Experiments on field electron emission from single-tip nanoemitters have typically been carried out using a counter-electrode with a finite curvature radius R, positioned at a distance dgap from the emitter's apex. The effects of the counter-electrode's curvature on the apex field enhancement factor (γCa) of the emitter are still not understood. In this Letter, we theoretically explore how the apex field enhancement factor of an emitter, represented by a hemisphere on a cylindrical post (HCP) with apex radius ra=50 nm, is influenced by the curvature of a sphere-shaped counter-electrode. Importantly, our results show that for HCPs with sharpness aspect ratios typically between 102 and 103, there is a universal scaling such that γCa=γPaΨ(R/dgap), where γPa represents the apex field enhancement factor for the emitter assuming a planar counter-electrode, and Ψ(R/dgap) is a universal scaling function such that Ψ∼1 for R/dgap≫1 and Ψ∼(R/dgap)α, with α close to unity, for R/dgap≪1. These findings help partially explain discrepancies observed in orthodox field electron emission experiments, where it was reported that the effective γCa values extracted from the current–voltage characteristics of single-tip carbon nanotubes typically underestimate the theoretical γPa values when R∼dgap≫ra, a trend that is predicted by our results.
{"title":"Universal scaling of electrostatic effects of a curved counter-electrode on the emitter field enhancement","authors":"Thiago A. de Assis, Fernando F. Dall'Agnol","doi":"10.1063/5.0252449","DOIUrl":"https://doi.org/10.1063/5.0252449","url":null,"abstract":"Experiments on field electron emission from single-tip nanoemitters have typically been carried out using a counter-electrode with a finite curvature radius R, positioned at a distance dgap from the emitter's apex. The effects of the counter-electrode's curvature on the apex field enhancement factor (γCa) of the emitter are still not understood. In this Letter, we theoretically explore how the apex field enhancement factor of an emitter, represented by a hemisphere on a cylindrical post (HCP) with apex radius ra=50 nm, is influenced by the curvature of a sphere-shaped counter-electrode. Importantly, our results show that for HCPs with sharpness aspect ratios typically between 102 and 103, there is a universal scaling such that γCa=γPaΨ(R/dgap), where γPa represents the apex field enhancement factor for the emitter assuming a planar counter-electrode, and Ψ(R/dgap) is a universal scaling function such that Ψ∼1 for R/dgap≫1 and Ψ∼(R/dgap)α, with α close to unity, for R/dgap≪1. These findings help partially explain discrepancies observed in orthodox field electron emission experiments, where it was reported that the effective γCa values extracted from the current–voltage characteristics of single-tip carbon nanotubes typically underestimate the theoretical γPa values when R∼dgap≫ra, a trend that is predicted by our results.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"57 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143393691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rare-earth oxides (REOs) represented by CeO2 and La2O3 became a focal point in the study of Li-ion battery (LIB) electrode materials. However, leveraging defects to tune the intrinsic electronic structure of REO to enhance electrochemical performance, as well as understanding the underlying physical mechanisms at the atomic level, remained an open challenge. Density functional theory plus U calculations revealed that doping and oxygen vacancies not only regulated Li-ion insertion stability but also reduced the migration energy barriers in CeO2. Doping also decreased the volume change rate of CeO2 during Li-ion insertion. Oxygen vacancies lowered the Li-ion migration energy barrier in CeO2 from 1.516 to 0.903 eV. In comparison, Li-ion migration energy barriers in the La2O3 series structures were significantly lower than those in CeO2. Experimental results confirmed that the Li-ion diffusion coefficient of La2O3 was markedly higher than that of CeO2. Upon Li-ion insertion, the bandgap of CeO2 decreased from 2.18 to 1.60 eV, and density of states analysis revealed the profound impact of lithiation on the electronic structure. This comprehensive study enhances the understanding of the application potential of these typical rare-earth oxide materials in LIBs.
