Pub Date : 2026-02-04DOI: 10.1016/j.jlumin.2026.121778
Anis Naveed, Muhammad Usman, Jamshad Bashir, Anuda Bibi
In this numerical study, we propose a dual tunnel junction (TJ)-based GaN/InGaN Green light-emitting diode (LED) structure designed to enhance carrier confinement and mitigate polarization-induced electric fields. By integrating tunnel junctions on both sides of the active region, the proposed device exhibits significant improvements in carrier concentrations—37% for electrons and 5.45% for holes—compared to the reference LED. As a result, the internal quantum efficiency (IQE) increases to 75%, surpassing the 54% observed in conventional design. Moreover, the proposed LED demonstrates a reduced efficiency droop of 37%, compared to 5% in the reference device, under a current density of 50 A/cm2. The emission intensity is also enhanced by approximately 1.5 times, validating the effectiveness of the dual-TJ configuration in achieving high-efficiency green LED performance.
在这项数值研究中，我们提出了一种基于双隧道结（TJ）的GaN/InGaN绿色发光二极管（LED）结构，旨在增强载流子约束和减轻极化感应电场。通过在有源区两侧集成隧道结，与参考LED相比，该器件的载流子浓度显著提高，电子载流子浓度为37%，空穴载流子浓度为5.45%。因此，内部量子效率（IQE）增加到75%，超过了传统设计中观察到的54%。此外，在电流密度为50 a /cm2的情况下，该LED的效率下降了37%，而参考器件的效率下降了5%。发射强度也提高了约1.5倍，验证了双tj配置在实现高效绿色LED性能方面的有效性。
{"title":"Dual tunnel junction engineering for high-IQE GaN/InGaN green LEDs","authors":"Anis Naveed, Muhammad Usman, Jamshad Bashir, Anuda Bibi","doi":"10.1016/j.jlumin.2026.121778","DOIUrl":"10.1016/j.jlumin.2026.121778","url":null,"abstract":"<div><div>In this numerical study, we propose a dual tunnel junction (TJ)-based GaN/InGaN Green light-emitting diode (LED) structure designed to enhance carrier confinement and mitigate polarization-induced electric fields. By integrating tunnel junctions on both sides of the active region, the proposed device exhibits significant improvements in carrier concentrations—37% for electrons and 5.45% for holes—compared to the reference LED. As a result, the internal quantum efficiency (IQE) increases to 75%, surpassing the 54% observed in conventional design. Moreover, the proposed LED demonstrates a reduced efficiency droop of 37%, compared to 5% in the reference device, under a current density of 50 A/cm<sup>2</sup>. The emission intensity is also enhanced by approximately 1.5 times, validating the effectiveness of the dual-TJ configuration in achieving high-efficiency green LED performance.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"293 ","pages":"Article 121778"},"PeriodicalIF":3.6,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-02-04DOI: 10.1016/j.jlumin.2026.121788
Aiman Fatima, Muhammad Usman, Shazma Ali, Anis Naveed, Anuda Bibi, Haseena Noor
In this work, a wedge-shaped p-AlGaN layer (WPL) with bidirectional Al composition grading is introduced to overcome the limitations of conventional rectangular p-type AlGaN layer (CPL). The graded Al composition reduces the Mg acceptor activation energy, allowing a greater fraction of Mg dopants to ionize and thereby improving hole transport. Numerical simulations demonstrate that the proposed design increases the hole and electron concentrations in the active region by 7% and 4%, respectively, leading to a more uniform carrier distribution within the quantum wells. As a result, the radiative recombination rate is increased by 23%, and the internal quantum efficiency (IQE) is enhanced from 52% to 80.4%. These results highlight compositionally graded, wedge-shaped p-AlGaN layers as an effective design strategy for realizing high-performance AlGaN-based DUV LEDs.
