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Rapidly self-heating shape memory polyurethane nanocomposite with boron-doped single-walled carbon nanotubes using near-infrared laser
摘要： In this study, boron-doped single-walled carbon nanotubes (SWCNTs) were synthesized by high-temperature heat treatment (1300 °C) with a boric acid precursor and SWCNTs instead of the conventional chemical doping process. Then, these boron-doped single-walled carbon nanotubes (B-SWCNTs) were added to polyurethane to prepare polyurethane nanocomposites having excellent thermal and mechanical properties. Changes in properties that occurred due to structural changes inside the composite were investigated as the added amount of nanofiller was increased. In particular, a near-infrared (NIR) laser (808 nm) was directly irradiated on the nanocomposite film to induce photothermal properties on the surface of the B-SWCNTs. In the case of the PU nanocomposite film with a filler content of 3 wt%, a self-heating film material that rapidly heated to 250 °C within 10 s was developed. The newly developed material can be applied to electronic devices and products as a heat-generating coating material, de-icing of airplane, a heat sink, for bio-sensing, etc., using a moulding process.
关键词： boron-doping,photothermal,thermoelectrics,carbon nanotube,polyurethane
更新于2025-11-25 10:30:42
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Optical and Microstructural Investigation of Heavy B-Doping Effects in Sublimation-Grown 3C-SiC
摘要： In this work, a complementary microstructural and optical approach is used to define processing conditions favorable for the formation of deep boron-related acceptor centers that may provide a pathway for achieving an intermediate band behavior in highly B-doped 3C-SiC. The crystallinity, boron solubility and precipitation mechanisms in sublimation-grown 3C-SiC crystals implanted to 1-3 at.% B concentrations were investigated by STEM. The revealed defect formation and boron precipitation trends upon thermal treatment in the range 1100-2000oC have been cross-correlated with the optical characterization results provided by imaging PL spectroscopy. We discuss optical activity of the implanted B ions in terms of both shallow acceptors and deep D-centers, a complex formed by a boron atom and a carbon vacancy, and associate the observed spectral developments upon annealing with the strong temperature dependence of the D-center formation efficiency, which is further enhanced by the presence of implantation-induced defects.
关键词： photoluminescence,defects,3C-SiC,STEM,implantation,boron doping
更新于2025-09-23 15:22:29
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Time-resolved photoluminescence spectral analysis of phonon-assisted DAP and e-A recombination in N+B-doped <i>n</i> -type 4H-SiC epilayers
摘要： It is crucial to clarify the roles of phonon-assisted donor-acceptor pairs (DAPs) and free-to-acceptor (e-A) emissions in n-type 4H-SiC doped with nitrogen (N) and boron (B), where N and B induce the shallow donor and the D center (deep B) acceptor levels, respectively, in order to understand the complicated carrier recombination mechanism, as well as developing fluorescent SiC with a high color rendering index by controlling the ratio of the two overlapped emissions. Here, time-resolved photoluminescence (TRPL) spectral analyses were performed, in which phonon-assisted DAPs and e-A components were individually recognized. The D center-related green luminescence (1.6–2.8 eV) shows a non-exponential decay followed by a very slow decay in TRPL measurements at room temperature (RT). It emerges that most of the DAP emission intensities decay much faster than e-A emissions and contribute to what is initially fast and non-exponential decay at low temperatures, while the slow decay at RT is mainly from e-A emissions. At a much higher temperature, such as 473 K, only the e-A emission remains and the decay transforms from non-exponential to exponential behavior. High-temperature thermal quenching of e-A emissions exhibits different behaviors for samples with differing B doping concentrations. An activation energy of 0.6 eV was estimated from the Arrhenius plot of e-A emission intensity from a B-doped sample, which matches the D center level. This indicates that the hole thermal emission rate is greatly enhanced at a high temperature, which accelerates the decay of e-A emission intensity at high temperatures.
