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Composition and Strain Evolution of Undoped Si <sub/>0.8</sub> Ge <sub/>0.2</sub> Layers Submitted to UV-Nanosecond Laser Annealing
摘要： Ultraviolet Nanosecond Laser Annealing (UV-NLA, XeCl laser, 308 nm, 145 ns) was performed on 30 nm-thick Si0.8Ge0.2 epitaxial layers. The various regimes encountered after single pulse UV-NLA are described and discussed, including submelt, SiGe layer partial and total melt, as well as melt beyond the SiGe epi-layer. Energy densities around 2.00 J/cm2 and above led to the formation of pseudomorphic layers with strong Ge redistribution. Starting from uniform Si0.8Ge0.2 layers, Ge segregation towards the surface resulted in the formation of a Ge-rich surface layer with up to 55% Ge for 2.00 J/cm2. Such pseudomorphic SiGe layers with graded composition and a Ge-rich surface layer may find some promising applications such as contact resistance lowering in doped layers.
关键词： SiGe,pseudomorphic,contact resistance,Ge redistribution,Ultraviolet Nanosecond Laser Annealing
更新于2025-11-14 14:32:36
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Reduced Graphene Oxide-Nanostructured Silicon Photosensors With High Photoresponsivity at Room Temperature
摘要： We have created nanostructured Si (~3 nm) with a direct band gap of 1.37 eV on electrically conducting reduced graphene oxide (rGO) for a highly efficient photosensor. This robust photosensor is fabricated using a non-equilibrium processing route, where nanosecond excimer laser pulses melt the alternating layers of Si and amorphous carbon to form micropillars and nanoreceptors of Si on rGO layers. The incident white light generates free carriers in the Si microstructures and nanoreceptors which are ballistically transported (via rGO layers) to the external circuit under the application of a voltage bias. The responsivity of rGO-Si devices to light (resistance vs time) and I-V measurements indicate an exponential drop in resistance with the incidence of white light and non-rectifying nature, respectively. Photoresponsivity of the rGO-Si devices is calculated to be 3.55 A/W at room temperature, which is significantly larger than the previously fabricated graphene-based Ohmic photosensors. Temperature-dependent resistance measurements of rGO-Si structures follow Efros-Shklovoskii variable range hopping (ES-VRH) electrical conduction in the low-temperature region (<100 K) and Arrhenius conduction in the high-temperature region (>100 K). In rGO, the localization length, hopping energy, and activation energy are calculated to be 17.58 μm, 3.15 meV, and 1.67 meV, respectively. The 2D nature of highly reduced and less defective rGO also render an interesting negative magnetoresistance (~2.5 %) at 5 K, thereby indicating potential implications of rGO-Si in opto-spintronics. The large-area integration of rGO-Si structures with sapphire employing nanosecond pulsed laser annealing and its exciting photosensing properties will open a new frontier for further extensive research in these functionalized 2D materials.
关键词： Pulsed laser annealing,Raman spectroscopy,Variable range hopping,Nanostructures,Reduced graphene oxide
更新于2025-09-23 15:22:29
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Near Infrared Lasera??Annealed IZO Flexible Device as a Sensitive H2S Sensor at Room Temperature
摘要： A metal-oxide material (indium zinc oxide [IZO]) device with near-infrared (NIR) laser annealing was demonstrated on both glass and bendable plastic substrates (polycarbonate, polyethylene, and polyethylene terephthalate). After only 60 s, the sheet resistance of IZO films annealed with a laser was comparable to that of thermal-annealed devices at temperatures in the range of 200°C–300°C (1 hr). XPS, ATR, and AFM were used to investigate the changes in the sheet resistance and correlate them to the composition and morphology of the thin film. Finally, the NIR laser-annealed IZO films were demonstrated to be capable of detecting changes in humidity and serving as a highly sensitive gas sensor of hydrogen sulfide (in parts-per-billion concentration), with room-temperature operation on a bendable substrate.
