2025
Two-photon and three-photon excitation in GaN by spectrally broadband and few-cycle laser pulses
Wang M, Xiao J, Wang M, Yi J, Song Y, Zhang Y, Wang J, Cao B, Lienau C, Xu K. Two-photon and three-photon excitation in GaN by spectrally broadband and few-cycle laser pulses. Optics & Laser Technology 2025, 191: 113334. DOI: 10.1016/j.optlastec.2025.113334.Peer-Reviewed Original ResearchThree-photon excitationTwo-photonGaN near band edge emissionsFew-cycle laser pulsesFew-cycle pulsesSimultaneous two-photonSpatial intensity fluctuationsMultiple nonlinear processesFew-cycleLaser pulsesBroadband pulsesNear-band-edge emissionFrequency conversionIntensity fluctuationsElectronic signal processingUltrashort laserPetahertzNonlinear interactionsNonlinear signalsExcitationGaNNonlinear processesSurface morphologyFilm qualityPulseLuminescence properties of homoepitaxial Mg-doped GaN under different doping concentrations and annealing atmospheres
Wu W, Shu Z, Wang X, Wang Y, Pan Y, Sun J, Gao X, Zheng S, Wang M, Zeng X, Xu K. Luminescence properties of homoepitaxial Mg-doped GaN under different doping concentrations and annealing atmospheres. Journal Of Luminescence 2025, 284: 121294. DOI: 10.1016/j.jlumin.2025.121294.Peer-Reviewed Original ResearchLuminescence propertiesDoping concentrationP-type GaN thin filmMg-doped GaNGaN thin filmsMg dopingRoom temperature PLAcceptor energy levelCm-3Defect statesEnergy levelsMgGa acceptorN2 annealingO2 annealingCL spectraMg doping concentrationAnnealing atmosphereFS substrateThin filmsLuminescenceDopingGaN.Low temperaturesAnnealingAcceptorMicrostructure and thermal conductance of the AlN-on-sapphire heterostructure prepared by metal-organic chemical vapor deposition
Wang L, Zhou J, Su X, Chen J, Li Z, Zhu J, Zhang Z, Chang G, Xia S, Yin T, Niu M, Tang D, Xu K. Microstructure and thermal conductance of the AlN-on-sapphire heterostructure prepared by metal-organic chemical vapor deposition. Vacuum 2025, 238: 114335. DOI: 10.1016/j.vacuum.2025.114335.Peer-Reviewed Original ResearchAlN-on-sapphireThickness of AlN filmMetal organic chemical vapor depositionAlN filmsChemical vapor depositionAlN/sapphire interfaceThermal conductivityVapor depositionIncrease of tensile stressTime-domain thermoreflectance techniqueAlN film thicknessAlGaN-based ultraviolet light-emitting diodesAlGaN-based UV LEDsChemically bonded interfaceInterfacial thermal conductanceHeat transfer abilityHeat transfer mechanismPhonon densityUltraviolet light-emitting diodesUV LEDsMicrostructure of AlNAlN thicknessAlN/sapphireLarger lattice mismatchLattice mismatchTa-based Au-free and low annealing temperature ohmic contacts on GaN and AlGaN/GaN heterostructures
Xia S, Zhang Y, Sun Y, Zhu Q, Liu W, Wang J, Xu K. Ta-based Au-free and low annealing temperature ohmic contacts on GaN and AlGaN/GaN heterostructures. Materials Letters 2025, 391: 138473. DOI: 10.1016/j.matlet.2025.138473.Peer-Reviewed Original ResearchMitochondrial DNA Haplogroups, Biomarkers of Inflammation and Immune Activation, and Risk of Diabetes in Veterans With and Without Human Immunodeficiency Virus
Yan A, Kundu S, Samuels D, Bailin S, Xu K, So-Armah K, Butt A, Gerschenson M, Goetz M, Doyle M, Tracy R, Marconi V, Justice A, Freiberg M, Koethe J, Hulgan T. Mitochondrial DNA Haplogroups, Biomarkers of Inflammation and Immune Activation, and Risk of Diabetes in Veterans With and Without Human Immunodeficiency Virus. The Journal Of Infectious Diseases 2025, jiaf304. PMID: 40488298, DOI: 10.1093/infdis/jiaf304.Peer-Reviewed Original ResearchHaplogroup L3MtDNA haplogroupsCD4+ T cellsAssociated with incident DMVeterans Aging Cohort StudyBlack PWHT cellsMitochondrial DNA haplogroupsIncident DMHaplogroupsWomen of African ancestryVeterans Aging Cohort Study participantsHaplogroup associationsT-cell phenotypeHuman immunodeficiency virusType 2 diabetes mellitusSerum IL-6Associated with DMBiomarkers of inflammationCellular immune biomarkersAging Cohort StudyRisk of diabetesDM outcomesGenome-wide genotypingCD28-negativeGrowth behavior and optical properties of V-pits in GaN grown by a Na flux method
