conductive losses, and multiple reflections and scattering. This work presents an innovative pathway toward fabricating highly efficient electromagnetic wave-absorbing materials while effectively repurposing recycled waste.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113769"},"PeriodicalIF":3.8,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657371","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 : 2024-11-01DOI: 10.1016/j.vacuum.2024.113792
Keke Huang , Yaotian Yan , Jingxuan Li , Liang Qiao , Jiehe Sui , Wei Cai , Xiaohang Zheng
Hard alloy type compounds are promising candidates for developing robust and cost-effective electrocatalysts due to the good conductivity and lattice hardness. However, their insufficient intrinsic activities require further surface modification, which remains a significant challenge due to the high hardness and surface inertness. Herein, a vacancies-promoted heteroatoms integration method is provided to construct Pt and Ni co-incorporated molybdenum carbide nanofibers ((Pt, Ni)-Mo2C). The Pt and Ni atoms filling into the Mo vacancy reduce the formation energy by ∼5.5 eV, which indicates an improved crystal stability. The electrons flow from Mo, Ni centers to Pt, C centers, resulting in the shifted average valence of Mo, Ni sites and moderate oxidation states of Pt, C sites. Therefore, the hydrogen adsorption free energy (ΔG∗H) of Mo and C sites increases from ∼-0.6 eV to ∼-0.03 eV (C sites) and ∼-0.2 eV (Mo sites), resulting in a state closer to ideal state (0 eV). As a result, the (Pt, Ni)-Mo2C catalyst exhibits an excellent overpotential of 64 mV at 10 mA cm−2 for hydrogen evolution reaction (HER), reducing by 149 mV than pure Mo2C. Current work paves a favorable method for integrating dissimilar atoms to modify hard alloy type compound surface.
硬质合金型化合物具有良好的导电性和晶格硬度，是开发坚固耐用且经济高效的电催化剂的理想候选材料。然而，由于硬度和表面惰性较高，它们的内在活性不足，需要进一步的表面改性，而这仍然是一个巨大的挑战。本文提供了一种空位促进杂原子整合的方法来构建铂和镍共嵌碳化钼纳米纤维（(Pt, Ni)-Mo2C）。填充到 Mo 空位中的铂原子和镍原子使形成能降低了 5.5 eV，从而提高了晶体的稳定性。电子从 Mo、Ni 中心流向 Pt、C 中心，导致 Mo、Ni 位点的平均价态偏移和 Pt、C 位点的中等氧化态。因此，Mo 和 C 位点的氢吸附自由能（ΔG∗H）从 ∼-0.6 eV 增加到 ∼-0.03 eV（C 位点）和 ∼-0.2 eV（Mo 位点），从而更接近理想状态（0 eV）。因此，(Pt, Ni)-Mo2C 催化剂在 10 mA cm-2 氢进化反应（HER）中表现出 64 mV 的优异过电位，比纯 Mo2C 减少了 149 mV。目前的工作为整合不同原子以改性硬质合金型化合物表面铺平了道路。
{"title":"Mo vacancies enhancing Pt, Ni co-incorporated Mo2C nanofibers for high-efficiency water decomposition","authors":"Keke Huang , Yaotian Yan , Jingxuan Li , Liang Qiao , Jiehe Sui , Wei Cai , Xiaohang Zheng","doi":"10.1016/j.vacuum.2024.113792","DOIUrl":"10.1016/j.vacuum.2024.113792","url":null,"abstract":"<div><div>Hard alloy type compounds are promising candidates for developing robust and cost-effective electrocatalysts due to the good conductivity and lattice hardness. However, their insufficient intrinsic activities require further surface modification, which remains a significant challenge due to the high hardness and surface inertness. Herein, a vacancies-promoted heteroatoms integration method is provided to construct Pt and Ni co-incorporated molybdenum carbide nanofibers ((Pt, Ni)-Mo<sub>2</sub>C). The Pt and Ni atoms filling into the Mo vacancy reduce the formation energy by ∼5.5 eV, which indicates an improved crystal stability. The electrons flow from Mo, Ni centers to Pt, C centers, resulting in the shifted average valence of Mo, Ni sites and moderate oxidation states of Pt, C sites. Therefore, the hydrogen adsorption free energy (ΔG<sub>∗H</sub>) of Mo and C sites increases from ∼-0.6 eV to ∼-0.03 eV (C sites) and ∼-0.2 eV (Mo sites), resulting in a state closer to ideal state (0 eV). As a result, the (Pt, Ni)-Mo<sub>2</sub>C catalyst exhibits an excellent overpotential of 64 mV at 10 mA cm<sup>−2</sup> for hydrogen evolution reaction (HER), reducing by 149 mV than pure Mo<sub>2</sub>C. Current work paves a favorable method for integrating dissimilar atoms to modify hard alloy type compound surface.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113792"},"PeriodicalIF":3.8,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659411","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 : 2024-11-01DOI: 10.1016/j.vacuum.2024.113795