{"title":"Li-ion storage characteristics and migration mechanisms of intrinsic, doped, and oxygen-deficient CeO2 and La2O3: A study using DFT+U","authors":"Yucheng Hu, Na Jin, Lei Sun, Ying Liu, Xin Tian","doi":"10.1063/5.0251743","DOIUrl":"https://doi.org/10.1063/5.0251743","url":null,"abstract":"Rare-earth oxides (REOs) represented by CeO2 and La2O3 became a focal point in the study of Li-ion battery (LIB) electrode materials. However, leveraging defects to tune the intrinsic electronic structure of REO to enhance electrochemical performance, as well as understanding the underlying physical mechanisms at the atomic level, remained an open challenge. Density functional theory plus U calculations revealed that doping and oxygen vacancies not only regulated Li-ion insertion stability but also reduced the migration energy barriers in CeO2. Doping also decreased the volume change rate of CeO2 during Li-ion insertion. Oxygen vacancies lowered the Li-ion migration energy barrier in CeO2 from 1.516 to 0.903 eV. In comparison, Li-ion migration energy barriers in the La2O3 series structures were significantly lower than those in CeO2. Experimental results confirmed that the Li-ion diffusion coefficient of La2O3 was markedly higher than that of CeO2. Upon Li-ion insertion, the bandgap of CeO2 decreased from 2.18 to 1.60 eV, and density of states analysis revealed the profound impact of lithiation on the electronic structure. This comprehensive study enhances the understanding of the application potential of these typical rare-earth oxide materials in LIBs.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"162 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ronggui Zhu, Tong Guo, Lei Ding, Fei Meng, Boyi Wang, Yu Qi, Xutong Meng, Baohe Li, Chun Feng, Guanghua Yu
The construction of irradiation-tolerant anisotropic magnetoresistance (AMR) sensors is crucial for weak-field detection in scenarios of aerospace and radiotherapy. Presently, the utilization of the NiFe/oxide composite structure was considered to be an effective scheme to optimize the spin-dependent transport property; however, it exhibited poor anti-irradiation ability due to the crystal instability of oxide. Here, a strategy was proposed to break through the limitation based on the electronic reconstruction and structural stabilization. By introducing an oxygen-affinitive Hf intercalation into the Ta/MgO/NiFe/MgO/Ta multilayer, the electron coordination was modified to tune the 3d orbital occupancy of Fe, apparently boosting the s-d electron scattering and spin-related transport property. Meanwhile, the irradiation stability of electronic and crystal structures was effectively improved due to the emergence of the Hf–O–Mg bond with high dissociation energy. Therefore, we constructed a highly reliable AMR sensor with both the ultrahigh sensitivity of 3.1 mV/V/Oe and excellent irradiation-tolerant ability capable of resisting the γ-ray irradiation of 1000 Gy. These results not only build an important basis for the sensor application in the irradiation environment but also provide a possible idea for the anti-irradiation design in spintronic devices.
