Band structure engineering continues to be pursued in solid-state physics. Here, we study Dirac semimetal (DSM) thin films under in-plane magnetic fields and uncover an extrinsic mechanism for band control. In DSM films, quantum tunneling between surface states on opposing surfaces opens a hybridization gap. We demonstrate that the in-plane magnetic field and the intersurface hybridization intertwine to invert the band structure, driving a phase transition from a band insulator to a nodal-ring semimetal. Highlighting the key role of band inversion, we further analyze the magnetoresponse in the nodal-ring regime, and find the Landau levels experience a serpentine oscillation and exhibit multiple crossings. These crossings mark a rich variety of topological phases, encompassing the helical quantum Hall insulator, spin-filtered quantum Hall insulator, and normal band insulator. Our results establish a unique pathway of band inversion via external fields, providing a controllable approach to engineer energy bands and manipulate topological states in DSMs.
{"title":"Engineering band topology of Dirac semimetal films via in-plane magnetic fields","authors":"Gang Wang","doi":"10.1063/5.0318792","DOIUrl":"https://doi.org/10.1063/5.0318792","url":null,"abstract":"Band structure engineering continues to be pursued in solid-state physics. Here, we study Dirac semimetal (DSM) thin films under in-plane magnetic fields and uncover an extrinsic mechanism for band control. In DSM films, quantum tunneling between surface states on opposing surfaces opens a hybridization gap. We demonstrate that the in-plane magnetic field and the intersurface hybridization intertwine to invert the band structure, driving a phase transition from a band insulator to a nodal-ring semimetal. Highlighting the key role of band inversion, we further analyze the magnetoresponse in the nodal-ring regime, and find the Landau levels experience a serpentine oscillation and exhibit multiple crossings. These crossings mark a rich variety of topological phases, encompassing the helical quantum Hall insulator, spin-filtered quantum Hall insulator, and normal band insulator. Our results establish a unique pathway of band inversion via external fields, providing a controllable approach to engineer energy bands and manipulate topological states in DSMs.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"78 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146095611","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}
Connor E. Murphy, Cody Jessup, Tahereh Naderishahab, Yateendra Sihag, Max M. Fields, Leonardo R. Werneck, Zachariah B. Etienne, Brian D'Urso
We demonstrate an ultra-low dissipation, one-dimensional mechanical oscillator formed by levitating a millimeter-scale composite graphite rod in a room-temperature magneto-gravitational trap. The trap's magnetic field geometry, based on a linear quadrupole, eliminates first-order field gradients in the axial direction, yielding a low oscillation frequency with ultra-low eddy-current losses. Direct ringdown measurements under vacuum compare the damping of the vertical and axial motion; while the vertical motion damps in seconds, the axial motion damps with a time constant of over 5 days. Analysis reveals that this dramatic difference in damping is a result of the symmetry of the magnetic field and the anisotropy of the trap strength. The results are remarkably robust, demonstrating a potential platform for inertial and gravitational sensing.
{"title":"Ultra-low damping of the translational motion of a composite graphite rod in a magneto-gravitational trap","authors":"Connor E. Murphy, Cody Jessup, Tahereh Naderishahab, Yateendra Sihag, Max M. Fields, Leonardo R. Werneck, Zachariah B. Etienne, Brian D'Urso","doi":"10.1063/5.0287198","DOIUrl":"https://doi.org/10.1063/5.0287198","url":null,"abstract":"We demonstrate an ultra-low dissipation, one-dimensional mechanical oscillator formed by levitating a millimeter-scale composite graphite rod in a room-temperature magneto-gravitational trap. The trap's magnetic field geometry, based on a linear quadrupole, eliminates first-order field gradients in the axial direction, yielding a low oscillation frequency with ultra-low eddy-current losses. Direct ringdown measurements under vacuum compare the damping of the vertical and axial motion; while the vertical motion damps in seconds, the axial motion damps with a time constant of over 5 days. Analysis reveals that this dramatic difference in damping is a result of the symmetry of the magnetic field and the anisotropy of the trap strength. The results are remarkably robust, demonstrating a potential platform for inertial and gravitational sensing.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"8 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146095613","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}
Anand Ithepalli, Saumya Vashishtha, Naomi Pieczulewski, Qiao Liu, Amit Rohan Rajapurohita, Matthew Barone, Darrell Schlom, David A. Muller, Huili Grace Xing, Debdeep Jena
We report the structural and electronic properties of niobium nitride (NbN) thin films grown by molecular beam epitaxy on c-plane sapphire with miscut angles of 0.5°, 2°, 4°, and 10° toward m-axis. X-ray diffraction scans reveal that the full width at half maximum of the rocking curves around the 1 1 1 reflection of these NbN films decreases with increasing miscut. Starting from 76 arcsecs on 0.5° miscut, the FWHM reduces to almost 20 arcsecs on 10° miscut sapphire, indicating improved structural quality. Scanning transmission electron microscopy images indicate that NbN on c-sapphire has around 10 nm critical thickness, irrespective of the substrate miscut, above which it turns columnar. The improved structural property is correlated with a marginal increment in superconducting transition temperature Tc from 12.1 K for NbN on 0.5° miscut sapphire to 12.5 K for NbN on 10° miscut sapphire.