{"title":"Engineered p-type AlGaN layer for enhanced deep ultraviolet light-emitting diodes performance","authors":"Aiman Fatima, Muhammad Usman, Shazma Ali, Anis Naveed, Anuda Bibi, Haseena Noor","doi":"10.1016/j.jlumin.2026.121788","DOIUrl":"10.1016/j.jlumin.2026.121788","url":null,"abstract":"<div><div>In this work, a wedge-shaped p-AlGaN layer (WPL) with bidirectional Al composition grading is introduced to overcome the limitations of conventional rectangular p-type AlGaN layer (CPL). The graded Al composition reduces the Mg acceptor activation energy, allowing a greater fraction of Mg dopants to ionize and thereby improving hole transport. Numerical simulations demonstrate that the proposed design increases the hole and electron concentrations in the active region by 7% and 4%, respectively, leading to a more uniform carrier distribution within the quantum wells. As a result, the radiative recombination rate is increased by 23%, and the internal quantum efficiency (IQE) is enhanced from 52% to 80.4%. These results highlight compositionally graded, wedge-shaped p-AlGaN layers as an effective design strategy for realizing high-performance AlGaN-based DUV LEDs.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"293 ","pages":"Article 121788"},"PeriodicalIF":3.6,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Zero-dimensional (0D) halides with the general formula A2BX6 (such as Cs2HfI6) have emerged as a promising class of next-generation scintillator materials characterized by their high luminescence efficiency. This study investigated the novel 0D halide Li2HfI6, where A-site Li+ substitution induces a structural transition to a rhombohedral structure. Comprehensive experimental and density functional theory (DFT) analyses reveal that Li+ substitution facilitates carrier delocalization. Temperature-dependent photoluminescence identified a shallow 17 meV de-trapping barrier from the self-trapped exciton (STE) to the free exciton (FE) state. This thermally induced transition, paralleling phenomena well-observed in 2D perovskites, results in a coexistence of high-energy FE and low-energy STE emissions at room temperature. The emergence of the FE component enables a rapid scintillation decay time of less than 100 ns. In addition, Li2HfI6 achieves a high thermal neutron light yield of 17,000 photons/neutron, which is approximately three times higher than commercial 6Li-glass. These characteristics demonstrate that Li2HfI6 is a promising candidate for 3He-alternative technologies. This work establishes A-site cation engineering as an effective design principle for controlling the structure and luminescence properties of 0D halide neutron scintillators.
{"title":"Optical and electronic properties of zero-dimensional-type lithium hafnium iodide scintillator","authors":"Chihaya Fujiwara , Shunsuke Kurosawa , Akihiro Yamaji , Akira Yoshikawa , Nishiki Matsubayashi , Takushi Takata , Hiroki Tanaka","doi":"10.1016/j.jlumin.2026.121784","DOIUrl":"10.1016/j.jlumin.2026.121784","url":null,"abstract":"<div><div>Zero-dimensional (0D) halides with the general formula A<sub>2</sub>BX<sub>6</sub> (such as Cs<sub>2</sub>HfI<sub>6</sub>) have emerged as a promising class of next-generation scintillator materials characterized by their high luminescence efficiency. This study investigated the novel 0D halide Li<sub>2</sub>HfI<sub>6</sub>, where A-site Li<sup>+</sup> substitution induces a structural transition to a rhombohedral structure. Comprehensive experimental and density functional theory (DFT) analyses reveal that Li<sup>+</sup> substitution facilitates carrier delocalization. Temperature-dependent photoluminescence identified a shallow 17 meV de-trapping barrier from the self-trapped exciton (STE) to the free exciton (FE) state. This thermally induced transition, paralleling phenomena well-observed in 2D perovskites, results in a coexistence of high-energy FE and low-energy STE emissions at room temperature. The emergence of the FE component enables a rapid scintillation decay time of less than 100 ns. In addition, Li<sub>2</sub>HfI<sub>6</sub> achieves a high thermal neutron light yield of 17,000 photons/neutron, which is approximately three times higher than commercial <sup>6</sup>Li-glass. These characteristics demonstrate that Li<sub>2</sub>HfI<sub>6</sub> is a promising candidate for <sup>3</sup>He-alternative technologies. This work establishes A-site cation engineering as an effective design principle for controlling the structure and luminescence properties of 0D halide neutron scintillators.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"293 ","pages":"Article 121784"},"PeriodicalIF":3.6,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
A series of BaZr(PO4)2 (BZP) phosphors activated singly with Bi3+ and codoped with Bi3+/Tb3+ has been synthesized by utilizing solid state reaction synthesis. The crystal phase, morphological studies and photoluminescennt characteristics of the prepared samples were analyzed utilizing X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Photoluminescent (PL) spectroscopy and decay curves. The XRD analysis confirmed the successful incorporation of dopant ions inside host matrix. The PL studies of singly Bi3+ activated phosphors demonstarted blue emission band around 468 nm when 313 nm wavelength source of excitation is used. The transfer of energy to Tb3+ from Bi3+ in the codoped samples was confirmed from the PL spectra and the decay kinetics. The pathway responsible for transfer of energy from Bi3+ to Tb3+ was identified as dipole-dipole interactions and critical distance between Bi3+ and Tb3+ was found to be 21.85 Å. The CIE chromaticity coordinates for single doped BaZr(PO4)2:0.03 Bi3+ was obtained to be (0.157, 0.213). The temperature dependent PL studies revealed good thermal stability of phosphor with thermal activation energy (Ea) of 0.329 eV. The color tunable emissios from blue to green region were realised in codoped phosphors by varying relative doping concentrations and excitation wavelengths, which illustrates potential use of BaZr(PO4)2: Bi3+, Bi3+/Tb3+ phosphors with tunable blue green emission in field of solid-state lighting.