{"title":"Anti-irradiation reinforcement in NiFe/oxide composite structure by electronic reconstruction and structural stabilization for efficient magnetoresistive sensor in aerospace/radiotherapy applications","authors":"Ronggui Zhu, Tong Guo, Lei Ding, Fei Meng, Boyi Wang, Yu Qi, Xutong Meng, Baohe Li, Chun Feng, Guanghua Yu","doi":"10.1063/5.0251492","DOIUrl":"https://doi.org/10.1063/5.0251492","url":null,"abstract":"The construction of irradiation-tolerant anisotropic magnetoresistance (AMR) sensors is crucial for weak-field detection in scenarios of aerospace and radiotherapy. Presently, the utilization of the NiFe/oxide composite structure was considered to be an effective scheme to optimize the spin-dependent transport property; however, it exhibited poor anti-irradiation ability due to the crystal instability of oxide. Here, a strategy was proposed to break through the limitation based on the electronic reconstruction and structural stabilization. By introducing an oxygen-affinitive Hf intercalation into the Ta/MgO/NiFe/MgO/Ta multilayer, the electron coordination was modified to tune the 3d orbital occupancy of Fe, apparently boosting the s-d electron scattering and spin-related transport property. Meanwhile, the irradiation stability of electronic and crystal structures was effectively improved due to the emergence of the Hf–O–Mg bond with high dissociation energy. Therefore, we constructed a highly reliable AMR sensor with both the ultrahigh sensitivity of 3.1 mV/V/Oe and excellent irradiation-tolerant ability capable of resisting the γ-ray irradiation of 1000 Gy. These results not only build an important basis for the sensor application in the irradiation environment but also provide a possible idea for the anti-irradiation design in spintronic devices.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"6 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143393695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yinxuan Zhu, Andrew A. Allerman, Chandan Joishi, Jonathan Pratt, Agnes Maneesha Dominic Merwin Xavier, Gabriel Calderon Ortiz, Brianna A. Klein, Andrew Armstrong, Jinwoo Hwang, Siddharth Rajan
We report on the heterostructure and interfacial engineering of metalorganic chemical vapor deposition (MOCVD) grown reverse graded contacts to ultra-wide bandgap AlGaN. A record low contact resistivity of 1.4 × 10−6 Ω cm2 was reported on an Al0.82Ga0.18N metal-semiconductor field effect transistor by compositionally grading the contact layer from Al0.85Ga0.15N → Al0.14Ga0.86N with degenerate doping and proper interfacial engineering considering bandgap-narrowing-induced band offset between the channel and the contact layer. This represents orders-of-magnitude of lower contact resistivity than that obtained in similar MOCVD-grown structures. A detailed, layer-by-layer analysis of the reverse graded contact and TCAD simulation of the bandgap narrowing effect highlighted that the reverse graded contact layer itself is extremely conductive, and interfacial resistance due to bandgap-narrowing-induced barrier between contact and channel dominates the contact resistance.
{"title":"Heterostructure and interfacial engineering for low-resistance contacts to ultra-wide bandgap AlGaN","authors":"Yinxuan Zhu, Andrew A. Allerman, Chandan Joishi, Jonathan Pratt, Agnes Maneesha Dominic Merwin Xavier, Gabriel Calderon Ortiz, Brianna A. Klein, Andrew Armstrong, Jinwoo Hwang, Siddharth Rajan","doi":"10.1063/5.0230220","DOIUrl":"https://doi.org/10.1063/5.0230220","url":null,"abstract":"We report on the heterostructure and interfacial engineering of metalorganic chemical vapor deposition (MOCVD) grown reverse graded contacts to ultra-wide bandgap AlGaN. A record low contact resistivity of 1.4 × 10−6 Ω cm2 was reported on an Al0.82Ga0.18N metal-semiconductor field effect transistor by compositionally grading the contact layer from Al0.85Ga0.15N → Al0.14Ga0.86N with degenerate doping and proper interfacial engineering considering bandgap-narrowing-induced band offset between the channel and the contact layer. This represents orders-of-magnitude of lower contact resistivity than that obtained in similar MOCVD-grown structures. A detailed, layer-by-layer analysis of the reverse graded contact and TCAD simulation of the bandgap narrowing effect highlighted that the reverse graded contact layer itself is extremely conductive, and interfacial resistance due to bandgap-narrowing-induced barrier between contact and channel dominates the contact resistance.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"22 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143393693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yu-Cheng Li, Che-Hao Chang, Yu-Jui Wu, Chen-Yao Liao, Jiun-Yun Li
Si-based spin qubits are promising due to their long decoherence time and the compatibility with state-of-the-art semiconductor technology and have been demonstrated using quantum dots (QDs) to host single electrons for spin manipulation. In this work, we simulate the electrostatics and quantum transport properties of quantum dots on a Si metal–oxide–semiconductor platform and a Si/SiGe heterostructure. We investigate the effects of gate configurations and the SiGe spacer thickness on device characteristics, such as gate capacitances, Coulomb blockade, and charge stability. For a single quantum dot, placing its barrier gates (BGs) under the plunger gate improves the charge stability, while swapping the positions of those gates reduces the effects of the barrier gate biases on the charge stability. A thicker SiGe spacer further suppresses the effects of the barrier gate biases on the charge stability for quantum dots on the Si/SiGe heterostructure but leads to stronger crosstalk between neighboring quantum dots. Wider barrier gates can help to mitigate the crosstalk effects for multiple quantum dots. These findings provide key insights into the optimization of the gate configurations and material selection to improve the charge stability and minimize the crosstalk by different gates for future development of scalable Si-based quantum dots.