{"title":"Effect of substrate miscut angle on critical thickness, structural and electronic properties of MBE-grown NbN films on c-plane sapphire","authors":"Anand Ithepalli, Saumya Vashishtha, Naomi Pieczulewski, Qiao Liu, Amit Rohan Rajapurohita, Matthew Barone, Darrell Schlom, David A. Muller, Huili Grace Xing, Debdeep Jena","doi":"10.1063/5.0312575","DOIUrl":"https://doi.org/10.1063/5.0312575","url":null,"abstract":"We report the structural and electronic properties of niobium nitride (NbN) thin films grown by molecular beam epitaxy on c-plane sapphire with miscut angles of 0.5°, 2°, 4°, and 10° toward m-axis. X-ray diffraction scans reveal that the full width at half maximum of the rocking curves around the 1 1 1 reflection of these NbN films decreases with increasing miscut. Starting from 76 arcsecs on 0.5° miscut, the FWHM reduces to almost 20 arcsecs on 10° miscut sapphire, indicating improved structural quality. Scanning transmission electron microscopy images indicate that NbN on c-sapphire has around 10 nm critical thickness, irrespective of the substrate miscut, above which it turns columnar. The improved structural property is correlated with a marginal increment in superconducting transition temperature Tc from 12.1 K for NbN on 0.5° miscut sapphire to 12.5 K for NbN on 10° miscut sapphire.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"94 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146095612","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}
Minho Kim, Dat Q. Tran, Plamen P. Paskov, Uiho Choi, Okhyun Nam, Vanya Darakchieva
We investigate the influence of AlN buffer thickness on the structural, electrical, and thermal properties of AlGaN/GaN high-electron mobility transistors (HEMTs) grown on semi-insulating SiC substrates by metal-organic chemical vapor deposition. X-ray diffraction and atomic force microscopy reveal that while thin AlN layers (120 nm) exhibit compressive strain and smooth step-flow surfaces, thicker single-layer buffers (550 nm) develop tensile strain and increased surface roughness. Multi-layer buffer structures up to 2 μm alleviate strain and maintain surface integrity. Low-temperature Hall measurements confirm that electron mobility decreases with increasing interface roughness, with the highest mobility observed in the structure with a thin AlN buffer. Transient thermoreflectance measurements show that thermal conductivity (ThC) of the AlN buffer increases with the thickness, reaching 190 W/m.K at 300 K for the 2 μm buffer layer, which is approximately 60% of the bulk AlN ThC value. These results highlight the importance of optimizing AlN buffer design to balance strain relaxation, thermal management, and carrier transport for high-performance GaN-based HEMTs.