{"title":"Photoluminescent properties of Bi3+ doped BaZr(PO4)2 and energy transfer in Bi3+, Tb3+ codoped phosphors","authors":"Shweta Yadav , Sumandeep Kaur , A.S. Rao , Deshraj Meena","doi":"10.1016/j.jlumin.2026.121793","DOIUrl":"10.1016/j.jlumin.2026.121793","url":null,"abstract":"<div><div>A series of BaZr(PO<sub>4</sub>)<sub>2</sub> (BZP) phosphors activated singly with Bi<sup>3+</sup> and codoped with Bi<sup>3+</sup>/Tb<sup>3+</sup> has been synthesized by utilizing solid state reaction synthesis. The crystal phase, morphological studies and photoluminescennt characteristics of the prepared samples were analyzed utilizing X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Photoluminescent (PL) spectroscopy and decay curves. The XRD analysis confirmed the successful incorporation of dopant ions inside host matrix. The PL studies of singly Bi<sup>3+</sup> activated phosphors demonstarted blue emission band around 468 nm when 313 nm wavelength source of excitation is used. The transfer of energy to Tb<sup>3+</sup> from Bi<sup>3+</sup> in the codoped samples was confirmed from the PL spectra and the decay kinetics. The pathway responsible for transfer of energy from Bi<sup>3+</sup> to Tb<sup>3+</sup> was identified as dipole-dipole interactions and critical distance between Bi<sup>3+</sup> and Tb<sup>3+</sup> was found to be 21.85 Å. The CIE chromaticity coordinates for single doped BaZr(PO<sub>4</sub>)<sub>2</sub>:0.03 Bi<sup>3+</sup> was obtained to be (0.157, 0.213). The temperature dependent PL studies revealed good thermal stability of phosphor with thermal activation energy (E<sub>a</sub>) of 0.329 eV. The color tunable emissios from blue to green region were realised in codoped phosphors by varying relative doping concentrations and excitation wavelengths, which illustrates potential use of BaZr(PO<sub>4</sub>)<sub>2</sub>: Bi<sup>3+</sup>, Bi<sup>3+</sup>/Tb<sup>3+</sup> phosphors with tunable blue green emission in field of solid-state lighting.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"293 ","pages":"Article 121793"},"PeriodicalIF":3.6,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-02-03DOI: 10.1016/j.jlumin.2026.121790
Erki Enkvist , Marju Vestman , Asko Uri , Steponas Raišys , Karolis Kazlauskas
Interchromophore triplet-to-singlet Förster-type resonant energy transfer (TS-FRET) is a fascinating mechanism enabling the harvesting of energy from triplet excited states in purely organic luminophores, culminating in delayed fluorescence. This process is highly valuable for sensitive, time-gated applications, including luminescence bioassays based on protein-responsive bio-probes. In this study, we synthesized and characterized a series of tandem luminophores composed of diverse phosphorescent donors (thiophene and selenophene) and fluorescent acceptors (Tamra and Rhodamine 101), covalently linked at varying distances, to elucidate the factors governing TS-FRET efficiency. Systematic photophysical measurements, including prompt and delayed emission lifetimes and quantum yields, revealed that the donor’s intersystem crossing (ISC) rate and donor–acceptor (D–A) separation critically influence emission characteristics. Notably, in selenophene donor-based tandem luminophores, maximum delayed fluorescence (quantum yield up to 47%) occurs at a D–A distance of ∼2.6 nm, where donor’s ISC rate outcompetes the singlet–singlet FRET (SS-FRET) rate, and the TS-FRET rate surpasses the donor’s triplet decay rate. While longer linkers in the tandem luminophores enhanced triplet population by suppressing SS-FRET, excessively short linkers resulted in non-radiative quenching. We quantitatively modeled the energy transfer dynamics using a FRET formalism extended to TS-FRET, validating it experimentally and demonstrating its applicability even in complex organic systems. These insights establish clear structure-function relationships in TS-FRET luminophores, guiding the rational design of high-performance, metal-free luminescent probes with tunable, long-lifetime emission.