Jia-Yu Bao , Si-Hai Wen , Yi Xiang , Le-Jun Wang , Tong-De Rao , Wen-Bo Yuan , Chun-Ming Yang , Mei-Ying Huang , Yong-Sheng Xie , Kai Wu , Lei Hu
Herein, we analyze the water decomposition possibility of single-layer (SL) GaInTe3 under the −2% to +2 % biaxial strain via first-principles stimulations. Our results find that SL GaInTe3 exhibits effective separation of photogenerated electrons and holes, which is strongly affirmed by the electronic property and the quite loose exciton binding. Furthermore, SL GaInTe3 has a suitable band edge and excellent visible-light capture ability, making it an ideal candidate for solar-assisted water decomposition. In addition, SL GaInTe3 shows a solar-to-hydrogen (STH) conversion of more than 33.0 %, further emphasizing its potential as a highly efficient photocatalyst. In conclusion, SL GaInTe3 has been supported by conclusive evidence as a photocatalytic material with excellent performance, providing new support and encouragement for the development of hydrogen production technology. Moreover, the effective thickness of 2D materials is defined as the largest spreading height of the electron cloud in covalent bonds perpendicular to the 2D atomic plane.
{"title":"Single-layer GaInTe3: Water-splitting photocatalyst low exciton binding and ultrahigh solar conversion efficiency","authors":"Jia-Yu Bao , Si-Hai Wen , Yi Xiang , Le-Jun Wang , Tong-De Rao , Wen-Bo Yuan , Chun-Ming Yang , Mei-Ying Huang , Yong-Sheng Xie , Kai Wu , Lei Hu","doi":"10.1016/j.vacuum.2024.113795","DOIUrl":"10.1016/j.vacuum.2024.113795","url":null,"abstract":"<div><div>Herein, we analyze the water decomposition possibility of single-layer (SL) GaInTe<sub>3</sub> under the −2% to +2 % biaxial strain via first-principles stimulations. Our results find that SL GaInTe<sub>3</sub> exhibits effective separation of photogenerated electrons and holes, which is strongly affirmed by the electronic property and the quite loose exciton binding. Furthermore, SL GaInTe<sub>3</sub> has a suitable band edge and excellent visible-light capture ability, making it an ideal candidate for solar-assisted water decomposition. In addition, SL GaInTe<sub>3</sub> shows a solar-to-hydrogen (STH) conversion of more than 33.0 %, further emphasizing its potential as a highly efficient photocatalyst. In conclusion, SL GaInTe<sub>3</sub> has been supported by conclusive evidence as a photocatalytic material with excellent performance, providing new support and encouragement for the development of hydrogen production technology. Moreover, the effective thickness of 2D materials is defined as the largest spreading height of the electron cloud in covalent bonds perpendicular to the 2D atomic plane.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113795"},"PeriodicalIF":3.8,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572293","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 : 2024-11-01DOI: 10.1016/j.vacuum.2024.113794
Amir Mohammad Ahadi , Tim Tjardts , Salih Veziroglu , Marie Elis , Thomas Strunskus , Lorenz Kienle , Franz Faupel , Alexander Vahl
Synthesis of multifunctional nanomaterials is known as a critical challenge in advanced nanoscience. Multicore@shell nanostructures are generated here via a gas phase synthesis approach. To achieve this objective, we used conventional DC magnetron sputtering in conjunction with a gas aggregation chamber. We employed a customized Au-Ti target to produce metal-metal oxide multicore@shell nanoparticles (NPs) with tunable properties. The deposited NPs were characterized with regard to their chemical composition, morphology, structural status, NP size distribution and optical properties. The obtained data clearly confirms that the crystalline Au cores are encapsulated in a TiOx matrix in each individual NP. Furthermore, the chemical composition and size distribution of the NPs can be affected by the operating pressure. Our approach provides a versatile route with many different possibilities to synthesize multicore@shell NPs from a variety of composite targets for well-desired applications including environmental, optical/plasmonic, and energy.