{"title":"Impact of AlN buffer thickness on electrical and thermal characteristics of AlGaN/GaN/AlN HEMTs","authors":"Minho Kim, Dat Q. Tran, Plamen P. Paskov, Uiho Choi, Okhyun Nam, Vanya Darakchieva","doi":"10.1063/5.0310464","DOIUrl":"https://doi.org/10.1063/5.0310464","url":null,"abstract":"We investigate the influence of AlN buffer thickness on the structural, electrical, and thermal properties of AlGaN/GaN high-electron mobility transistors (HEMTs) grown on semi-insulating SiC substrates by metal-organic chemical vapor deposition. X-ray diffraction and atomic force microscopy reveal that while thin AlN layers (120 nm) exhibit compressive strain and smooth step-flow surfaces, thicker single-layer buffers (550 nm) develop tensile strain and increased surface roughness. Multi-layer buffer structures up to 2 μm alleviate strain and maintain surface integrity. Low-temperature Hall measurements confirm that electron mobility decreases with increasing interface roughness, with the highest mobility observed in the structure with a thin AlN buffer. Transient thermoreflectance measurements show that thermal conductivity (ThC) of the AlN buffer increases with the thickness, reaching 190 W/m.K at 300 K for the 2 μm buffer layer, which is approximately 60% of the bulk AlN ThC value. These results highlight the importance of optimizing AlN buffer design to balance strain relaxation, thermal management, and carrier transport for high-performance GaN-based HEMTs.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"2 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072364","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}
Fabricating quantum-dot (QD) light-emitting diode (LED) arrays typically relies on direct QD patterning or costly color filters (CFs), highlighting the need for cost-effective patterning techniques to achieve high-efficiency pixelated QLEDs. This study presents a bi-color-converting cavity that transforms yellow emissions from non-patterned mixed red and green QDs into saturated red and green emissions by adjusting the thickness of the indium-zinc-oxide phase tuning layer. Excluding blue QDs with low quantum yields and high injection barriers, this approach is expected to achieve excellent device performance tailored for specific outdoor display applications. The cavity yellow QLEDs exhibit maximum current efficiencies of 28.20 and 36.32 cd/A for red and green emissions, representing enhancements of 144% and 148% over CF yellow QLEDs, respectively. These improvements stem from the bi-color-converting cavity, which enhances the forward emissions in the cavity yellow QLED and redistributes exciton energy in mixed QDs by modulating the energy transfer. Furthermore, bi-color pixelated QLEDs with a resolution of 423 pixels per inch have been demonstrated. This bi-color-converting cavity technique relies on established photolithography techniques and holds great potential in high-performance and high-resolution display applications.
{"title":"Highly efficient pixelated quantum-dot light-emitting diodes enabled by bi-color-converting cavities","authors":"Peili Gao, Haohao Yang, Zhen Yin, Cuixia Yuan, Qiang Su, Shuming Chen","doi":"10.1063/5.0307943","DOIUrl":"https://doi.org/10.1063/5.0307943","url":null,"abstract":"Fabricating quantum-dot (QD) light-emitting diode (LED) arrays typically relies on direct QD patterning or costly color filters (CFs), highlighting the need for cost-effective patterning techniques to achieve high-efficiency pixelated QLEDs. This study presents a bi-color-converting cavity that transforms yellow emissions from non-patterned mixed red and green QDs into saturated red and green emissions by adjusting the thickness of the indium-zinc-oxide phase tuning layer. Excluding blue QDs with low quantum yields and high injection barriers, this approach is expected to achieve excellent device performance tailored for specific outdoor display applications. The cavity yellow QLEDs exhibit maximum current efficiencies of 28.20 and 36.32 cd/A for red and green emissions, representing enhancements of 144% and 148% over CF yellow QLEDs, respectively. These improvements stem from the bi-color-converting cavity, which enhances the forward emissions in the cavity yellow QLED and redistributes exciton energy in mixed QDs by modulating the energy transfer. Furthermore, bi-color pixelated QLEDs with a resolution of 423 pixels per inch have been demonstrated. This bi-color-converting cavity technique relies on established photolithography techniques and holds great potential in high-performance and high-resolution display applications.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"117 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072362","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}
With the advent of the information age, the demand for memristors in neuromorphic circuits and artificial intelligence has become increasingly urgent. In this Letter, analog- and digital-type resistive switching is concurrently obtained in quasi-2D perovskite memristors by regulating elemental composition and crystallinity. For the high Pb sample treated with MACl, continuous enhancement and suppression of analog-type conductance are achieved under direct current voltage sweep and voltage pulse stimulation, which shows 62.2% enhancement and 68.4% inhibition after long-term synaptic plasticity. The analog-type memristor also presents good spike voltage-dependent and frequency-dependent plasticities with a paired-pulse facilitation index of 55.5%. In contrast, for the low Pb sample treated with MACl, the lattice distortion and crystal defects are further decreased, leading to a sudden change of digital-type resistance in the current−voltage curve. The digital-type memristor has very good non-volatile memory performance with a resistance-to-switch ratio of 5 × 103, an endurance of more than 2100 cycles, a retention characteristic of more than 104 s, a statistical set voltage of 0.55 V, and a reset voltage of −1 V. This study elucidates analog and digital resistive switching mechanism in quasi-2D perovskites and demonstrates their significant potential and prospects in neuronal circuit and storage-computing technologies.
