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Wafer-scale high-quality Ag thin film using a ZnO buffer layer for plasmonic applications
摘要： Realizing laterally continuous, ultraflat silver (Ag) single-crystal films is a significant technological challenge. Ag thin film grown on various hetero-substrates has been used in numerous applications, due to its superior electrical and optical properties. To exploit these properties without degradation and apply these films to high-precision patterning, surface plasmonics, and so on, a high-quality thin film having an ultraflat surface and few grain boundaries is needed. A zinc oxide (ZnO) buffer layer can be used to facilitate the growth of a single-crystalline Ag thin film on a sapphire (Al2O3) substrate. ZnO films deposited on Al2O3 substrates have grain boundaries; however, Ag films grown on ZnO are nearly grain-free and close to single-crystalline quality. This can be explained by the exceptionally small extended atomic distance mismatch, of ~0.08%, between Ag and Al2O3, in which the ninth Ag atom and the eighth Al atom are matched in terms of coherence and periodicity. A modified radio frequency sputtering system with a single-crystal Ag target enabled wafer-scale growth of ultraflat, grain-free Ag films. The proposed approach using a ZnO buffer provides a new method for fabricating Ag films with high adhesion, anti-oxidative stability, and superior optical properties, and allows for easy nano-patterning.
关键词： Surface plasmon,Reflectivity,Ag thin film,EADM,ZnO buffer layer
更新于2025-09-23 15:19:57
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Impact of Hydrogen flow rate on physical properties of ZnS thin films: As potential buffer layer in solar cells
摘要： The exceptional need of potential Cd-free buffer layer in thin film solar cell devices motivated us to study the role of post-deposition Hydrogen annealing for the optimization of physical properties of ZnS thin films. The deposited films of thickness 200 nm were hydrogenated within the flow rate range of 50.0–150.0 sccm at 200°C. XRD analysis revealed transformation of amorphous into cubic phase with maximum crystallinity at 150.0 sccm for films deposited on glass substrate while into wurtzite structure for films on ITO substrate with enhanced crystallinity. A mixed phase (cubic and hexagonal) at 150.0 sccm also appeared. Electrical behaviour (I–V) exhibits ohmic nature with maximum carrier concentration at 100.0 sccm. The blue shift in absorption edge and maximum of 95% transmittance were recorded in the visible region with optical energy band gap of 3.41 eV at 150.0 sccm. The reduction in surface roughness is observed in surface topographical analysis while the photoluminescence (PL) study indicated a sharp peak at 2.95 eV with strongest emission for 150.0 sccm attributed to reduction of defects at interstitial sites and passivation of grain boundaries. These results are useful to understand the Hydrogen related impurities in ZnS films and the improvement caused by hydrogenation to physical properties suited for buffer layer in solar cells.
关键词： Buffer layer,ZnS thin films,Hydrogenation,Physical properties,e-beam evaporation
更新于2025-09-23 15:19:57
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Influence of the GaAs crystals diffusion in the shift towards low energies in the photoluminescence emission band of the GaN/GaNbuffer/GaAs structure
摘要： GaN buffer layers were obtained by nitridation of GaAs substrates and GaN upper layers were growth by MOCVD to make the GaN/GaNbuffer/GaAs structure. It was observed GaAs crystals diffusion in GaN upper layer from buffer layer, when the growth temperature reach 900 °C. Photoluminescence spectrum showed the decrease in the maximum energy from 3.2 eV (381 nm) to 2.9 eV (414 nm) with contributions in 2.6 eV (462 nm) and 2.5 eV (487 nm) related to GaAs crystals diffused in GaN upper layer and hydrogen impurities respectively, which induce extended defects in the lattice. It is considered that the temperature and the growth method of GaN buffer layer, influences the photoluminescence emission of the GaN upper layer, shifting its maximum energy to low energies. X-ray diffraction patterns and transmission electron microscopy micrographs support the presence of GaAs in the GaN upper layer of the GaN/GaNbuffer/GaAs structure obtained at 900 °C. The decrease of GaAs crystal diffusion in the GaN upper layer is observed, when its growth temperature increases from 900 to 1000 °C, with a maximum energy of 3.2 eV (381 nm).