关键词： IZO,sol-gel,laser annealing,NIR,gas sensor,flexible
更新于2025-09-23 15:21:01
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On the Formation of Amorphous Ge Nanoclusters and Ge Nanocrystals in GeSixOy Films on Quartz Substrates by Furnace and Pulsed Laser Annealing
摘要： Nonstoichiometric GeO0.5[SiO2]0.5 and GeO0.5[SiO]0.5 germanosilicate glassy films are produced by the high-vacuum coevaporation of GeO2 and either SiO or SiO2 powders with deposition onto a cold fused silica substrate. Then the films are subjected to furnace or laser annealing (a XeCl laser, λ = 308 nm, pulse duration of 15 ns). The properties of the samples are studied by transmittance and reflectance spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy. As shown by analysis of the Raman spectra, the GeO[SiO] film deposited at a substrate temperature of 100°C contains amorphous Ge clusters, whereas no signal from Ge–Ge bond vibrations is observed in the Raman spectra of the GeO[SiO2] film deposited at the same temperature. The optical absorption edge of the as-deposited GeO[SiO2] film corresponds to ~400 nm; at the same time, in the GeO[SiO] film, absorption is observed right up to the near-infrared region, which is apparently due to absorption in Ge clusters. Annealing induces a shift of the absorption edge to longer wavelengths. After annealing of the GeO[SiO2] film at 450°C, amorphous germanium clusters are detected in the film, and after annealing at 550°C as well as after pulsed laser annealing, germanium nanocrystals are detected. The crystallization of amorphous Ge nanoclusters in the GeO[SiO] film requires annealing at a temperature of 680°C. In this case, the size of Ge nanoclusters in this film are smaller than that in the GeO[SiO2] film. It is not possible to crystallize Ge clusters in the GeO[SiO] film. It seems obvious that the smaller the semiconductor nanoclusters in an insulating matrix, the more difficult it is to crystallize them. In the low-temperature photoluminescence spectra of the annealed films, signals caused by either defects or Ge clusters are detected.
关键词： crystallization,pulsed laser annealing,germanosilicate glasses,germanium nanoclusters
更新于2025-09-23 15:21:01
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Dopant Activation of In Situ Phosphorusa??Doped Silicon Using Multia??Pulse Nanosecond Laser Annealing
摘要： Nanosecond laser annealing was performed on ISPD silicon in single- and multi-pulse modes. the active phosphorus concentration was increased with the laser power density and number of laser pulses and more phosphorus was activated with nanosecond lasers than with millisecond lasers. Moreover, almost all the incorporated phosphorus atoms were activated by the nanosecond laser without major strain loss when ISPD silicon melt
关键词： phosphorus-doped silicon,nanosecond laser annealing,diffusion,dopant activation,strain
更新于2025-09-23 15:19:57
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Study on laser annealing of niobium films deposited on copper for RF superconducting cavities
摘要： Niobium sputtered copper cavities were proposed as a kind of promising next generation superconducting cavities, but were still challenged by the Q-slope effect under high acceleration gradients. Current solutions focus on improving the film quality to make it more bulk-like, for which a higher substrate temperature is required. However, due to the limitation of the melting point of the copper substrate, both the deposition process and the post-annealing process cannot be performed at a high temperature. The laser annealing mentioned in this paper uses nanosecond pulsed laser as the heat source, and the local temperature field generated within the thickness scale of the niobium film can anneal the film without affecting copper substrate. Laser annealing system has been set up in Peking University, and experiments with niobium thin film on copper (Nb/Cu) samples have been carried out. Superconducting performance, surface topography and other properties of Nb/Cu samples before and after annealing are compared. Recrystallization of niobium films happened and various factors that may cause Q-slope have been suppressed according to the results. All these indicate the effectiveness of laser annealing and the possibility of being used in niobium sputtered copper cavities in the future.
关键词： Surface topography,Surface roughness,Recrystallization,Niobium thin film,Superconducting cavity,Laser annealing
更新于2025-09-23 15:19:57
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Effects of different annealing processes on optoelectronic and bending fatigue properties of AgZr and ITO/AgZr thin film metallic glass
摘要： Transparent conducting oxide (TCO) films are widely used throughout the optoelectronics industry. The present study explores the optoelectronic responses of AgZr (AZ) and ITO/AgZr (IAZ) thin film metallic glasses (TFMGs) with different Ag and Zr compositions and processed by two different annealing methods, namely furnace annealing (FA) and laser annealing (LA). Among the various as-deposited AZ and IAZ films, the ITO/Ag66Zr34 (IA6Z) film has the highest optical transmittance (55.7%) and the lowest sheet resistance (145.8 Ω/□). For the FA samples, an annealing temperature of 300 °C results in the optimal optoelectronic properties, namely a transmittance of 68.4% and a sheet resistance of 47.2 Ω/□. For the LA samples, the optimal processing conditions (a pulse energy of 2.5 μJ and a repetition rate of 150 kHz) yield optical transmittance and sheet resistance values of 64.0% and 17.8 Ω/□ respectively. The optimal LA processing conditions increase the Haacke figure of merit of the IA6Z sample from 2.0 × 10?5 under the as-deposited condition to 6.5 × 10?4 Ω?1 under the annealed condition; corresponding to a 32.5-fold improvement. Finally, the relative change in resistivity (ΔR/R0, where R0 is the initial resistivity, Ri is the measured resistivity after a certain number of cycles, and ΔR is Ri - R0) of the as-deposited IA6Z sample following fatigue testing (10,000 cycles) with a bend radius of 7 mm (ΔR/R0 = 0.49) is significantly lower than that of a pure ITO film of roughly equivalent thickness (ΔR/R0 = 0.93).