{"title":"Achieving analog and digital resistive switching for quasi-2D perovskite memristors by compositional regulation and crystalline manipulation","authors":"Chenhui Su, Xuemiao Wen, Wen Lei, Guanglu Lin, Tianjiao Liu, Yijing Fan, Yibo Peng, Cuiying Hu, Zhenfang Tang, Zhichao Chen, Shuyan Fang, Renqiang Yang, Dongping Yang, Xingui Tang, Lintao Hou","doi":"10.1063/5.0276050","DOIUrl":"https://doi.org/10.1063/5.0276050","url":null,"abstract":"With the advent of the information age, the demand for memristors in neuromorphic circuits and artificial intelligence has become increasingly urgent. In this Letter, analog- and digital-type resistive switching is concurrently obtained in quasi-2D perovskite memristors by regulating elemental composition and crystallinity. For the high Pb sample treated with MACl, continuous enhancement and suppression of analog-type conductance are achieved under direct current voltage sweep and voltage pulse stimulation, which shows 62.2% enhancement and 68.4% inhibition after long-term synaptic plasticity. The analog-type memristor also presents good spike voltage-dependent and frequency-dependent plasticities with a paired-pulse facilitation index of 55.5%. In contrast, for the low Pb sample treated with MACl, the lattice distortion and crystal defects are further decreased, leading to a sudden change of digital-type resistance in the current−voltage curve. The digital-type memristor has very good non-volatile memory performance with a resistance-to-switch ratio of 5 × 103, an endurance of more than 2100 cycles, a retention characteristic of more than 104 s, a statistical set voltage of 0.55 V, and a reset voltage of −1 V. This study elucidates analog and digital resistive switching mechanism in quasi-2D perovskites and demonstrates their significant potential and prospects in neuronal circuit and storage-computing technologies.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"15 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072555","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}
Two-dimensional MXenes exhibit exceptional magnetic and topological properties, making them promising candidates for spintronic devices. Herein, we investigate the electronic and magnetic characteristics of HHH- and HTT-phase bimetallic VTiCF2 monolayers via first-principles calculations. Our results show that the HHH-phase VTiCF2 monolayer is a robust out-of-plane ferromagnetic (FM) half-metal with an ultrahigh Curie temperature (TC) of 1020 K. Incorporating spin–orbit coupling transforms it into a quantum anomalous Hall (QAH) insulator with a 36.59 meV bandgap and Chern number C = 1. In contrast, the HTT-phase is a ferrimagnetic (FIM) nodal-line semimetal with in-plane magnetization and TC = 494 K. Notably, the HHH-phase retains its QAH properties under biaxial strains, while the HTT-phase undergoes FIM-to-FM transition at 3% biaxial tensile strain. These findings expand the functional MXene libraries and provide a candidate for room-temperature spintronic devices.