{"title":"Multicore@shell nanoparticle synthesis from a single multicomponent target by gas aggregation source","authors":"Amir Mohammad Ahadi , Tim Tjardts , Salih Veziroglu , Marie Elis , Thomas Strunskus , Lorenz Kienle , Franz Faupel , Alexander Vahl","doi":"10.1016/j.vacuum.2024.113794","DOIUrl":"10.1016/j.vacuum.2024.113794","url":null,"abstract":"<div><div>Synthesis of multifunctional nanomaterials is known as a critical challenge in advanced nanoscience. Multicore@shell nanostructures are generated here via a gas phase synthesis approach. To achieve this objective, we used conventional DC magnetron sputtering in conjunction with a gas aggregation chamber. We employed a customized Au-Ti target to produce metal-metal oxide multicore@shell nanoparticles (NPs) with tunable properties. The deposited NPs were characterized with regard to their chemical composition, morphology, structural status, NP size distribution and optical properties. The obtained data clearly confirms that the crystalline Au cores are encapsulated in a TiOx matrix in each individual NP. Furthermore, the chemical composition and size distribution of the NPs can be affected by the operating pressure. Our approach provides a versatile route with many different possibilities to synthesize multicore@shell NPs from a variety of composite targets for well-desired applications including environmental, optical/plasmonic, and energy.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113794"},"PeriodicalIF":3.8,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-31DOI: 10.1016/j.vacuum.2024.113791
Asma O. Al Ghaithi , Inas Taha , Sumayya M. Ansari , Nitul Rajput , Baker Mohammad , Haila M. Aldosari
This study examines the effects of annealing duration on the oxygen vacancies in gallium oxide (Ga2O3) thin films. Ga2O3 thin films were deposited by RF magnetron sputtering on (100) silicon substrates and subsequently annealed in an argon atmosphere at 1000 °C for 1, 2, 4, and 7 h. The impact of the annealing time on the morphology, oxygen content, optical bandgap, and thickness of Ga2O3 thin films was thoroughly investigated. All annealed films exhibited a polycrystalline β-Ga2O3 phase with a monoclinic crystal structure and a preferred orientation along the (400) plane. Increasing the annealing time resulted in larger grains, a denser interfacial layer, and reduced microstrain. Prolonged annealing also facilitated the escape of oxygen atoms, creating oxygen vacancies that formed a defect band below the conduction band, significantly lowering the optical bandgap. Cross-sectional transmission electron microscopy revealed a Ga2O3/SiO2 heterostructure formation, with Ga2O3 thickness decreasing and SiO2 thickness increasing with longer annealing times. These findings enhance the understanding of the role of annealing in optimizing Ga2O3 thin films for electronic and optoelectronic applications.