{"title":"Quantitative photophysics of organic long-lifetime tandem luminophores based on phosphor-sensitized delayed fluorescence","authors":"Erki Enkvist , Marju Vestman , Asko Uri , Steponas Raišys , Karolis Kazlauskas","doi":"10.1016/j.jlumin.2026.121790","DOIUrl":"10.1016/j.jlumin.2026.121790","url":null,"abstract":"<div><div>Interchromophore triplet-to-singlet Förster-type resonant energy transfer (TS-FRET) is a fascinating mechanism enabling the harvesting of energy from triplet excited states in purely organic luminophores, culminating in delayed fluorescence. This process is highly valuable for sensitive, time-gated applications, including luminescence bioassays based on protein-responsive bio-probes. In this study, we synthesized and characterized a series of tandem luminophores composed of diverse phosphorescent donors (thiophene and selenophene) and fluorescent acceptors (Tamra and Rhodamine 101), covalently linked at varying distances, to elucidate the factors governing TS-FRET efficiency. Systematic photophysical measurements, including prompt and delayed emission lifetimes and quantum yields, revealed that the donor’s intersystem crossing (ISC) rate and donor–acceptor (D–A) separation critically influence emission characteristics. Notably, in selenophene donor-based tandem luminophores, maximum delayed fluorescence (quantum yield up to 47%) occurs at a D–A distance of ∼2.6 nm, where donor’s ISC rate outcompetes the singlet–singlet FRET (SS-FRET) rate, and the TS-FRET rate surpasses the donor’s triplet decay rate. While longer linkers in the tandem luminophores enhanced triplet population by suppressing SS-FRET, excessively short linkers resulted in non-radiative quenching. We quantitatively modeled the energy transfer dynamics using a FRET formalism extended to TS-FRET, validating it experimentally and demonstrating its applicability even in complex organic systems. These insights establish clear structure-function relationships in TS-FRET luminophores, guiding the rational design of high-performance, metal-free luminescent probes with tunable, long-lifetime emission.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"293 ","pages":"Article 121790"},"PeriodicalIF":3.6,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-02-02DOI: 10.1016/j.jlumin.2026.121780
Xulin Lu , Aijun Song , Xian-Fu Zhang
The parent compound and esterified derivative of dibenzofluorescein (DBFL) have been prepared to examine the photophysical properties. The steady-state absorption spectra, fluorescence spectra, fluorescence lifetimes, and nanosecond transient absorption spectra have been measured and compared with those of DBFL. The parent compound emits bright red fluorescence efficiently with a near 2-fold higher quantum yield and significantly longer fluorescence lifetime than that of DBFL. The DBFL esterified derivative, on the other hand, shows lower emission quantum yield and shorter lifetime. Laser flash photolysis and singlet oxygen detection studies reveal that no excited triplet state is formed upon photo-excitation. Quantum chemical calculation results reveal the photophysical mechanism that leads to changes in the fluorescence properties of DBFL parent and its derived compounds.