{"title":"Quantum anomalous Hall state and Weyl nodal line semimetal state in room-temperature magnetic VTiCF2 monolayer","authors":"Jiahui Li, Yinong Liu, Yuqing Mao, Jie Li, Lijuan Meng, Xiaojing Yao, Ailei He, Xiuyun Zhang","doi":"10.1063/5.0307107","DOIUrl":"https://doi.org/10.1063/5.0307107","url":null,"abstract":"Two-dimensional MXenes exhibit exceptional magnetic and topological properties, making them promising candidates for spintronic devices. Herein, we investigate the electronic and magnetic characteristics of HHH- and HTT-phase bimetallic VTiCF2 monolayers via first-principles calculations. Our results show that the HHH-phase VTiCF2 monolayer is a robust out-of-plane ferromagnetic (FM) half-metal with an ultrahigh Curie temperature (TC) of 1020 K. Incorporating spin–orbit coupling transforms it into a quantum anomalous Hall (QAH) insulator with a 36.59 meV bandgap and Chern number C = 1. In contrast, the HTT-phase is a ferrimagnetic (FIM) nodal-line semimetal with in-plane magnetization and TC = 494 K. Notably, the HHH-phase retains its QAH properties under biaxial strains, while the HTT-phase undergoes FIM-to-FM transition at 3% biaxial tensile strain. These findings expand the functional MXene libraries and provide a candidate for room-temperature spintronic devices.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"143 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072366","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}
Wenzhuo Zhuang, Wenxuan Sun, Ruijie Xu, Anke Song, Zhihao Li, Yifan Zhang, Yu Li, Di Wang, Guozhong Xing, Rong Zhang, Xuefeng Wang
High-speed and low-power spin–orbit torque (SOT) devices necessitate materials with high spin-to-charge conversion efficiency. Transition metal dichalcogenides (TMDs) have emerged as a promising platform for SOT research due to their topological features and band structure tunability. In this work, we fabricate large-area PtSe2 films via a two-step method and demonstrate a thickness-dependent semiconductor-to-semimetal transition. The spin-to-charge conversion efficiency of PtSe2 films exhibits an approximately sixty-fold enhancement across this semiconductor-to-semimetal transition. This work provides an alternative approach for modulating spin-to-charge conversion in TMDs and advances their potential applications in spintronics.
{"title":"Tunable spin-to-charge conversion across semiconductor–semimetal transition in large-area PtSe2 thin films","authors":"Wenzhuo Zhuang, Wenxuan Sun, Ruijie Xu, Anke Song, Zhihao Li, Yifan Zhang, Yu Li, Di Wang, Guozhong Xing, Rong Zhang, Xuefeng Wang","doi":"10.1063/5.0307058","DOIUrl":"https://doi.org/10.1063/5.0307058","url":null,"abstract":"High-speed and low-power spin–orbit torque (SOT) devices necessitate materials with high spin-to-charge conversion efficiency. Transition metal dichalcogenides (TMDs) have emerged as a promising platform for SOT research due to their topological features and band structure tunability. In this work, we fabricate large-area PtSe2 films via a two-step method and demonstrate a thickness-dependent semiconductor-to-semimetal transition. The spin-to-charge conversion efficiency of PtSe2 films exhibits an approximately sixty-fold enhancement across this semiconductor-to-semimetal transition. This work provides an alternative approach for modulating spin-to-charge conversion in TMDs and advances their potential applications in spintronics.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"54 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072363","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}
This paper reports on high-performance Ku-band AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) on a Si substrate for low-voltage applications. Benefiting from the 7 nm thin-barrier AlGaN and the high-stress low pressure chemical vapor deposition (LPCVD) SiN passivation, a high saturation current of 1.56 A/mm, a low on-resistance of 0.87 Ω mm, and a small current collapse at 20 V drain quiescent condition of 2.1% were achieved. Enabled by the ability of LPCVD-SiN to allow the devices to withstand high-temperature conditions during gate dielectric deposition and post-deposition annealing, a 7 nm plasma-enhanced atomic layer deposition SiN was employed as the gate dielectric. The MIS-HEMTs show low leakage current and a large on/off current ratio. At 18 GHz, the devices achieve a peak power-added efficiency (PAE) exceeding 60% at a low drain voltage (Vds) range of 5–12 V. A peak PAE of 65.1% (Vds = 8 V) and a maximum output power density (Pout,max) of 3.46 W/mm (Vds = 12 V) were demonstrated, which are the highest PAE and Pout,max at the same operating voltage reported by GaN HEMTs in Ku-band. These excellent results show that the MIS-HEMTs have great potential in Ku-band low-voltage applications.
