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Reversible PL Tuning by Defect Passivation via Laser Irradiation on Aged Monolayer MoS2
摘要： Atomically thin (1L) MoS2 emerged as a direct band gap semiconductor with potential optical applications. The photoluminescence (PL) of 1L-MoS2 degrades due to aging related defect formation. The passivation of these defects leads to substantial improvement in optical properties. Here we report the enhancement of PL on aged 1L-MoS2 by laser treatment. Using photoluminescence and Raman spectroscopy in a controlled gas environment, we show the enhancement is associated with efficient adsorption of oxygen on existing sulfur vacancies preceded by removal of adsorbates from the sample’s surface. Oxygen adsorption depletes negative charges, resulting in suppression of trions and improved neutral exciton recombination. The result is a 6-8 fold increase in PL emission. The laser treatment in this work does not cause any measurable damage to the sample as verified by Raman spectroscopy, which is important for practical applications. Surprisingly, the observed PL enhancement is reversible by both vacuum and ultrafast femtosecond excitation. While the former approach allows switching a designed micro pattern on the sample ON and OFF, the latte provides a controllable mean for accurate PL tuning, which is highly desirable for optoelectronic and gas sensing applications.
关键词： Raman,Exciton,Laser Annealing,Oxygen,Photoluminescence,Reversible Defect passivation,MoS2
更新于2025-09-11 14:15:04
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Systematic Comparison of Thermal Annealing and Laser Treatment of TiO2 Thin Films Prepared by Sol-Gel Processing
摘要： Thin films with titania composition were prepared on glass substrates by dip-coating from coating solutions based on soluble precursor powders. The as-dried deposits were thermally annealed in a furnace and irradiated by a CO2 laser, respectively. Oven temperature can systematically be correlated to laser power density in terms of film thickness and refractive index. Results indicate that the formation of anatase and rutile critically depends on the different treatment conditions. Some specific microstructural features that originate from the laser irradiation are highlighted.
关键词： Laser annealing,Sol-gel processing,Thermal curing,Thin films,TiO2
更新于2025-09-11 14:15:04
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Pulsed laser annealing for advanced technology nodes: modeling and calibration
摘要： Pulsed laser annealing is one of the promising low thermal budget approaches to overcome process limitations and develop alternative schemes to achieve better device performance and enable 3D architectures. Its applications range from the Front End Of the Line (doping, contacts, strain engineering) to Back End Of the Line (Cu grain engineering) in logic and memory devices. One key enabler for integrating this disruptive technology in the coming highly challenging technology nodes is an accurate time-resolved modeling of laser matter interaction, thermal diffusion, phase change and species diffusion at the nanosecond timescale, all to be solved self-consistently. In this paper, we will present the TCAD simulation package of the laser annealing process (LASSE Innovation Application Booster or LIAB), with a specific focus on the phase field model and calibration of relevant materials. The coupled partial differential equation system is described and a methodology for materials calibration, especially challenging in the melting regime, is detailed with results shown for Ge and SiGe, with a application on a typical p-type finFET contact region anneal 2D use case.
关键词： Germanium,Laser annealing,Material modification,TCAD model calibration,Silicon-Germanium,Self-consistent models
更新于2025-09-11 14:15:04
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Ultrafast laser-annealing of perovskite films for efficient perovskite solar cells
摘要： Perovskite solar cells have attracted much attention recently for their high efficiency, ease of preparation and low cost. Here, we report a novel laser-annealing method for perovskite films at a low substrate temperature by scanning laser spots on the film surfaces. An ultrafast crystallization process within a few seconds is realized under a laser with a high intensity and a fast scanning speed. Because the crystalline perovskite phase has a stronger light absorption than the amorphous phase, the fast laser annealing can induce a higher temperature in the former and lead to the selective growth of large perovskite grains. Under optimum conditions, perovskite films with high crystallinity are successfully fabricated, resulting in perovskite solar cells with high power conversion efficiency and good stability. Moreover, a faster laser-annealing process of perovskite films is achieved by using a linear laser beam, which is expected to be a promising technique for the mass production of large-scale perovskite solar cells.