{"title":"Dibenzofluorescein's parent compound and derivatives: A π-extended fluorescein with intense red fluorescence","authors":"Xulin Lu , Aijun Song , Xian-Fu Zhang","doi":"10.1016/j.jlumin.2026.121780","DOIUrl":"10.1016/j.jlumin.2026.121780","url":null,"abstract":"<div><div>The parent compound and esterified derivative of dibenzofluorescein (DBFL) have been prepared to examine the photophysical properties. The steady-state absorption spectra, fluorescence spectra, fluorescence lifetimes, and nanosecond transient absorption spectra have been measured and compared with those of DBFL. The parent compound emits bright red fluorescence efficiently with a near 2-fold higher quantum yield and significantly longer fluorescence lifetime than that of DBFL. The DBFL esterified derivative, on the other hand, shows lower emission quantum yield and shorter lifetime. Laser flash photolysis and singlet oxygen detection studies reveal that no excited triplet state is formed upon photo-excitation. Quantum chemical calculation results reveal the photophysical mechanism that leads to changes in the fluorescence properties of DBFL parent and its derived compounds.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"293 ","pages":"Article 121780"},"PeriodicalIF":3.6,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
The band-to-acceptor photoluminescence in a transverse magnetic field has been investigated experimentally and theoretically in GaAs/AlAs heterojunctions. The observed linear polarization of the photoluminescence is due to two contributions. The first one arises in zero magnetic field with increasing background acceptor concentration in the heterostructure. The second one is induced by the transverse magnetic field. The experimental findings are explained within a theoretical model that accounts for the quantum-dimensional axial splitting, the in-plane crystal structure anisotropy, the Zeeman splitting of electrons and holes in magnetic field, and the redistribution of carriers over the spin sublevels in the depletion region at the heterojunction.
{"title":"Intrinsic, magnetic-field-induced linear polarization of the band-to-acceptor photoluminescence from a GaAs/AlAs heterojunction","authors":"T.S. Shamirzaev , D.A. Frolov , V.N. Mantsevich , N.S. Averkiev , M.O. Petrushkov , E.A. Emelyanov , V.V. Preobrazhenskii , M.A. Putyato , B.R. Semyagin , V.A. Haisler , D.R. Yakovlev , M. Bayer","doi":"10.1016/j.jlumin.2026.121758","DOIUrl":"10.1016/j.jlumin.2026.121758","url":null,"abstract":"<div><div>The band-to-acceptor photoluminescence in a transverse magnetic field has been investigated experimentally and theoretically in GaAs/AlAs heterojunctions. The observed linear polarization of the photoluminescence is due to two contributions. The first one arises in zero magnetic field with increasing background acceptor concentration in the heterostructure. The second one is induced by the transverse magnetic field. The experimental findings are explained within a theoretical model that accounts for the quantum-dimensional axial splitting, the in-plane crystal structure anisotropy, the Zeeman splitting of electrons and holes in magnetic field, and the redistribution of carriers over the spin sublevels in the depletion region at the heterojunction.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"293 ","pages":"Article 121758"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-01-31DOI: 10.1016/j.jlumin.2026.121783
M. Isik , T. Yildirim , S. Tüzemen
We present a comprehensive structural and optical investigation of arsenic-rich GaAs crystals grown by the liquid-encapsulated Czochralski (LEC) method. Energy-dispersive X-ray spectroscopy confirms an As-enriched stoichiometry (Ga/As ≈ 0.73), while X-ray diffraction reveals a well-defined zinc blende phase with a strong (400) preferred orientation and a lattice constant close to that of stoichiometric GaAs, indicating good crystalline quality. Temperature-dependent photoluminescence (33–300 K) exhibits intense near-band-edge and bound-exciton emissions at 33 K (∼1.521 eV), accompanied by additional low-energy emission bands. The temperature evolution of the band gap follows the Varshni relation, yielding Eg(0) ≈ 1.52 eV. Analysis of the thermal quenching behavior of the integrated near-band-edge emission intensity using the Arrhenius model provides an activation energy of approximately 30 meV, suggesting that shallow non-radiative recombination centers dominate the deactivation process. These findings elucidate the role of excess arsenic in modifying defect-related recombination processes and radiative dynamics of GaAs and offer valuable insights for the design of defect-engineered optoelectronic and photonic devices.