{"title":"High-performance Ku-band thin-barrier AlGaN/GaN MIS-HEMTs on Si using high-stress LPCVD-SiN passivation for low-voltage applications","authors":"Jiejie Zhu, Mengdi Li, Qing Zhu, Wanshuo Liao, Sheng Zhang, Yuchen Qian, Yichong Ding, Yiwei Wang, Lingjie Qin, Yuxi Zhou, Bowen Zhang, Ke Wei, Xinyu Liu, Yue Hao, Xiaohua Ma","doi":"10.1063/5.0297174","DOIUrl":"https://doi.org/10.1063/5.0297174","url":null,"abstract":"This paper reports on high-performance Ku-band AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) on a Si substrate for low-voltage applications. Benefiting from the 7 nm thin-barrier AlGaN and the high-stress low pressure chemical vapor deposition (LPCVD) SiN passivation, a high saturation current of 1.56 A/mm, a low on-resistance of 0.87 Ω mm, and a small current collapse at 20 V drain quiescent condition of 2.1% were achieved. Enabled by the ability of LPCVD-SiN to allow the devices to withstand high-temperature conditions during gate dielectric deposition and post-deposition annealing, a 7 nm plasma-enhanced atomic layer deposition SiN was employed as the gate dielectric. The MIS-HEMTs show low leakage current and a large on/off current ratio. At 18 GHz, the devices achieve a peak power-added efficiency (PAE) exceeding 60% at a low drain voltage (Vds) range of 5–12 V. A peak PAE of 65.1% (Vds = 8 V) and a maximum output power density (Pout,max) of 3.46 W/mm (Vds = 12 V) were demonstrated, which are the highest PAE and Pout,max at the same operating voltage reported by GaN HEMTs in Ku-band. These excellent results show that the MIS-HEMTs have great potential in Ku-band low-voltage applications.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"118 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072367","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}
Two-dimensional (2D) carbon allotropes for high-performance electrode materials in lithium-ion batteries (LIBs) are attracting a great deal of research interest due to their unique architectures. Herein, we perform the first-principles calculations to systematically investigate the feasibility of 2D sp–sp2 hybridized THD-C (tetra-, hexa-, and dodeca-membered rings), as a potential anode for LIBs. Our simulations indicate that two spatially adjacent acetylenic bonds engender a modest Li–C coupling via the cooperative cation–π interaction driven by partial electron transfer, which exhibits a suitable Li adsorption energy of –0.78 eV. 2D THD-C is proven to be a favorable anode material that offers a high theoretical capacity (1116.7 mAh/g), a low Li diffusion barrier (0.49 eV), and a moderate open-circuit voltage (0.40 V). Furthermore, it retains a small volume change (∼3%) as well as favorable structural and thermal stability even at maximum Li concentration. Overall, those findings not only provide an in-depth mechanistic insight but also extend an effective method to search for high-performance anode materials in advancing LIB technology.
{"title":"The cooperative cation– π interaction in two-dimensional THD-C as a high-capacity anode material for Li-ion batteries","authors":"Zihao Wang, Haoxuan Chen, Zhenjie Zhao, Huadong Zeng, Xinlu Cheng","doi":"10.1063/5.0312468","DOIUrl":"https://doi.org/10.1063/5.0312468","url":null,"abstract":"Two-dimensional (2D) carbon allotropes for high-performance electrode materials in lithium-ion batteries (LIBs) are attracting a great deal of research interest due to their unique architectures. Herein, we perform the first-principles calculations to systematically investigate the feasibility of 2D sp–sp2 hybridized THD-C (tetra-, hexa-, and dodeca-membered rings), as a potential anode for LIBs. Our simulations indicate that two spatially adjacent acetylenic bonds engender a modest Li–C coupling via the cooperative cation–π interaction driven by partial electron transfer, which exhibits a suitable Li adsorption energy of –0.78 eV. 2D THD-C is proven to be a favorable anode material that offers a high theoretical capacity (1116.7 mAh/g), a low Li diffusion barrier (0.49 eV), and a moderate open-circuit voltage (0.40 V). Furthermore, it retains a small volume change (∼3%) as well as favorable structural and thermal stability even at maximum Li concentration. Overall, those findings not only provide an in-depth mechanistic insight but also extend an effective method to search for high-performance anode materials in advancing LIB technology.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"43 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072556","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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