关键词： donor-acceptor pair,time-resolved photoluminescence,silicon carbide,D center,boron doping
更新于2025-09-19 17:15:36
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Highly focused femtosecond laser directed selective boron doping in single SiC nanowire device for n-p conversion
摘要： In this work, site-selective Boron (B) doping in SiC nanowires has been demonstrated by utilizing focused femtosecond (fs) laser irradiation. Raman spectra and electrical performance indicate that the localized element doping in pristine n-type SiC nanowires can convert the segment into p-type. The formation of crystalline defects and vacancies in nanowires under fs laser irradiation, along with the simultaneous dissociation of the dopant molecules, can accelerate the doping process. Single SiC nanowire p-n junction and ?eld-effect transistors with a p-type segment have been fabricated based on the pristine n-type nanowire, showing a modi?ed electrical response as a logic gate to programmed voltage signals. This laser controlled selective doping may provide an alternative for precise element doping in semiconductors at the nanoscale, which can be promising for nanoelectronic unit fabrication.
关键词： SiC nanowire,femtosecond laser,n-p conversion,nanoelectronics,boron doping
更新于2025-09-16 10:30:52
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Development of aluminum paste with/without boron content for crystalline silicon solar cells
摘要： Improvement of aluminum alloyed p?+?back surface ?elds (p?+?BSF) which is an essential requirement for achieving high ef?ciency silicon solar cells has been an important task. One of the ways to have better quality BSFs can be to introduce screen printable aluminum pastes with boron content. Two type of pastes were developed in this work and recipes were provided in detail: screen-printable aluminum paste without boron content (B-free-Al-paste), screen-printable aluminum paste with boron content (Al-B-paste). The ingredients of the pastes were optimized and basically evaluated in terms of alloying and impurity characteristics by measurement of sheet resistances, carrier lifetimes and SIMS analysis. Carrier lifetimes of the wafers processed by Al-B-paste maintained at around 300 μs relatively higher than the wafers processed by B-free-Al-paste. P-type silicon solar cells were fabricated using developed pastes and were compared with those of the cells fabricated by commercial aluminum pastes. Best ef?ciency of 17.8% was achieved with totally vacuum-less cell production process and Suns-Voc analysis were also carried out for fabricated solar cells.
关键词： silicon solar cell,boron doping,aluminum paste
更新于2025-09-16 10:30:52
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Investigation of Improvement of Electronic Properties and Ductility of RuAl2 Semiconducting Material by Boron Doping Using First-Principles Calculations
摘要： The occupation mechanism and influence of B doping on the electronic and mechanical properties of RuAl2 semiconducting compound have been investigated using first-principles calculations. Four possible B doping sites are considered. The results show that B-doped RuAl2 is thermodynamically stable. In particular, B element prefers to occupy B(4) site in comparison with other sites. Importantly, B doping improves the electronic properties of RuAl2 by shifting the Al 3p and Ru 4d states from the Fermi level (EF) to the valence band. Although B doping weakens the resistance to volume and shear deformation as well as the elastic stiffness of RuAl2, it improves the ductility due to the formation of Ru-B and Al-B bonds. Therefore, it can be concluded that B is a favorable doping element to improve the electronic properties and ductility of RuAl2 semiconducting compound.
关键词： Boron doping,RuAl2,First-principles calculations,Ductility,Electronic properties
更新于2025-09-04 15:30:14
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Influence of Boron Antisite Defects on the Electrical Properties of MBE‐Grown GaAs Nanowires
摘要： Nanowires provide a platform for the integration of heterogeneous materials in III–V systems grown on Si. BxGa1(cid:1)xAs is an interesting material for strain applications, which has not yet been studied in nanowire form. The incorporation of boron in GaAs nanowires is investigated via DC-IV measurements. In transmission electron microscopy analysis a high concentration of boron is found at the nanowire edges, indicating surface segregation during growth. Nanowires grown under boron flux are found to exhibit Ohmic contacts and low contact resistances with p-type metallizations such as Au/Zn/Au or Cr/Au. Back-gated measurements confirmed the p-type behavior of such nanowires, indicating that boron is incorporated on antisite defects where it acts as a doubly-charged acceptor. This offers a new route for the inclusion of p-doped layers in GaAs-based nanowire heterostructures and the subsequent formation of Ohmic contacts.
关键词： boron doping,B:GaAs,nanowires,molecular beam epitaxy
更新于2025-09-04 15:30:14