本文对液体包封法生长的富砷砷化镓晶体进行了全面的结构和光学研究。能量色散x射线光谱证实了砷的富集化学计量（Ga/As≈0.73），而x射线衍射显示出明确的锌闪锌矿相，具有强（400）优先取向，晶格常数接近化学计量的砷化镓，表明晶体质量良好。温度相关的光致发光（33 - 300 K）在33 K （~ 1.521 eV）表现出强烈的近带边缘和束缚激子发射，并伴有额外的低能发射带。带隙的温度演化遵循Varshni关系，产生Eg(0)≈1.52 eV。利用Arrhenius模型分析近带边缘发射强度的热猝灭行为，得到活化能约为30 meV，表明浅层非辐射复合中心主导失活过程。这些发现阐明了过量砷在改变缺陷相关重组过程和砷化镓辐射动力学中的作用，并为缺陷工程光电和光子器件的设计提供了有价值的见解。
{"title":"As-rich GaAs crystals: Temperature-dependent photoluminescence and defect-mediated emission","authors":"M. Isik , T. Yildirim , S. Tüzemen","doi":"10.1016/j.jlumin.2026.121783","DOIUrl":"10.1016/j.jlumin.2026.121783","url":null,"abstract":"<div><div>We present a comprehensive structural and optical investigation of arsenic-rich GaAs crystals grown by the liquid-encapsulated Czochralski (LEC) method. Energy-dispersive X-ray spectroscopy confirms an As-enriched stoichiometry (Ga/As ≈ 0.73), while X-ray diffraction reveals a well-defined zinc blende phase with a strong (400) preferred orientation and a lattice constant close to that of stoichiometric GaAs, indicating good crystalline quality. Temperature-dependent photoluminescence (33–300 K) exhibits intense near-band-edge and bound-exciton emissions at 33 K (∼1.521 eV), accompanied by additional low-energy emission bands. The temperature evolution of the band gap follows the Varshni relation, yielding E<sub>g</sub>(0) ≈ 1.52 eV. Analysis of the thermal quenching behavior of the integrated near-band-edge emission intensity using the Arrhenius model provides an activation energy of approximately 30 meV, suggesting that shallow non-radiative recombination centers dominate the deactivation process. These findings elucidate the role of excess arsenic in modifying defect-related recombination processes and radiative dynamics of GaAs and offer valuable insights for the design of defect-engineered optoelectronic and photonic devices.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"293 ","pages":"Article 121783"},"PeriodicalIF":3.6,"publicationDate":"2026-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
We have demonstrated a room temperature near-infrared electroluminescence (EL) at a wavelength of λ = 1.65 μm from Si/CaF2 quantum cascade laser structure. Five periods of the active layer were epitaxially grown on an n-Si (111) layer of a silicon-on-insulator (SOI) substrate, forming a single-mode propagation waveguide in transverse magnetic (TM) mode grown by molecular beam epitaxy (MBE). The active layer structure consists of a 5-monolayer (ML) transition layer quantum well, double-injector-barrier and a 4-ML blocking layer. EL spectra exhibiting multiple peaks in the near-infrared region were obtained at room temperature, and the dependence of EL intensity on the injection current clearly confirmed that the emission originated from carrier injection. Moreover, a peak shift toward longer wavelengths was observed with increasing applied voltage, and preliminary estimates confirm that the magnitude of the shift is consistent with an interpretation based on the Stark effect, strongly suggesting that the emission originates from inter subband transition of intended design.