Zhang T, Liu Z, Si Z, Peng X, Dong X, Li M, Tang N, Xu K. Growth behavior and optical properties of V-pits in GaN grown by a Na flux method. CrystEngComm 2025, 27: 3675-3681. DOI: 10.1039/d5ce00095e.Peer-Reviewed Original ResearchHotspot and nonequilibrium thermal transport in AlGaN/GaN FinFET: A coupled electron-phonon Monte Carlo simulation study
Hu B, Wang Z, Xu K, Tang D. Hotspot and nonequilibrium thermal transport in AlGaN/GaN FinFET: A coupled electron-phonon Monte Carlo simulation study. International Journal Of Heat And Mass Transfer 2025, 241: 126679. DOI: 10.1016/j.ijheatmasstransfer.2025.126679.Peer-Reviewed Original ResearchNonequilibrium thermal transportThermal transportAlGaN/GaN FinFETsPolar optical scatteringElectron-phonon scatteringThermal transport processesPrimary phonon modesFirst-principles calculationsSevere self-heating effectPhonon modesStrong nonequilibriumEmission processMonte Carlo simulationsEnergy dissipation processIntermediate stateDissipative processesOptical scatteringSelf-heating effectCarlo simulationsTransport processesDissipation timeScatteringPeak temperature riseCoupling effectComplex transport mechanismsResearch on the epitaxial growth of Power/RF HEMT structures on n-GaN and Fe-doped SI-GaN Free-Standing Substrates by MOCVD
Wang X, Zhang Y, Wang M, Wang J, Xu K. Research on the epitaxial growth of Power/RF HEMT structures on n-GaN and Fe-doped SI-GaN Free-Standing Substrates by MOCVD. Vacuum 2025, 235: 114135. DOI: 10.1016/j.vacuum.2025.114135.Peer-Reviewed Original ResearchMetal organic chemical vapor depositionHigh-electron-mobility transistorsEpitaxial layersTwo-dimensional electron gasAlGaN/GaN high-electron-mobility transistorsEpitaxial growthLow-temperature mobilityGaN channel layerSemi-insulating GaNFree-standing GaN substratesGaN buffer layerRadio frequencyFe impurity concentrationsElectron gasChemical vapor depositionImpurity concentrationHEMT structuresEpitaxial structureDislocation densityN-GaNLow-temperature growthGaN substratesStopper layerChannel layerSurface roughnessUltralow Contact Resistivity of <0.13 Ω · mm for Normal Ti/Al/Ni/Au Ohmic Contact on Non-Recessed i-AlGaN/GaN
Wang X, Lin Z, Zhang Y, Wang J, Xu K. Ultralow Contact Resistivity of <0.13 Ω · mm for Normal Ti/Al/Ni/Au Ohmic Contact on Non-Recessed i-AlGaN/GaN. IEEE Transactions On Electron Devices 2025, 72: 2246-2251. DOI: 10.1109/ted.2025.3555265.Peer-Reviewed Original ResearchA Review of the Evolution of Residual Stresses in Additive Manufacturing During Selective Laser Melting Technology
Bian P, Jammal A, Xu K, Ye F, Zhao N, Song Y. A Review of the Evolution of Residual Stresses in Additive Manufacturing During Selective Laser Melting Technology. Materials 2025, 18: 1707. PMID: 40333274, PMCID: PMC12028742, DOI: 10.3390/ma18081707.Peer-Reviewed Original ResearchResidual stressAdditive manufacturingEvolution of residual stressesSelective laser melting technologyAreas of compressive stressLaser melting technologyApplication of SLMPlane stressLaser meltingTensile stressCompressive stressMelting technologyParameter matchingThermal stressPlane directionComponent failuresDominant stressFormation mechanismTemperature gradientSurface layerSLMRoom temperatureDistribution regularityRegularities of distributionExcessive stressEffect of Laser Power on Cracking Behavior of TiC/Fe-based Cladding Coatings
