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Highly Rectifying Heterojunctions Formed by Annealed ZnO Nanorods on GaN Substrates
摘要： We study the effect of thermal annealing on the electrical properties of the nanoscale p-n heterojunctions based on single n-type ZnO nanorods on p-type GaN substrates. The ZnO nanorods are prepared by chemical bath deposition on both plain GaN substrates and on the substrates locally patterned by focused ion beam lithography. Electrical properties of single nanorod heterojunctions are measured with a nanoprobe in the vacuum chamber of a scanning electron microscope. The focused ion beam lithography provides a uniform nucleation of ZnO, which results in a uniform growth of ZnO nanorods. The specific configuration of the interface between the ZnO nanorods and GaN substrate created by the focused ion beam suppresses the surface leakage current and improves the current-voltage characteristics. Further improvement of the electrical characteristics is achieved by annealing of the structures in nitrogen, which limits the defect-mediated leakage current and increases the carrier injection efficiency.
关键词： chemical bath deposition,nanoscale heterojunctions,ZnO nanorods,nanoprobe in the scanning electron microscope,current-voltage characteristics,annealing,focused ion beam patterning
更新于2025-09-23 15:19:57
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Plasmonic Nanoparticles in Dielectrics Synthesized by Ion Beams: Optical Properties and Photonic Applications
摘要： The zero-dimensional metallic nanoparticles (NPs) have attracted tremendous attention in various areas owing to the collective oscillation of electron gas that couples with electromagnetic field, known as localized surface plasmon resonance (LSPR). In practical applications, the tailoring of LSPR effect is of significant importance for promising photonic devices with designed nanocomposite systems and enhanced optical properties. Ion beam technology has been demonstrated to be an efficient method to fabricate NPs embedded in dielectrics for LSPR tailoring and material modification. By manipulating the parameters of ion beams, the shape, size, and structure of NPs can be well controlled, which enables the dielectrics to possess novel linear and nonlinear optical properties. In this review, the latest research progress on the ion beam synthesis of various NPs is systematically summarized. The tailoring of linear and nonlinear optical properties of dielectrics by NPs is discussed in detail. Selected applications are presented to indicate the development of the plasmonic NPs in dielectric systems for photonic applications.
关键词： localized surface plasmon resonance,ion beam modification,nonlinear optical responses,photonic applications,plasmonic nanoparticles
更新于2025-09-23 15:19:57
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Performance analysis of p-LPZO/n-GZO and p-SZO/n-GZO homojunction UV photodetectors
摘要： A comprehensive analytical model for the dark current and photoresponsivity of ZnO thin film based homojunction ultraviolet (UV) photodetector (PD) is proposed in this study. The detailed insight about the effects of different acceptor doping materials in the illuminated surface layer is presented in this work. The recombination velocity of the carriers and the effect of applied reverse bias, specifically on the responsivity of p-n homojunction based UV PD are elucidated. The impact of two different types of dual ion beam sputtering (DIBS)-grown acceptor-doped ZnO (Sb:ZnO and Li-P:ZnO) materials on the responsivity is also discussed. The investigation results reveal that an increase in applied reverse bias results in higher responsivity due to depletion region increase leading to higher charge carrier photogeneration. Further, on comparing the results with the experimentally reported ZnO-based homojunction UV PDs, it is found that, by incorporating Sb:ZnO as p-type layer, dark current and responsivity values are improved by ~38 and ~63.7%, respectively. Hence, the developed model is significant for the design optimization of high-performance ZnO thin film-based UV homojunction PDs.