关键词： Perovskite solar cells,ultrafast crystallization,laser-annealing,large-scale production,power conversion efficiency
更新于2025-09-11 14:15:04
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A differential Hall effect measurement method with sub-nanometre resolution for active dopant concentration profiling in ultrathin doped Si <sub/>1?</sub><i> <sub/>x</sub></i> Ge <i> <sub/>x</sub></i> and Si layers
摘要： In this paper, we present an enhanced differential Hall effect measurement method (DHE) for ultrathin Si and SiGe layers for the investigation of dopant activation in the surface region with sub-nanometre resolution. In the case of SiGe, which constitutes the most challenging process, we show the reliability of the SC1 chemical solution (NH4OH/H2O2/H2O) with its slow etch rate, stoichiometry conservation and low roughness generation. The reliability of a complete DHE procedure, with an etching step as small as 0.5 nm, is demonstrated on a dedicated 20 nm thick SiGe test structure fabricated by CVD and uniformly doped in situ during growth. The developed method is finally applied to the investigation of dopant activation achieved by advanced annealing methods (including millisecond and nanosecond laser annealing) in two material systems: 6 nm thick SiGeOI and 11 nm thick SOI. In both cases, DHE is shown to be a uniquely sensitive characterisation technique for a detailed investigation of dopant activation in ultra-shallow layers, providing sub-nanometre resolution for both dopant concentration and carrier mobility depth profiles.
关键词： contact resistance,sub-nanometre resolution,fully depleted silicon on insulator (FDSOI),carrier mobility,differential Hall effect,dopant activation,laser annealing
更新于2025-09-10 09:29:36
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Raising the Operating Temperature of (Ga,Mn)As/GaAs Spin Light Emitting Diodes by Applying Post-Growth Treatment
摘要： Spin light emitting diodes (spin-LEDs) containing (Ga,Mn)As ferromagnetic layers are fabricated based on InGaAs/GaAs heterostructures and studied. We achieve increases in the operating temperatures of our spin-LEDs by subjecting the surface of the structures, prior to depositing an ohmic metal contact, to pulsed laser annealing. The fabricated devices produce circularly polarized electroluminescence when placed in an external magnetic field. The temperatures at which circularly polarized electroluminescence is still observed is raised from 30 K for unprocessed structure to 110 K for laser-annealed structures. The observed effect is linked to an increase in the Curie temperature of the (Ga,Mn)As layer as a result of laser impact.
关键词： ferromagnetic layers,circularly polarized electroluminescence,Curie temperature,Mn)As,pulsed laser annealing,Spin light emitting diodes,(Ga
更新于2025-09-10 09:29:36
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Boosting Ge-Epi P-Well Mobility & Crystal Quality with Si or Sn Implantation and Melt Annealing
摘要： We investigated the effects of Si, Sn and cluster-C implantation into both P-well and N-well doped regions of Ge-epi on Si wafers after laser annealing. XRD analysis shows improved Ge-epi crystallinity after >1.5J/cm2 laser melt annealing (liquid phase epitaxial regrowth) compared to sub-melt annealing (solid phase epitaxial regrowth). For the P-well case the Ge-epi Rs decreased to 1,600?/□ compared to Si at 3,400?/□ suggesting a hole mobility increase of 2.1x from 150cm2/V-s to 315cm2/V-s but actual measured Hall mobility was 650cm2/V-s to a depth of 60nm, an increase of 4.3x. The 1.8J/cm2 laser melt anneal with Si implant improved mobility uniformly to 700cm2/V-s to a depth of 100nm while Sn implant improved mobility to 900cm2/V-s from the Ge-epi surface to a depth of 70nm then increases to 3000cm2/V-s at a depth of 100nm. Measuring mobility depth profiles can be very critical in engineering surface and bulk mobility improvements which can be determined by chemical compositional changes in the Ge-epilayer especially for C where no liquid phase diffusion or movement could be detected.
关键词： P-well,Ge-epi,mobility,cluster-C,N-well,Si,Sn,laser annealing
更新于2025-09-09 09:28:46