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Low temperature fabrication of high quality gate insulator in metal-oxide-semiconductor capacitor using laser annealing
摘要： This paper reports the fabrication of a high quality gate oxide for metal-oxide-semiconductor field effect transistors using a continuous wave blue laser. A thin Zr metal layer was inserted between the dielectric and substrate to increase laser absorption and reduce the interface layer. A simulation of laser irradiation showed that metal layer insertion induces a significant increase in temperature during laser annealing compared to the dielectric without a metal layer. The laser annealed capacitor with a 1 nm-thick Zr metal layer showed superior electrical characteristics, such as high capacitance, low leakage current, low fixed charge density and low interface state density. Based on these results and the economic advantage of blue laser diodes, this technique can be a solution for low temperature processes, such as monolithic 3-dimensional integration, where low temperature processes are required.
关键词： 445 nm wavelength,Zirconium oxide,scavenging effect,laser anneal,blue,MOSCAP,continuous wave,visible laser
更新于2025-11-14 17:28:48
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Mechanism of the Laser Flash Photolysis of Rydimeric e-Tautomers of 4-N,N-Diethylaminoazobenzene in a 2-Propanol Medium
摘要： Difference transit absorption spectra (TASes) obtained via flash photolysis of isopropanol solutions of 4-N,N-diethylaminoazobenzene (DEAB) using 15 ns laser pulses at wavelengths of λex = 265 and 353 nm are analyzed. The inconsistency of constructing the mechanism of trans (t) → cis (c) photisomerization of DEAB based on the concept of this dye having a monomeric structure is shown. Based on the rydimeric concept of aminoazobenzene dyes, which include Rydberg dimers DEAB2, an adequate explanation is given of the nature of TAS signals with structures that change dramatically when in wavelength λex is altered. TAS signals of DEAB2 are compared to ultrahigh-speed (subpico- and pico-second) TAS signals of rydimers of a reference aminoazobenzene (AAB2) dye. It is established that the main difference between the structures of DEAB2 TAS signals generated by pulses with indicated wavelengths λex is due to the excitation of various rydimeric e-tautomers. In addition, a rydimeric e-tautomer that is unstable in the ground state acquires increased stability in propanol and, by absorbing radiation with λex = 353 nm, alters the structure of one of its monomers to quinoid while remaining a rydimer. It is shown that when excited with radiation pulses at λex = 265 nm, a rydimeric e-tautomer (which is more stable in the ground state) dissociates into individual monomers, one of which isomerizes to form cis-DEAB molecules.
关键词： diethylaminoazobenzene rydimers,rydimer photonics,laser flash photolysis,trans–cis isomerization,visible laser spectroscopy
更新于2025-09-23 15:21:01
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High-Resolution Laser-Induced Graphene. Flexible Electronics Beyond the Visible Limit.
摘要： Laser-induced graphene (LIG) is a multifunctional graphene foam that is commonly direct-written with an infrared laser into a carbon-based precursor material. Here, a visible 405 nm laser is used to directly convert polyimide into LIG. This enabled the formation of LIG with a spatial resolution of ~ 12 μm and a thickness of < 5 μm. The spatial resolution enabled by the relatively smaller focused spot size of the 405 nm laser represents a > 60% reduction in LIG feature sizes reported in prior publications. This process occurs in situ in an SEM chamber, thus allowing direct observation of LIG formation. The reduced size of the LIG features enables the direct-write formation of flexible electronics which are not visible to the unaided eye. A humidity sensor is demonstrated which could detect human breath with a response time of 250 ms. With the growing interest in LIG for flexible electronics and sensors, finer features can greatly expand its utility.
关键词： high resolution,visible laser,flexible sensor,Laser-induced graphene
更新于2025-09-19 17:13:59
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Laser-based measurements and analyses on cycle-to-cycle variations of mixture formation in binary-component fuel sprays
摘要： The cyclic variations of vapor distributions of a binary-component fuel spray were experimentally investigated. Ultraviolet–visible laser absorption/scattering technique was adopted for quantitative measurement of vapor mass distributions in a binary-component fuel spray. n-Hexane and p-xylene were chosen to form the binary-component test fuel. Intersection-over-union, an important concept in object detection, was firstly introduced to characterize more precisely the spray cyclic variations, in comparison with other traditional methods including presence probability image and coefficient of variation in spray penetration. As a result, a larger fluctuation was observed in vapor distributions of the higher boiling point component (p-xylene) in the binary-component fuel compared to that of the pure p-xylene spray, indicating that evaporation characteristic of multi-component fuel spray is one of the significant factors that affects the cyclic variations. Based on large amount of experimental observations, a concept of spray vapor distribution area with consideration of cyclic variation was proposed to give a more reasonable expression of spray structure, and a new empirical formula of spray vapor distribution area was given for prediction and numerical model validation.
关键词： spray vapor distribution area,binary-component fuel spray,intersection-over-union,cyclic variations,ultraviolet–visible laser absorption/scattering
更新于2025-09-19 17:13:59
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Directly blue diode-pumped green self-Q-switched $\text{Ho}^{3+}$-doped fluoride all-fiber laser at ~550nm
摘要： We successfully demonstrate a blue diode-pumped green single-wavelength self-Q-switched Ho3+:ZrF4-BaF2-LaF3-AlF3-NaF (Ho:ZBLAN) all-fiber laser emitting at ~550 nm. Such a green laser, being a very simple device, consists of a 15-cm-long Ho:ZBLAN fiber and a pair of fiber input/output mirrors. The Ho:ZBLAN fiber not only acts as a gain medium but also works as a saturable absorber (SA). The modulation mechanism is induced by the ground-state reabsorption effect in an ineffectively pumped section of the active fiber. Stable Q-switching pulses are characterized by a 889 ns of minimum pulse duration and a 264 nJ of maximum energy pulse at a repetition rate of 67.25 kHz. We believe that this work could provide an appreciable alternative for next generation of pulsed green laser source, which finds the applications in the medical diagnosis, optical imaging, and industrial manufacturing.
关键词： Ho-doped fiber,blue-diode pumping,Optical Fiber lasers,Q-switching,visible laser
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Diode-Pumped Visible Laser Operation of Tb <sup>3+</sup> :LiLuF <sub/>4</sub>
摘要： Trivalent terbium-doped materials have been attracting the attention of the scientific community due to the capacity of Tb3+ to emit in the visible range. Efficient laser operation at green and yellow wavelengths has been demonstrated previously while laser operation in the orange and red ranges is not expected due to detrimental excited state absorption (ESA) processes [1-4]. Previous research on laser operation of Tb3+ doped materials was performed under pumping with frequency doubled optically pumped semiconductor laser (2ω-OPSL). These blue emitting pump sources exhibit an excellent beam quality at output powers up to 5 W, but they are complex, bulky, and expensive, and thus not well suited for power scaling. Diode-pumping presents a cost-efficient alternative with potential for power scaling and miniaturization. The availability of InGaN-based blue laser diodes makes it possible to match the peak absorption wavelength of the 7F6→5D4 transition of Tb3+ ions around 488 nm. Here, we present to the best of our knowledge, the first diode-pumped Tb3+ based laser. Under 200 mW of pump power at 488.3 nm, the laser operates in continuous wave (cw) at 542 or 544 nm with a maximum slope efficiency of 53% and up to 44 mW of output power.
关键词： visible laser,diode-pumped,Tb3+:LiLuF4,terbium-doped materials
更新于2025-09-11 14:15:04