关键词： Dual ion beam sputtering (DIBS),Responsivity,Photodetector (PD),Ultraviolet (UV)
更新于2025-09-23 15:19:57
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Defect Localization and Nanofabrication for Conductive Structures with Voltage Contrast in Helium Ion Microscopy
摘要： As the dimensions of feature sizes in electronic devices decrease to nanoscale, an easy method for failure analysis and evaluation of processing steps is required. Gallium focused ion beam (Ga-FIB) or scanning electron microscope (SEM) are efficient approaches to detect voltage contrast for addressing failure analysis in semiconductor devices and processing. However, Ga-FIB may cause damage or implantation to the surface of the analyzed area, and its resolution is low. Helium ion microscopy (HIM) uses a light ion beam (helium or neon) for imaging and fabrication in nanoscale. With passive voltage contrast (PVC) in HIM images, the defect localization for failure of conductive structures can be rapidly and easily detected with sufficient voltage contrast. Furthermore, a defect gap as narrow as sub 10-nm can be investigated with HIM imaging. PVC with HIM is an efficient method for defect localization at nanoscale with minimal damage to the analyzed area. For circuit edit and failure analysis, it may be necessary to intentionally cut the conductive connection. In this circumstance, final results can be easily verified using PVC imaging with HIM. With XeF2 gas assistance, both helium and neon ion beams can be used to perform nanofabrication for metal disconnection. XeF2 gas plays an important role in preventing deposition of conductive materials on etching region and enhancing material removal rates to achieve electrically isolated structures. The etching rate with a neon ion beam is much faster than that of a helium ion beam. PVC in HIM images with controllable operation and dimensions using a helium ion beam with XeF2 gas assistance could also be used to localize a hidden defect for a single-location-defect situation. With neon ion beam irradiation on a defective location, PVC can be used to find the defect locations in the case of a series of defects.
关键词： defect,voltage contrast,XeF2,focused ion beam,etching,helium ion microscopy,nanofabrication
更新于2025-09-19 17:15:36
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Silicon nanostructuring by Ag ions implantation through nanosphere lithography mask
摘要： Nanosphere lithography is an effective technique for high throughput fabrication of well-ordered patterns on large areas. This study reports on nanostructuring of silicon samples by means of Ag ions implantation through self-organized polystyrene (PS) masks. The PS nanospheres with a diameter of ～150 nm were self-assembled in a hexagonal array on top of Si(100) wafers, and then used as a mask for subsequent 60 keV silver ion implantation. Different fluences were applied up to 2 × 10^16 ions/cm^2 in order to create a distribution of different sizes and densities of buried metal nanoparticles. The surface morphology and the subsurface structures were studied by scanning electron microscopy and cross-sectional transmission electron microscopy, as a function of the mask deformation upon irradiation and the implantation parameters itself. We demonstrate that Ag is implanted into Si only through the mask openings, thus forming a regular array of amorphized regions over the wide area of silicon substrate. These fragments are of similar dimensions of the spheres with widths of about 190 nm and distributed over 60 nm in depth due to the given ion range. At the subsurface region of the implanted fragments, the synthesis of small sized and optically active Ag nanoparticles is clearly observed. The samples show a strong absorption peak in the long-wavelength region from 689 to 745 nm characteristic for surface plasmon resonance excitations, which could be fitted well using the Maxwell-Garnett`s theory.
关键词： Nanostructuring,Ag nanoparticles,SPR peak,Silicon,Polystyrene nanomask,Ion beam implantation
更新于2025-09-19 17:15:36
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Precise Potential Observation of a Biased GaAs p-n Junction by <i>in situ</i> Phase-shifting Electron Holography; é????§??°??????GaAs p-n??￥??????é???2??o|é???-??·??????-??°????????￡???????????′è|3?ˉ?;
摘要： 昨今，半導体デバイスの研究開発において，動作中の電位温度 120 K の低温下でバルク試料の一部を薄膜化することにより作製した．この試料を電圧印加用 TEM 試料ホルダーにセットし，外部電源と電気的に接続することで TEM 内試料への電圧印加を可能とした．観察はホログラフィー電子顕微鏡(HF3300EH)を用いて加速電圧 300 kV で実施した．位相シフト法による位相再生には，入射電子線の初期位相をシフトして撮影した50枚のホログラムを用いた．
关键词： pn junction,cooling focused ion beam,electron beam holography
更新于2025-09-19 17:13:59
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In-Depth Spectroscopy and New Heights for Organic Solar Cells
摘要： In this issue of Joule, Lami et al. describe a method that enables UV photoemission spectroscopy (UPS) in the transverse dimension of polymeric semiconductor layers with nanometer-scale resolution. The approach is based on the use of Argon gas cluster ion beam (GCIB) etching instead of monoatomic ion beam bombardment. The use of GCIB reduces surface damage, enabling in depth UPS. The method is applied to the study of critical electronic levels and photovoltage in organic solar cells.