{"title":"Design guidelines for Si metal–oxide–semiconductor and Si/SiGe heterostructure quantum dots for spin qubits","authors":"Yu-Cheng Li, Che-Hao Chang, Yu-Jui Wu, Chen-Yao Liao, Jiun-Yun Li","doi":"10.1063/5.0245929","DOIUrl":"https://doi.org/10.1063/5.0245929","url":null,"abstract":"Si-based spin qubits are promising due to their long decoherence time and the compatibility with state-of-the-art semiconductor technology and have been demonstrated using quantum dots (QDs) to host single electrons for spin manipulation. In this work, we simulate the electrostatics and quantum transport properties of quantum dots on a Si metal–oxide–semiconductor platform and a Si/SiGe heterostructure. We investigate the effects of gate configurations and the SiGe spacer thickness on device characteristics, such as gate capacitances, Coulomb blockade, and charge stability. For a single quantum dot, placing its barrier gates (BGs) under the plunger gate improves the charge stability, while swapping the positions of those gates reduces the effects of the barrier gate biases on the charge stability. A thicker SiGe spacer further suppresses the effects of the barrier gate biases on the charge stability for quantum dots on the Si/SiGe heterostructure but leads to stronger crosstalk between neighboring quantum dots. Wider barrier gates can help to mitigate the crosstalk effects for multiple quantum dots. These findings provide key insights into the optimization of the gate configurations and material selection to improve the charge stability and minimize the crosstalk by different gates for future development of scalable Si-based quantum dots.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"55 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yi-Zhe Huang, Qiang Yang, Han Xiong, Huai-Qing Zhang
This paper presents a polarization-insensitive microwave power receiving composite metasurface array. The composite array consists of a reflection phase gradient metasurface array and a horizontal omnidirectional antenna, with a central operating frequency of 5.8 GHz. The reflection phase gradient metasurface array elements are insensitive to the polarization of the incident wave and are arranged radially around the array center. This configuration creates a radial reflection phase gradient that efficiently converts incident plane waves of different polarizations into surface waves converging toward the center. The surface wave energy is then extracted by the horizontal omnidirectional antenna and converted into direct current (DC) by a rectifier. Numerical simulations demonstrate that the composite array maintains effective surface wave excitation and propagation toward the center for both circularly polarized and various horizontally polarized plane waves, achieving a plane wave-to-surface wave conversion efficiency of 74.89%. Experimental validation shows that the proposed array achieves a maximum energy collection efficiency of 62.23% and an RF-DC conversion efficiency of 39.96% over a broad frequency range of 5.6–6.0 GHz. This study achieves polarization insensitivity while simultaneously enhancing the operational efficiency of microwave energy receivers. The results offer a valuable design reference for leveraging reflection phase gradient arrays in wireless power transfer applications.