关键词： Laser annealing,Bi-layered electrode,Furnace annealing,Thin film metallic glass
更新于2025-09-19 17:15:36
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Spinel structured LiMn <sub/>2</sub> O <sub/>4</sub> prepared by laser annealing
摘要： Laser annealing is used for preparation of LiMn2O4. The electrochemical characterisation shows that the cycle performance of spinel LiMn2O4 is dependent on the power of the laser and the amount of lithium excess. X-ray di?raction is used to study the phase evolution of laser-annealed LiMn2O4. The morphology of LiMn2O4 particles is observed by scanning electron microscope. Electrochemical tests show that the initial capacity of the laser- annealed LiMn2O4 is less than the untreated LiMn2O4, but the cycle performance improved noticeably.
关键词： cathode,Laser annealing,LiMn2O4,spinel
更新于2025-09-19 17:13:59
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Laser Annealing of P and Al Implanted 4H-SiC Epitaxial Layers
摘要： This work describes the development of a new method for ion implantation induced crystal damage recovery using multiple XeCl (308 nm) laser pulses with a duration of 30 ns. Experimental activity was carried on single phosphorus (P) as well as double phosphorus and aluminum (Al) implanted 4H-SiC epitaxial layers. Samples were then characterized through micro-Raman spectroscopy, Photoluminescence (PL) and Transmission Electron Microscopy (TEM) and results were compared with those coming from P implanted thermally annealed samples at 1650–1700–1750 °C for 30 min. The activity outcome shows that laser annealing allows to achieve full crystal recovery in the energy density range between 0.50 and 0.60 J/cm2. Moreover, laser treated crystal shows an almost stress-free lattice with respect to thermally annealed samples that are characterized by high point and extended defects concentration. Laser annealing process, instead, allows to strongly reduce carbon vacancy (VC) concentration in the implanted area and to avoid intra-bandgap carrier recombination centres. Implanted area was almost preserved, except for some surface oxidation processes due to oxygen leakage inside the testing chamber. However, the results of this experimental activity gives way to laser annealing process viability for damage recovery and dopant activation inside the implanted area.
关键词： ion implantation,phosphorus,point defects,laser annealing,photoluminescence,aluminum,TEM,Metal Oxide Semiconductor Field Effect Transistor (MOSFET),SiC,Raman
更新于2025-09-19 17:13:59
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Excimer laser annealing method for achieving low electrical resistivity and high work function in transparent conductive amorphous In2O3:Zn films on a polyethylene terephthalate substrate
摘要： We have developed an excimer laser annealing method to achieve low electrical resistivity (ρ) and a high work function in amorphous In2O3:Zn (IZO) films on polyethylene terephthalate (PET) substrates. The effect of excimer laser irradiation of the films on crack formation, electrical properties (ρ, carrier concentration, and Hall mobility), and work function were investigated. KrF excimer laser irradiation produced cracks in the surface of the IZO films on PET as a result of thermal expansion of the PET substrate. By inserting an amorphous SiO2 layer as a heat barrier between the IZO layer and PET substrate, crack formation was prevented. Moreover, it was found that the work function of IZO film could be controlled by the laser fluence and repetition rate. Irradiation of a 150-nm-thick amorphous IZO film on a SiO2-coated PET substrate achieved a low ρ of 3.55 × 10?4 Ω cm and a high work function of 5.4 eV due to the reduction of oxygen and carbon while maintaining a flat surface.
关键词： Excimer laser annealing,Work function control,Buffer layer,Transparent conducting oxide
更新于2025-09-19 17:13:59