关键词： MOCVD,Buffer layer,Diffusion,Nitridation
更新于2025-09-19 17:15:36
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Enhanced efficiency and stability of planar perovskite solar cells by introducing amino acid to SnO2/perovskite interface
摘要： Many recent studies have shown that perovskite solar cells (PSCs) employing SnO2 as an electron transport layer (ETL) exhibit extremely high efficiency which is close to that of the device with the same structure using TiO2. Considering the sensitivity of the PSC performance to the ETL/perovskite interface, interface engineering of the SnO2 electron transport layer helps to further release the potential of planar structure PSCs and promote their commercialization. Herein, we introduce an amino acid self-assembled layer onto the SnO2 ETL as the buffer layer to modulate the SnO2/perovskite lattice mismatch induced interface stress, and enhanced the interface interaction between SnO2 and perovskite caused by hydrogen-bonding and/or electrostatic interactions between the amino groups and the perovskites framework. Due to the improved perovskite film quality and enhanced interface charge transfer/extraction, a champion efficiency of 20.68% (Jsc ? 24.15 mA/cm2, Voc ? 1.10 V, and FF ? 0.78) is obtained for Cs0.05MAyFA0.95-yPbI3-xClx planar PSCs.
关键词： Perovskite solar cells,SnO2,Interface engineering,Glycine buffer layer,Self-assembly
更新于2025-09-19 17:13:59
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Sputtered ZnSnO buffer layers for kesterite solar cells
摘要： Replacing the CdS buffer layer with a ZnSnO one in Cu2ZnSnS4-based solar cells allows both to improve the device performances and to avoid using toxic Cd. Additionally, using a sputtered buffer layer is a major asset for solar cells fabricated by physical vapor deposition processes. In this study, ZnSnO layers are deposited by sputtering of a single metal-oxide target. Structural and optical properties of the layers deposited on Si or glass are first described. The possibility of modifying the ZnSnO metallic composition by adjusting the deposition power is demonstrated. Attempts to improve the optoelectronic properties of the ZnSnO layers with Ar:O2 or Ar:SF6 reactive sputtering are shown as well. These ZnSnO buffer layers are transferred in Mo/CZTS/ZnSnO/ZnO:Al solar cells. After post-deposition thermal treatment and optimization of the deposition condition (notably with the use of Ar:O2 or Ar:SF6 reactive sputtering), a solar cells with a power conversion efficiency of 5.2% is demonstrated. It is 0.6% absolute higher than the reference solar cell with a CdS buffer layer. To avoid absorber damaging and achieve high performances, deposition power must be as low as possible. A two stages sputtering process is used to conciliate both the absorber surface preservation and a reasonable deposition time. Last, photovoltaic properties of optimized CZTS- and CZTSe-based solar cells with ZnSnO buffer layers are compared.
关键词： Cu2ZnSnS4,ZnSnO buffer layer,Cd-free devices,sputtering,reactive sputtering,Kesterite solar cells
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
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Performance of Graphenea??CdS Hybrid Nanocomposite Thin Film for Applications in Cu(In,Ga)Se2 Solar Cell and H2 Production
摘要： A graphene–cadmium sulfide (Gr–CdS) nanocomposite was prepared by a chemical solution method, and its material properties were characterized by several analysis techniques. The synthesized pure CdS nanoparticles (NPs) and Gr–CdS nanocomposites were confirmed to have a stoichiometric atomic ratio (Cd/S = 1:1). The Cd 3d and S 2p peaks of the Gr–CdS nanocomposite appeared at lower binding energies compared to those of the pure CdS NPs according to X‐ray photoelectron spectroscopy analyses. The formation of the Gr–CdS nanocomposite was also evidenced by the structural analysis using Raman spectroscopy and X‐ray diffraction. Transmission electron microscopy confirmed that CdS NPs were uniformly distributed on the graphene sheets. The absorption spectra of both the Gr–CdS nanocomposite and pure CdS NPs thin films showed an absorption edge at 550 nm related to the energy band gap of CdS (~2.42 eV). The Cu(In,Ga)Se2 thin film photovoltaic device with Gr–CdS nanocomposite buffer layer showed a higher electrical conversion efficiency than that with pure CdS NPs thin film buffer layer. In addition, the water splitting efficiency of the Gr–CdS nanocomposite was almost three times higher than that of pure CdS NPs.