{"title":"Polarization-insensitive microwave power receiving composite array based on reflection phase gradient metasurfaces","authors":"Yi-Zhe Huang, Qiang Yang, Han Xiong, Huai-Qing Zhang","doi":"10.1063/5.0248205","DOIUrl":"https://doi.org/10.1063/5.0248205","url":null,"abstract":"This paper presents a polarization-insensitive microwave power receiving composite metasurface array. The composite array consists of a reflection phase gradient metasurface array and a horizontal omnidirectional antenna, with a central operating frequency of 5.8 GHz. The reflection phase gradient metasurface array elements are insensitive to the polarization of the incident wave and are arranged radially around the array center. This configuration creates a radial reflection phase gradient that efficiently converts incident plane waves of different polarizations into surface waves converging toward the center. The surface wave energy is then extracted by the horizontal omnidirectional antenna and converted into direct current (DC) by a rectifier. Numerical simulations demonstrate that the composite array maintains effective surface wave excitation and propagation toward the center for both circularly polarized and various horizontally polarized plane waves, achieving a plane wave-to-surface wave conversion efficiency of 74.89%. Experimental validation shows that the proposed array achieves a maximum energy collection efficiency of 62.23% and an RF-DC conversion efficiency of 39.96% over a broad frequency range of 5.6–6.0 GHz. This study achieves polarization insensitivity while simultaneously enhancing the operational efficiency of microwave energy receivers. The results offer a valuable design reference for leveraging reflection phase gradient arrays in wireless power transfer applications.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"10 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lei Wang, Tengfei Huang, Ruipeng Hou, Baocheng Yang
Rare earth (RE) ions are important dopants to modulate semiconductor properties because of their abundant energy levels. Herein, a simple Er–Yb co-doping strategy was developed to enhance the near-infrared optoelectronic properties of SnS2 nanosheets. The constructed device based on Er–Yb co-doping SnS2 has a detectivity of ∼4.97 × 108 Jones at 980 nm. The enhanced photoresponse of the doped system at 980 nm could be attributed to the upconversion behavior of the Er–Yb ion pairs. The Yb3+ ions as sensitizers significantly enhance the upconversion emission and near-infrared photoresponse properties of the material. The energy transfer from Yb3+ to Er3+ ions can occur between different layers of co-doping nanosheets by investigating the properties of the constructed SnS2:Er/SnS2:Yb homojunction nanosheets. Density functional theory calculations reveal that Er or Yb doping introduces slight structural and charge distribution changes owing to the similarity in the metal–atom coordination structure between SnS2 and RE sulfide. Our study demonstrates that RE doping is an effective way to improve the near-infrared photoresponse of 2D materials and clarifies the relationship between luminescence and photoelectric properties.
{"title":"Enhanced near-infrared photoresponse of SnS2 nanosheets by Er–Yb co-doping","authors":"Lei Wang, Tengfei Huang, Ruipeng Hou, Baocheng Yang","doi":"10.1063/5.0249415","DOIUrl":"https://doi.org/10.1063/5.0249415","url":null,"abstract":"Rare earth (RE) ions are important dopants to modulate semiconductor properties because of their abundant energy levels. Herein, a simple Er–Yb co-doping strategy was developed to enhance the near-infrared optoelectronic properties of SnS2 nanosheets. The constructed device based on Er–Yb co-doping SnS2 has a detectivity of ∼4.97 × 108 Jones at 980 nm. The enhanced photoresponse of the doped system at 980 nm could be attributed to the upconversion behavior of the Er–Yb ion pairs. The Yb3+ ions as sensitizers significantly enhance the upconversion emission and near-infrared photoresponse properties of the material. The energy transfer from Yb3+ to Er3+ ions can occur between different layers of co-doping nanosheets by investigating the properties of the constructed SnS2:Er/SnS2:Yb homojunction nanosheets. Density functional theory calculations reveal that Er or Yb doping introduces slight structural and charge distribution changes owing to the similarity in the metal–atom coordination structure between SnS2 and RE sulfide. Our study demonstrates that RE doping is an effective way to improve the near-infrared photoresponse of 2D materials and clarifies the relationship between luminescence and photoelectric properties.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"52 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is a challenge to find the relationship between the microscopic property of atoms in monolayers and the macroscopic piezoelectricity of monolayer. By first-principles calculation, we find not only the super-dipole moment (SDM) effect but also the electronegative polar moments (EPMs) effect, which can lead to the remarkable piezoelectricity in TiSXY monolayers. The SDM and EPM effects can deepen the understanding of the piezoelectric physical mechanism and provide the design strategy for ultrathin nano-devices.