Liu M, Dou W, Wei X, Niu Y, Chang G, Meng Y, Shi Y, Wang X, Zhang Z, Hu B, Ma F, Xu K. Effect of Laser Power on Cracking Behavior of TiC/Fe-based Cladding Coatings. Journal Of Physics Conference Series 2025, 2981: 012012. DOI: 10.1088/1742-6596/2981/1/012012.Peer-Reviewed Original ResearchIncrease of laser powerCladding coatingLaser powerScanning electron microscopyCrack sensitivityMelt poolHigh-speed laser cladding technologyEffects of laser powerLaser cladding technologyTiC ceramic particlesFinite element simulationsOptical microscopyHigh laser powerCladding technologyResidual stressCracking behaviorElement simulationsCeramic particlesMolten poolNondestructive testingStress fieldCrackCoatingCooling rateTemperature gradientAnalysis of breakdown characteristics of GaN-based HEMT by subdividing current components
Wang X, Lin Z, Zhang Y, Wang J, Xu K. Analysis of breakdown characteristics of GaN-based HEMT by subdividing current components. Physica Scripta 2025, 100: 045507. DOI: 10.1088/1402-4896/adb6ff.Peer-Reviewed Original ResearchPostoperative TIPS Reaction in a Patient With Portal Vein Dysfunction
Du Q, Lan J, Xu K, Niu M. Postoperative TIPS Reaction in a Patient With Portal Vein Dysfunction. Portal Hypertension & Cirrhosis 2025, 4: 134-137. DOI: 10.1002/poh2.70003.Peer-Reviewed Original ResearchEffect of AlN interlayer thickness on thermal conductances of GaN epilayer and GaN/SiC interface in GaN-on-SiC heterostructures
Wang L, Zhang Z, Su X, Zhou J, Chen J, Li Z, Chang G, Xia S, Yin T, Niu M, Zhu J, Tang D, Xu K. Effect of AlN interlayer thickness on thermal conductances of GaN epilayer and GaN/SiC interface in GaN-on-SiC heterostructures. Applied Surface Science 2025, 686: 162106. DOI: 10.1016/j.apsusc.2024.162106.Peer-Reviewed Original ResearchHigh electron mobility transistorsAlN interlayer thicknessGaN-on-SiCGaN epilayersAlN interlayerPhonon density of statesHeteroepitaxial growth of GaNDensity of statesAtomically smooth interfaceThermal conductivityElectron mobility transistorsTime-domain thermoreflectanceMultilayer structureEnhancement of G′Growth of GaNInterfacial thermal conductanceInterlayer thicknessMetal organic chemical vapor depositionSiC substrateMobility transistorsAlN bufferGrow GaNChemical vapor depositionIsland shapeGaNUnintentional Fe incorporation in the homo-epitaxy of GaN on Fe-doped freestanding GaN substrate
Xia S, Zhang Y, Sun Y, Zhu Q, Liu W, Yi J, Xue J, Wang J, Xu K. Unintentional Fe incorporation in the homo-epitaxy of GaN on Fe-doped freestanding GaN substrate. Applied Physics Express 2025, 18: 031001. DOI: 10.35848/1882-0786/adbc44.Peer-Reviewed Original ResearchGaN substratesThermal decompositionHigh-electron-mobility transistor devicesHomo-epitaxyFe incorporationFe dopingVapor phase decompositionSecondary ion mass spectroscopy measurementsFe-doped GaN substrateMeasurement resultsMolecular beam epitaxial growthTransistor devicesFe-dopingMass spectroscopy measurementsPhase decompositionHeating processSpectroscopy measurementsEpitaxial growthGaN epilayersGa-faceMemory effectGaNLow temperaturesIncorporation mechanismDopingOn the dependence of internal stress on dislocation inclination pattern in HVPE-GaN substrates
Zhou F, Li Z, Liu M, Qiu Y, Yin T, Xu Y, Zhang Y, Niu M, Cai D, Wang J, Xu K. On the dependence of internal stress on dislocation inclination pattern in HVPE-GaN substrates. Applied Physics Letters 2025, 126: 082101. DOI: 10.1063/5.0255742.Peer-Reviewed Original ResearchInternal stressX-ray topographyDislocation configurationsDislocation patternsHVPE GaN substratesInclination of threading dislocationsTwo-photon excited photoluminescenceCombined Raman spectroscopyDependence of internal stressesRaman spectroscopyX-rayExcited photoluminescenceHydride vapor phase epitaxyVapor phase epitaxyDistribution of internal stressesDislocationInternal stress distributionPerformance of GaN devicesClassical elasticity theoryEpitaxial growthPhase epitaxyGaN substratesGaN devicesStress distributionElasticity theoryInfluence of Surface Treatments on the Ohmic Contact Performance on the N-Face of Iron-Doped Semi-Insulating Freestanding GaN