{"title":"Tailoring oxygen vacancies in Ga2O3 thin films and controlled formation of Ga2O3/SiO2 heterostructures via annealing","authors":"Asma O. Al Ghaithi , Inas Taha , Sumayya M. Ansari , Nitul Rajput , Baker Mohammad , Haila M. Aldosari","doi":"10.1016/j.vacuum.2024.113791","DOIUrl":"10.1016/j.vacuum.2024.113791","url":null,"abstract":"<div><div>This study examines the effects of annealing duration on the oxygen vacancies in gallium oxide (Ga<sub>2</sub>O<sub>3</sub>) thin films. Ga<sub>2</sub>O<sub>3</sub> thin films were deposited by RF magnetron sputtering on (100) silicon substrates and subsequently annealed in an argon atmosphere at 1000 °C for 1, 2, 4, and 7 h. The impact of the annealing time on the morphology, oxygen content, optical bandgap, and thickness of Ga<sub>2</sub>O<sub>3</sub> thin films was thoroughly investigated. All annealed films exhibited a polycrystalline β-Ga<sub>2</sub>O<sub>3</sub> phase with a monoclinic crystal structure and a preferred orientation along the (400) plane. Increasing the annealing time resulted in larger grains, a denser interfacial layer, and reduced microstrain. Prolonged annealing also facilitated the escape of oxygen atoms, creating oxygen vacancies that formed a defect band below the conduction band, significantly lowering the optical bandgap. Cross-sectional transmission electron microscopy revealed a Ga<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> heterostructure formation, with Ga<sub>2</sub>O<sub>3</sub> thickness decreasing and SiO<sub>2</sub> thickness increasing with longer annealing times. These findings enhance the understanding of the role of annealing in optimizing Ga<sub>2</sub>O<sub>3</sub> thin films for electronic and optoelectronic applications.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113791"},"PeriodicalIF":3.8,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572212","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 : 2024-10-30DOI: 10.1016/j.vacuum.2024.113790
Kaikai Xu , Yadong Gong , Jibin Zhao , Qiang Zhao
This paper presents the establishment of a melt pool flow model, wherein the solute field and phase field are concurrently integrated to simulate the dynamic transformations within the melt pool and the evolution of dendrites during the solidification process. Experimental validation affirms the model's precision. The simulation outcomes indicate the persistence of a pronounced symmetry within the melt pool throughout the flow process. Intriguingly, perturbations in the powder and variations in heat transfer give rise to a vortex-like internal flow pattern within the melt pool. These findings align harmoniously with the experimental results concerning the dimensions of the melt pool (melt width, melt depth, and melt height). Specifically, the growth rate of dendrite tips and the dendrite count exhibit significant sensitivity to alterations in temperature gradient. As the temperature gradient escalates, the primary dendrite arm spacing diminishes, accompanied by heightened development of secondary dendrite arms. In congruence with the simulated dendrite evolution process, the microstructure within the deposited layer derived from experimental observations primarily comprises columnar crystals. The growth of dendrites unfolds perpendicularly to the melt pool boundary, following the trajectory of decreasing temperature gradient, thereby mirroring the simulated dendrite evolution process.
{"title":"Microscopic scale analysis of the dynamic changes of the melt pool and the evolution of dendritic structure during L-DED of GH3536 alloy","authors":"Kaikai Xu , Yadong Gong , Jibin Zhao , Qiang Zhao","doi":"10.1016/j.vacuum.2024.113790","DOIUrl":"10.1016/j.vacuum.2024.113790","url":null,"abstract":"<div><div>This paper presents the establishment of a melt pool flow model, wherein the solute field and phase field are concurrently integrated to simulate the dynamic transformations within the melt pool and the evolution of dendrites during the solidification process. Experimental validation affirms the model's precision. The simulation outcomes indicate the persistence of a pronounced symmetry within the melt pool throughout the flow process. Intriguingly, perturbations in the powder and variations in heat transfer give rise to a vortex-like internal flow pattern within the melt pool. These findings align harmoniously with the experimental results concerning the dimensions of the melt pool (melt width, melt depth, and melt height). Specifically, the growth rate of dendrite tips and the dendrite count exhibit significant sensitivity to alterations in temperature gradient. As the temperature gradient escalates, the primary dendrite arm spacing diminishes, accompanied by heightened development of secondary dendrite arms. In congruence with the simulated dendrite evolution process, the microstructure within the deposited layer derived from experimental observations primarily comprises columnar crystals. The growth of dendrites unfolds perpendicularly to the melt pool boundary, following the trajectory of decreasing temperature gradient, thereby mirroring the simulated dendrite evolution process.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113790"},"PeriodicalIF":3.8,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572214","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 : 2024-10-29DOI: 10.1016/j.vacuum.2024.113780
D. Surya Reddy , V. Rajagopal Reddy , V. Janardhanam , Chel-Jong Choi
To comprehend the effect of the e-beam deposited high-k holmium oxide (Ho2O3) on the electrical possessions of Au/n-GaN/Ti/Al Schottky contact (SC), Au/Ho2O3/n-GaN/Ti/Al MIS-type contact was created with a Ho2O3 interlayer. The microstructural and chemical possessions of Ho2O3 film were assessed using XRD, XPS, TEM and EDX approaches. XRD, XPS, TEM and EDX studies indicate that the Ho2O3 layer exists on the GaN. The electrical features of the SC and MIS contact were probed using I-V and C-V approaches. The MIS contact shows a notable rectifying manner with a lower reverse leakage current than the SC. The MIS contact exhibits superior Φb (0.85 eV) than the SC (0.72 eV), indicating the Ho2O3 interlayer greatly rehabilitated the Φb of the SC. Using I-V, C-V, Cheung's and Norde processes, Φb, n, and RS of the SC and MIS contacts were estimated, and the estimated Φb were well matched with each other, which signifying the techniques used here steadiness and validity. The MIS contact exhibits a lower magnitude of NSS compared to the SC, portentous that the presence of the Ho2O3 layer played a significant part in diminishing NSS. The log (I) versus log (V) of forward bias of the SC and MIS contact reveals the ohmic nature and space charge limited current (SCLC) at the lower bias and upper bias sections. The conclusions suggest that the Ho2O3 material has potential for building MIS/MOS devices.