{"title":"Enhanced piezoelectricity in TiSXY monolayers based on electronegative polar moments effect","authors":"Dai-Song Tang, Yu-Qing Luo, Dan-Yang Zhu, Jun-Hui Wang, Xian-Tong Shao, Shou-Xin Cui, Xiao-Chun Wang","doi":"10.1063/5.0251468","DOIUrl":"https://doi.org/10.1063/5.0251468","url":null,"abstract":"It is a challenge to find the relationship between the microscopic property of atoms in monolayers and the macroscopic piezoelectricity of monolayer. By first-principles calculation, we find not only the super-dipole moment (SDM) effect but also the electronegative polar moments (EPMs) effect, which can lead to the remarkable piezoelectricity in TiSXY monolayers. The SDM and EPM effects can deepen the understanding of the piezoelectric physical mechanism and provide the design strategy for ultrathin nano-devices.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"52 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yixiao Deng, Wenbin Qiu, Kaiyi Luo, An Li, Kai Luo, Geyang Wu, Pingping Qian, Haowen Chen, Lei Yang, Jun Tang
Bismuth telluride (Bi2Te3), renowned for its exceptional thermoelectric (TE) properties near room temperature, is used in extreme environments such as deep space exploration, leading to extensive attention on the radiation-induced defects to Bi2Te3. However, the evolution of point defects during gamma (γ)-irradiation is still poorly understood. In this paper, we report the evolution of point defects in Bi2Te3 materials subjected to varying doses of γ-irradiation and their impact on TE performance. Precisely, Bi0.5Sb1.5Te3 and Bi2Te2.7Se0.3 materials, along with TE modules, were fabricated and subsequently subjected to γ-irradiation. The segregation of Te elements in Bi2Te3 was observed under low irradiation dose, attributing to the formation of interstitial atom–vacancy pair of Te induced by γ-irradiation. In addition, the formation of point defects has a positive relation with the irradiation dose. The positron annihilation (PA) measurements revealed that the number of vacancies in Bi2Te3 diminished with increasing irradiation dose. The accompanying changes in carrier concentration (nH) and mobility (μH) suggest that γ-ray drives Bi atoms to occupy Te vacancies, forming antisite defects. The TE performance of Bi2Te3 was subsequently evaluated, and the findings revealed a strong correlation with the evolution of point defects. This study provides insights into the damage mechanisms and property alterations of Bi2Te3 materials under γ-irradiation.
{"title":"Evolution of point defects in Bi2Te3-based materials and performance of thermoelectric modules subjected to γ -irradiation","authors":"Yixiao Deng, Wenbin Qiu, Kaiyi Luo, An Li, Kai Luo, Geyang Wu, Pingping Qian, Haowen Chen, Lei Yang, Jun Tang","doi":"10.1063/5.0245402","DOIUrl":"https://doi.org/10.1063/5.0245402","url":null,"abstract":"Bismuth telluride (Bi2Te3), renowned for its exceptional thermoelectric (TE) properties near room temperature, is used in extreme environments such as deep space exploration, leading to extensive attention on the radiation-induced defects to Bi2Te3. However, the evolution of point defects during gamma (γ)-irradiation is still poorly understood. In this paper, we report the evolution of point defects in Bi2Te3 materials subjected to varying doses of γ-irradiation and their impact on TE performance. Precisely, Bi0.5Sb1.5Te3 and Bi2Te2.7Se0.3 materials, along with TE modules, were fabricated and subsequently subjected to γ-irradiation. The segregation of Te elements in Bi2Te3 was observed under low irradiation dose, attributing to the formation of interstitial atom–vacancy pair of Te induced by γ-irradiation. In addition, the formation of point defects has a positive relation with the irradiation dose. The positron annihilation (PA) measurements revealed that the number of vacancies in Bi2Te3 diminished with increasing irradiation dose. The accompanying changes in carrier concentration (nH) and mobility (μH) suggest that γ-ray drives Bi atoms to occupy Te vacancies, forming antisite defects. The TE performance of Bi2Te3 was subsequently evaluated, and the findings revealed a strong correlation with the evolution of point defects. This study provides insights into the damage mechanisms and property alterations of Bi2Te3 materials under γ-irradiation.