{"title":"Electroluminescence of 1.65 μm near-infrared wavelength quantum cascade lasers using Si/CaF2 heterostructures","authors":"Zhiyuan Fan, Haibo Wang, Hyuma Suzuki, Masahiro Watanabe","doi":"10.1016/j.jlumin.2026.121786","DOIUrl":"10.1016/j.jlumin.2026.121786","url":null,"abstract":"<div><div>We have demonstrated a room temperature near-infrared electroluminescence (EL) at a wavelength of λ = 1.65 μm from Si/CaF<sub>2</sub> quantum cascade laser structure. Five periods of the active layer were epitaxially grown on an n-Si (111) layer of a silicon-on-insulator (SOI) substrate, forming a single-mode propagation waveguide in transverse magnetic (TM) mode grown by molecular beam epitaxy (MBE). The active layer structure consists of a 5-monolayer (ML) transition layer quantum well, double-injector-barrier and a 4-ML blocking layer. EL spectra exhibiting multiple peaks in the near-infrared region were obtained at room temperature, and the dependence of EL intensity on the injection current clearly confirmed that the emission originated from carrier injection. Moreover, a peak shift toward longer wavelengths was observed with increasing applied voltage, and preliminary estimates confirm that the magnitude of the shift is consistent with an interpretation based on the Stark effect, strongly suggesting that the emission originates from inter subband transition of intended design.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"293 ","pages":"Article 121786"},"PeriodicalIF":3.6,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Carbon dots doped with oxygen- and nitrogen-containing functional groups were synthesized to act as photosensitizers for singlet oxygen generation. Structural studies revealed the presence of O,N-containing functional centers on the surface of carbon dots. The absorption and luminescence properties were investigated in water-ethanol mixtures. The effects of external heavy atoms and temperature on the delayed fluorescence of the carbon dots were examined. It was found that increasing the carbon dot concentration leads to an increase in phosphorescence intensity, while the lifetime of carbon dots decreases. Upon the addition of molecules to a degassed solution of carbon dots, a singlet-triplet annihilation occurs, the efficiency of which is governed by the concentration ratio of triplet state of carbon dots to molecules. The quantum yield of generation is equal to ΦΔ = 0.29.
{"title":"Photosensitization of singlet oxygen by O,N-doped carbon dots","authors":"Niaz Ibrayev , Gulnur Amanzholova , Boris Minaev , Takhmina Khamza","doi":"10.1016/j.jlumin.2026.121781","DOIUrl":"10.1016/j.jlumin.2026.121781","url":null,"abstract":"<div><div>Carbon dots doped with oxygen- and nitrogen-containing functional groups were synthesized to act as photosensitizers for singlet oxygen <span><math><mrow><msub><mi>Ο</mi><mn>2</mn></msub><mrow><mo>(</mo><mmultiscripts><msub><mo>Δ</mo><mi>g</mi></msub><mprescripts></mprescripts><none></none><mn>1</mn></mmultiscripts><mo>)</mo></mrow></mrow></math></span> generation. Structural studies revealed the presence of O,N<strong>-</strong>containing functional centers on the surface of carbon dots. The absorption and luminescence properties were investigated in water-ethanol mixtures. The effects of external heavy atoms and temperature on the delayed fluorescence of the carbon dots were examined. It was found that increasing the carbon dot concentration leads to an increase in <span><math><mrow><msub><mi>Ο</mi><mn>2</mn></msub><mrow><mo>(</mo><mmultiscripts><msub><mo>Δ</mo><mi>g</mi></msub><mprescripts></mprescripts><none></none><mn>1</mn></mmultiscripts><mo>)</mo></mrow></mrow></math></span> phosphorescence intensity, while the lifetime of carbon dots decreases. Upon the addition of <span><math><mrow><msub><mi>Ο</mi><mn>2</mn></msub><mrow><mo>(</mo><mmultiscripts><msubsup><mi>Σ</mi><mi>g</mi><mo>−</mo></msubsup><mprescripts></mprescripts><none></none><mn>3</mn></mmultiscripts><mo>)</mo></mrow></mrow></math></span> molecules to a degassed solution of carbon dots, a singlet-triplet annihilation occurs, the efficiency of which is governed by the concentration ratio of triplet state of carbon dots to <span><math><mrow><msub><mi>Ο</mi><mn>2</mn></msub><mrow><mo>(</mo><mmultiscripts><msub><mo>Δ</mo><mi>g</mi></msub><mprescripts></mprescripts><none></none><mn>1</mn></mmultiscripts><mo>)</mo></mrow></mrow></math></span> molecules. The quantum yield of <span><math><mrow><msub><mi>Ο</mi><mn>2</mn></msub><mrow><mo>(</mo><mmultiscripts><msub><mo>Δ</mo><mi>g</mi></msub><mprescripts></mprescripts><none></none><mn>1</mn></mmultiscripts><mo>)</mo></mrow></mrow></math></span> generation is equal to Φ<sub>Δ</sub> = 0.29.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"293 ","pages":"Article 121781"},"PeriodicalIF":3.6,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146090273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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