关键词： cadmium sulfide,Gr–CdS,Cu(In, Ga)Se2,buffer layer,water splitting
更新于2025-09-19 17:13:59
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Improved ferroelectric response of pulsed laser deposited BiFeO <sub/>3</sub> -PbTiO <sub/>3</sub> thin films around morphotropic phase boundary with interfacial PbTiO <sub/>3</sub> buffer layer
摘要： (1 ? x)BiFeO3-xPbTiO3 (BF-xPT) is an interesting material for sensing and actuating devices with large polarization near the morphotropic phase boundary (MPB) (x = 0.30) in the bulk form. However, pulsed laser deposition (PLD) grown (BF-xPT) thin films usually show high electrical leakage and, hence, saturated ferroelectric hysteresis loops are only obtained at subzero temperatures. In this article, we report on high room temperature ferroelectric polarization with saturated hysteresis loops in pulsed laser deposited (BF-xPT) polycrystalline thin films of compositions near the MPB with the use of a thin buffer layer of PbTiO3 (PT). The thin films possessed a perovskite structure with excellent crystallinity and exhibit the presence of a monoclinic (Cm) phase (MA-type) for x = 0.20–0.25 and a mixture of a monoclinic (Cm) phase and a tetragonal (P4mm) phase for x = 0.30–0.35 compositions. The thin films with composition x = 0.25 exhibit a monoclinic phase and yield very large room temperature ferroelectric polarization (2Pr > 80μC/cm2), perhaps the highest room temperature ferroelectric polarization and excellent piezoelectric properties in PLD deposited (BF-xPT) thin films of near-MPB composition. Furthermore, the evolution of ferroelectricity with PT content, studied using room temperature Raman spectroscopy, reveals a correlation with lattice dynamics and stereochemical activity of Bi. Piezoforce domain analysis of the thin films reveals that ferroelectric polarization and electrical leakage in the thin films are intricately related to the type of domains present in the samples, viz., 180°, 109°, 90°, and 71° due to differences in the nature of the domain walls.
关键词： thin films,pulsed laser deposition,PbTiO3 buffer layer,ferroelectric response,BiFeO3-PbTiO3,morphotropic phase boundary
更新于2025-09-19 17:13:59
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Stability enhancement of inverted perovskite solar cells using LiF in electron transport layer
摘要： Stability is of great importance to the commercialization of perovskite solar cells (PVSCs). Interface materials are crucial to achieve stable PVSCs. Herein, we report on a strategy of incorporating lithium fluoride (LiF) as part of the buffer layer in inverted PVSCs to suppress the decomposition of perovskite layer and eliminate the corresponding negative effects. The device with C60/LiF buffer layer maintains 87% of its initial efficiency after aging in N2 for 26 days, exhibiting much improved stability compared to the control device with C60/BCP. Our work suggests a viable approach to enhance the device stability for the commercialization of PVSCs.
关键词： Perovskite solar cells,Electron transport layer,Lithium fluoride,Buffer layer,Stability
更新于2025-09-16 10:30:52
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Theoretical investigation on enhancement of output performance of CZTSSe based solar cell
摘要： CZTSSe offers cheap, environmental friendly and earth abundant material for solar devices, yet the record power conversion efficiency for such solar cells has stagnated at about 12 percent over the years. The main reason for low output voltage and overall performance is because of the extreme non radiative recombination in the heterojunction region. To find the overall optimization of solar cell and suitable buffer layer numerical simulation has been performed by SCAPS-1D software. Here, CZTSSe was used as a absorber layer, Al doped ZnO as a transparent conducting layer and ZnO as a window layer. CdS, Cd0.4Zn0.6S and ZnSe was used as a different buffer layer. The impact of thickness of absorber layer and buffer layer on Voc, Jsc, FF and efficiency has been investigated. Also, the effect of temperature on the above-mentioned parameter of the solar cell was studied.
关键词： Heterojunction,Buffer layer,Efficiency,CZTSSe,Solar devices,Absorber layer
更新于2025-09-16 10:30:52