Sun Y, Zhang Y, Wang X, Zhou H, Xia S, Zhu Q, Liu W, Wang J, Xu K. Influence of Surface Treatments on the Ohmic Contact Performance on the N-Face of Iron-Doped Semi-Insulating Freestanding GaN. IEEE Transactions On Electron Devices 2025, 72: 1027-1034. DOI: 10.1109/ted.2025.3534739.Peer-Reviewed Original ResearchOhmic contact performanceOhmic contactsGaN-based devicesInfluence of surface treatmentContact performanceSurface treatmentBand bendingN-faceInductively coupled plasmaSpecific contact resistanceOptimized ohmic contactsInductively coupled plasma etchingImproved surface morphologySurface band bendingLow carrier concentrationGaOx layerElectrical performanceSemi-insulatingContact resistanceSurface statesWet etchingSurface roughnessCarrier concentrationSurface morphologyDry etchingOptical properties of Mg-implanted GaN grown on free-standing substrates
Wu W, Pan Y, Gao X, Wang X, Wei S, Sun J, Zeng X, Zheng S, Xu K. Optical properties of Mg-implanted GaN grown on free-standing substrates. Journal Of Physics D 2025, 58: 135101. DOI: 10.1088/1361-6463/ada8bb.Peer-Reviewed Original ResearchGaN:MgGaN thin filmsLuminescence bandThin filmsMetal organic chemical vapor depositionGreen luminescence bandBlue luminescence bandM-plane substrateLow-temperature PL spectraAcceptor energy levelChemical vapor depositionGaN free-standing substrateMg-doped GaNMg-implanted GaNUltraviolet luminescence peakPL spectraC-plane substratesLuminescence peakOptical propertiesEnergy levelsVapor depositionIon implantationAcceptorMgGa acceptorPhotoluminescenceElectron–phonon coupling and thermal transport properties of GaN/AlGaN heterojunction under strain regulation
Chen J, Shan Z, Hu B, Wang Z, Tang D, Xu K. Electron–phonon coupling and thermal transport properties of GaN/AlGaN heterojunction under strain regulation. Physical Chemistry Chemical Physics 2025, 27: 2495-2509. PMID: 39804036, DOI: 10.1039/d4cp03880k.Peer-Reviewed Original ResearchElectron-phonon couplingIn-plane stressesTensile strainThermal transportCompressive strainPhonon frequenciesTwo-dimensional electron gasElectron-phonon coupling phenomenaSemiconductor materialsInterface thermal transportApplication of semiconductor materialsStates of phononsLow-frequency phononsFirst-principles calculationsThermoelectric properties of semiconductor materialsThermal transport propertiesBallistic phonon transportInterference of strainNon-equilibrium stateProperties of semiconductor materialsMigration of electronsThermal transport mechanismsIn-plane strainElectron gasPhonon modesP-531. Mitochondrial DNA Haplogroups and Circulating Immune Cell Phenotypes in Veterans with and without HIV
Yan A, Kundu S, Samuels D, Bailin S, Xu K, So-Armah K, Butt A, Gerschenson M, Goetz M, Tracy R, Marconi V, Justice A, Freiberg M, Koethe J, Hulgan T. P-531. Mitochondrial DNA Haplogroups and Circulating Immune Cell Phenotypes in Veterans with and without HIV. Open Forum Infectious Diseases 2025, 12: ofae631.730. PMCID: PMC11777815, DOI: 10.1093/ofid/ofae631.730.Peer-Reviewed Original ResearchCD8+ T cellsPeripheral blood mononuclear cellsCD4+ T cellsT cellsHIV statusEffector memory CD8+ T cellsPeripheral blood mononuclear cell phenotypeMemory CD8+ T cellsCirculating immune cell phenotypesFlow cytometryPlasma viral loadImmune response to viral infectionImmune cell phenotypesBlood mononuclear cellsCellular immune responsesInfluence cellular immune responsesWilcoxon rank sum testResponse to viral infectionSignificant univariate associationsVeterans Aging Cohort Study Biomarker CohortRank sum testBlack PWHCD28-negativeMemory CD8White PWH
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