{"title":"Microstructural and chemical properties of high-k holmium oxide (Ho2O3) and its effect on interface properties and current transport process of Au/n-GaN/Ti/Al Schottky contact as an interlayer","authors":"D. Surya Reddy , V. Rajagopal Reddy , V. Janardhanam , Chel-Jong Choi","doi":"10.1016/j.vacuum.2024.113780","DOIUrl":"10.1016/j.vacuum.2024.113780","url":null,"abstract":"<div><div>To comprehend the effect of the e-beam deposited high-k holmium oxide (Ho<sub>2</sub>O<sub>3</sub>) on the electrical possessions of Au/n-GaN/Ti/Al Schottky contact (SC), Au/Ho<sub>2</sub>O<sub>3</sub>/n-GaN/Ti/Al MIS-type contact was created with a Ho<sub>2</sub>O<sub>3</sub> interlayer. The microstructural and chemical possessions of Ho<sub>2</sub>O<sub>3</sub> film were assessed using XRD, XPS, TEM and EDX approaches. XRD, XPS, TEM and EDX studies indicate that the Ho<sub>2</sub>O<sub>3</sub> layer exists on the GaN. The electrical features of the SC and MIS contact were probed using I-V and C-V approaches. The MIS contact shows a notable rectifying manner with a lower reverse leakage current than the SC. The MIS contact exhibits superior Φ<sub>b</sub> (0.85 eV) than the SC (0.72 eV), indicating the Ho<sub>2</sub>O<sub>3</sub> interlayer greatly rehabilitated the Φ<sub>b</sub> of the SC. Using I-V, C-V, Cheung's and Norde processes, Φ<sub>b</sub>, n, and R<sub>S</sub> of the SC and MIS contacts were estimated, and the estimated Φ<sub>b</sub> were well matched with each other, which signifying the techniques used here steadiness and validity. The MIS contact exhibits a lower magnitude of N<sub>SS</sub> compared to the SC, portentous that the presence of the Ho<sub>2</sub>O<sub>3</sub> layer played a significant part in diminishing N<sub>SS</sub>. The log (I) versus log (V) of forward bias of the SC and MIS contact reveals the ohmic nature and space charge limited current (SCLC) at the lower bias and upper bias sections. The conclusions suggest that the Ho<sub>2</sub>O<sub>3</sub> material has potential for building MIS/MOS devices.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113780"},"PeriodicalIF":3.8,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572213","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 : 2024-10-28DOI: 10.1016/j.vacuum.2024.113776
Yanping Lv, Zhuanzhuan Song, Ziyi Qin, Jun Zhang, Ming Yang, Hao Wu
Tin sulfide (SnS) is a highly promising photovoltaic absorption material in thin-film solar cells with abundant reserves, environmental friendliness, low cost and long-term stability. An efficiency of up to 4.8 % has been achieved for SnS absorber/CdS heterojunction solar cells where the CdS buffer layer is usually obtained by chemical bath deposition. However, current CdS/SnS devices often suffer from severe interface recombination loss, which deteriorates device performance. This report focuses on the CdS film surface to identify performance-degrading factors for CdS/SnS-based solar cells. XRD and XPS reveal numerous oxides on freshly fabricated CdS films increasing surface roughness and reducing conductivity. Herein, a method based on ammonium sulfide (AS) chemical treatment is proposed, which can effectively reduce the oxide content on the surface of CdS and optimize the band alignment, leading to the facilitation of charge carrier transport and the suppression of interface recombination. Consequently, the PCE of the FTO/CdS/SnS/Ag device is enhanced about three times (from 0.18 % to 0.47 %) with excellent moisture stability.