关键词： Argon gas cluster ion beam,photovoltage,UV photoemission spectroscopy,electronic levels,organic solar cells
更新于2025-09-19 17:13:59
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The impact of nano-bubbles on the laser performance of hafnia films deposited by oxygen assisted ion beam sputtering method
摘要： Hafnia is a high refractive index material used in the manufacturing of dielectric coatings for next generation lasers. The formation of defects during deposition is the major barrier to realizing high laser-damage resistant coatings for future high energy density laser applications. Understanding the precursors responsible for laser-induced damage in hafnia is therefore critical. In this work, we investigate the mechanism of laser-induced damage in 90-nm thick hafnia films produced by an oxygen assisted dual ion beam sputtering (IBS) process. Under pulsed, nanosecond ultraviolet laser exposure (355 nm, 8 ns), the laser-induced damage onset is found to be strongly dependent on the amount of argon and excessive oxygen entrapped in the nanobubbles within the hafnia films. The presence of nanobubbles is revealed and confirmed by small angle X-ray scattering and scanning/transmission electron microscopy coupled with high-angle annular dark-field. The damage onset is stable initially but decreases as the energy of oxygen goes beyond 100 eV. The damage initiation is ascribed to a laser-induced plasma generation within the nanobubbles through multiphoton ionization. The results reveal that nanobubbles formed in the IBS produced coatings are a potent precursor. Although nanobubbles are commonly present in IBS films, their negative impact on laser damage resistance of hafnia films has not been previously recognized. Our findings provide a fundamental basis for the development of potential mitigation strategies required for the realization of laser damage resistant hafnia films.
关键词： laser-induced damage,multiphoton ionization,ion beam sputtering,hafnia,nanobubbles
更新于2025-09-16 10:30:52
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Modulation of the plasmonic characteristics of Ti-Zr ternary nitride thin films by assisting ions
摘要： Plasmonic Ti-Zr ternary nitride thin films, with ZrNx and TiNx thin films as controls, were prepared with bombardment of assisting ions. The effects of the energy (Ea) and current density (Ja) of assisting ions, on the structure and plasmonic properties of the Ti-Zr ternary nitride thin films were investigated. All the films are B1-structured with a mixed orientation of (1 1 1) and (2 2 0). Higher Ea leads to higher nitrogen content and reduced the titanium content. Higher Ja or Ea can reduce the plasmonic resonance frequency and reduce the energy loss. Moreover, the plasmonic quality factors of the films can also be modulated by Ea and Ja in a wide range. It is possible that the change of the conductivity mainly underly the Ion beam modification of the plasmonic characteristics. The results of this work give an effective method to tune the plasmonic performances of ternary nitride films in visible and near infrared region.
关键词： Ion beam assisted deposition,Ternary nitride,Plasmonic,(Ti,Zr)Nx
更新于2025-09-16 10:30:52
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Cryo-focused ion beam preparation of perovskite based solar cells for atom probe tomography
摘要： Focused-ion beam lift-out and annular milling is the most common method used for obtaining site specific specimens for atom probe tomography (APT) experiments and transmission electron microscopy. However, one of the main limitations of this technique comes from the structural damage as well as chemical degradation caused by the beam of high-energy ions. These aspects are especially critical in highly-sensitive specimens. In this regard, ion beam milling under cryogenic conditions has been an established technique for damage mitigation. Here, we implement a cryo-focused ion beam approach to prepare specimens for APT measurements from a quadruple cation perovskite-based solar cell device with 19.7% efficiency. As opposed to room temperature FIB milling we found that cryo-milling considerably improved APT results in terms of yield and composition measurement, i.e. halide loss, both related to less defects within the APT specimen. Based on our approach we discuss the prospects of reliable atom probe measurements of perovskite based solar cell materials. An insight into the field evaporation behavior of the organic-inorganic molecules that compose the perovskite material is also given with the aim of expanding the applicability of APT experiments towards nano-characterization of complex organo-metal materials.
关键词： field evaporation,solar cells,APT,atom probe tomography,FIB,cryo-focused ion beam,perovskite,halide loss
更新于2025-09-16 10:30:52