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"79 5 Pt 1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Single-walled carbon nanotubes (SWCNTs) are promising candidates for use in thermoelectric generators (TEGs) to power Internet of Things (IoT) sensors. For practical applications, the major challenge for SWCNTs is improving the thermoelectric performance and thermal durability of n-type SWCNT films. Here, SWCNT inks were prepared using a dopant, which is a cationic surfactant of dimethyldioctadecylammonium chloride (DODMAC), by changing the mass ratio of DODMAC/SWCNT. The SWCNT films were fabricated by vacuum filtering, followed by heat treatment at 423 K. The in-plane thermoelectric properties were measured at 300 K, and the Seebeck coefficient changed from positive to negative values when the DODMAC/SWCNT was 10−2. The highest dimensionless figure-of-merit, ZT, of 1.0 × 10−2 was exhibited at a DODMAC/SWCNT of 80, which was close to saturation concentration. This ZT was achieved mainly because the thermal conductivity decreased significantly to 0.16 W/(m · K), and it is currently one of the highest values among those of n-type SWCNT films with various dopants. To demonstrate power generation, we fabricated a SWCNT-TEG consisting of n-type SWCNT films with the highest ZT. The SWCNT-TEG exhibited an output voltage of 24 mV and a maximum power of 0.9 μW at a temperature difference of 80 K. Furthermore, to investigate the thermal durability of n-type SWCNT films, thermal cycling tests were performed at temperatures ranging from 300 to 423 K. The SWCNT film with a DODMAC/SWCNT of 80 exhibited the highest durability. These findings will contribute to the widespread use of SWCNT-TEGs as power sources for IoT sensors.
{"title":"High thermal durability and thermoelectric performance with ultra-low thermal conductivity in n-type single-walled carbon nanotube films by controlling dopant concentration with cationic surfactant","authors":"Hisatoshi Yamamoto, Takuya Amezawa, Yutaro Okano, Koki Hoshino, Shuya Ochiai, Kento Sunaga, Shugo Miyake, Masayuki Takashiri","doi":"10.1063/5.0252016","DOIUrl":"https://doi.org/10.1063/5.0252016","url":null,"abstract":"Single-walled carbon nanotubes (SWCNTs) are promising candidates for use in thermoelectric generators (TEGs) to power Internet of Things (IoT) sensors. For practical applications, the major challenge for SWCNTs is improving the thermoelectric performance and thermal durability of n-type SWCNT films. Here, SWCNT inks were prepared using a dopant, which is a cationic surfactant of dimethyldioctadecylammonium chloride (DODMAC), by changing the mass ratio of DODMAC/SWCNT. The SWCNT films were fabricated by vacuum filtering, followed by heat treatment at 423 K. The in-plane thermoelectric properties were measured at 300 K, and the Seebeck coefficient changed from positive to negative values when the DODMAC/SWCNT was 10−2. The highest dimensionless figure-of-merit, ZT, of 1.0 × 10−2 was exhibited at a DODMAC/SWCNT of 80, which was close to saturation concentration. This ZT was achieved mainly because the thermal conductivity decreased significantly to 0.16 W/(m · K), and it is currently one of the highest values among those of n-type SWCNT films with various dopants. To demonstrate power generation, we fabricated a SWCNT-TEG consisting of n-type SWCNT films with the highest ZT. The SWCNT-TEG exhibited an output voltage of 24 mV and a maximum power of 0.9 μW at a temperature difference of 80 K. Furthermore, to investigate the thermal durability of n-type SWCNT films, thermal cycling tests were performed at temperatures ranging from 300 to 423 K. The SWCNT film with a DODMAC/SWCNT of 80 exhibited the highest durability. These findings will contribute to the widespread use of SWCNT-TEGs as power sources for IoT sensors.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"21 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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