{"title":"Probing into the low efficiency of CdS/SnS-based solar cells and remediation through surface treatments","authors":"Yanping Lv, Zhuanzhuan Song, Ziyi Qin, Jun Zhang, Ming Yang, Hao Wu","doi":"10.1016/j.vacuum.2024.113776","DOIUrl":"10.1016/j.vacuum.2024.113776","url":null,"abstract":"<div><div>Tin sulfide (SnS) is a highly promising photovoltaic absorption material in thin-film solar cells with abundant reserves, environmental friendliness, low cost and long-term stability. An efficiency of up to 4.8 % has been achieved for SnS absorber/CdS heterojunction solar cells where the CdS buffer layer is usually obtained by chemical bath deposition. However, current CdS/SnS devices often suffer from severe interface recombination loss, which deteriorates device performance. This report focuses on the CdS film surface to identify performance-degrading factors for CdS/SnS-based solar cells. XRD and XPS reveal numerous oxides on freshly fabricated CdS films increasing surface roughness and reducing conductivity. Herein, a method based on ammonium sulfide (AS) chemical treatment is proposed, which can effectively reduce the oxide content on the surface of CdS and optimize the band alignment, leading to the facilitation of charge carrier transport and the suppression of interface recombination. Consequently, the PCE of the FTO/CdS/SnS/Ag device is enhanced about three times (from 0.18 % to 0.47 %) with excellent moisture stability.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113776"},"PeriodicalIF":3.8,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142560730","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 : 2024-10-28DOI: 10.1016/j.vacuum.2024.113778
Kejing Liu , Wanqi Jie , Zhe Kang , Jinbo Liu , Xianggang Zhang , Shixuan Guo , Zhuochen Cai , Dan Zheng , Ziang Yin , Qinghua Zhao , Fa Luo , Shitao Xiong , Shusheng Wang , Xuxin He , Aizhong Yue , Tao Wang
Both radioactive isotopes 138La and 227Ac in LaBr3:Ce crystal typically produce considerable intrinsic background signals, and thus hinder their applications with low count rates. Since the complete separation of 138La is almost impossible, the contamination of 138La is stubbornly present in all La-halide based scintillators. In this study, an efficient purification protocol based on vacuum distillation was developed to separate 227Ac from feedstock and reduce intrinsic background signal at 1.6–3 MeV introduced by 227Ac in LaBr3:Ce crystals. Through combined theoretical and experimental analysis, the alpha contamination from 227Ac in LaBr3: Ce was reduced exploiting the different evaporation behaviors of LaBr3 and AcBr3. Additional impurities were also reduced to lower levels, as confirmed by glow discharge mass spectrometry (GDMS). The purified material, distilled at various temperatures (1203 K, 1253 K, and 1303 K), was used to grow LaBr3:Ce single crystals for performance evaluation. The crystals distilled at 1203 K demonstrated enhanced scintillation performance, featuring lower background counts (0.0181 counts·s−1·cm−3 @1.6–3 MeV) by approximately 50%–60 % of untreated sample and excellent energy resolution (2.47 %@662 KeV). This study presents an effective approach for preparing low-background lanthanum bromide, so as to offer valuable insights for isotope separation in scintillation crystals by vacuum distillation.
{"title":"Separation of radioactive isotope 227Ac from LaBr3 via vacuum evaporation for low-background scintillating detectors","authors":"Kejing Liu , Wanqi Jie , Zhe Kang , Jinbo Liu , Xianggang Zhang , Shixuan Guo , Zhuochen Cai , Dan Zheng , Ziang Yin , Qinghua Zhao , Fa Luo , Shitao Xiong , Shusheng Wang , Xuxin He , Aizhong Yue , Tao Wang","doi":"10.1016/j.vacuum.2024.113778","DOIUrl":"10.1016/j.vacuum.2024.113778","url":null,"abstract":"<div><div>Both radioactive isotopes <sup>138</sup>La and <sup>227</sup>Ac in LaBr<sub>3</sub>:Ce crystal typically produce considerable intrinsic background signals, and thus hinder their applications with low count rates. Since the complete separation of <sup>138</sup>La is almost impossible, the contamination of <sup>138</sup>La is stubbornly present in all La-halide based scintillators. In this study, an efficient purification protocol based on vacuum distillation was developed to separate <sup>227</sup>Ac from feedstock and reduce intrinsic background signal at 1.6–3 MeV introduced by <sup>227</sup>Ac in LaBr<sub>3</sub>:Ce crystals. Through combined theoretical and experimental analysis, the alpha contamination from <sup>227</sup>Ac in LaBr<sub>3</sub>: Ce was reduced exploiting the different evaporation behaviors of LaBr<sub>3</sub> and AcBr<sub>3</sub>. Additional impurities were also reduced to lower levels, as confirmed by glow discharge mass spectrometry (GDMS). The purified material, distilled at various temperatures (1203 K, 1253 K, and 1303 K), was used to grow LaBr<sub>3</sub>:Ce single crystals for performance evaluation. The crystals distilled at 1203 K demonstrated enhanced scintillation performance, featuring lower background counts (0.0181 counts·s<sup>−1</sup>·cm<sup>−3</sup> @1.6–3 MeV) by approximately 50%–60 % of untreated sample and excellent energy resolution (2.47 %@662 KeV). This study presents an effective approach for preparing low-background lanthanum bromide, so as to offer valuable insights for isotope separation in scintillation crystals by vacuum distillation.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113778"},"PeriodicalIF":3.8,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538178","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}
A vacuum system is one of the crucial components of the Electron Beam-Powder Bed Fusion Process (EB-PBF). It ensures the generation of a high-intensity electron beam. This paper presents a vacuum system design for the EB-PBF process. The work chamber and EB gun chamber have been designed and verified using ANSYS workbench for stress, strain, and deformation limits and found satisfactory. The analytical calculations have been performed for all the pumps, considering the various gas loads during the process. After the design, the vacuum system has been fabricated and tested for its stability, ultimate vacuum, and leak rate. The helium leak test results show that all the joints have a leak rate better than 1 × 10−8 mbar l/s. Further, the analytical results of each pump have been compared with experimental results and found almost in line with the theoretical results. The results show that a pressure lower than 1 × 10−5 mbar and 5 × 10−6 mbar can be achieved in the work chamber and EB gun chamber in less than 23 min and 10 min respectively. The chamber was evacuated multiple times and found that the chamber could still hold pressure better than 1 × 10−2 mbar after 48 h.
{"title":"Design and development of vacuum system for electron beam powder bed fusion process","authors":"Avinash Kumar Mehta , Gopal Gote , Kalpit Solanki , Yogesh Patil , Yash Mittal , V.N. Ramani , K.P. Karunakaran","doi":"10.1016/j.vacuum.2024.113779","DOIUrl":"10.1016/j.vacuum.2024.113779","url":null,"abstract":"<div><div>A vacuum system is one of the crucial components of the Electron Beam-Powder Bed Fusion Process (EB-PBF). It ensures the generation of a high-intensity electron beam. This paper presents a vacuum system design for the EB-PBF process. The work chamber and EB gun chamber have been designed and verified using ANSYS workbench for stress, strain, and deformation limits and found satisfactory. The analytical calculations have been performed for all the pumps, considering the various gas loads during the process. After the design, the vacuum system has been fabricated and tested for its stability, ultimate vacuum, and leak rate. The helium leak test results show that all the joints have a leak rate better than 1 × 10<sup>−8</sup> mbar l/s. Further, the analytical results of each pump have been compared with experimental results and found almost in line with the theoretical results. The results show that a pressure lower than 1 × 10<sup>−5</sup> mbar and 5 × 10<sup>−6</sup> mbar can be achieved in the work chamber and EB gun chamber in less than 23 min and 10 min respectively. The chamber was evacuated multiple times and found that the chamber could still hold pressure better than 1 × 10<sup>−2</sup> mbar after 48 h.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113779"},"PeriodicalIF":3.8,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142577868","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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