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Ferroelectric Enhanced Performance of a GeSn/Ge Dual-Nanowire Photodetector
摘要： GeSn offers a reduced bandgap than Ge and has been utilized in Si-based infrared photodetectors with extended cutoff wavelength. However, traditional GeSn/Ge heterostructure usually consists defects like misfit dislocations due to the lattice mismatch issue. The defects with the large feature size of photodetector fabricated on bulk GeSn/Ge heterostructure induces considerable dark current. Here, we demonstrate a flexible GeSn/Ge dual-nanowire (NW) structure, in which the strain relaxation is achieved by the elastic deformation without introducing defects and the feature dimension is naturally at nanoscale. Photodetector with low dark current can be built on GeSn/Ge dual-NW, which exhibits an extended detection wavelength beyond 2 μm and the enhanced responsivity compared to Ge NW. Moreover, the dark current can be further suppressed by the depletion effect from ferroelectric polymer side gate. Our work suggests the flexible GeSn/Ge dual-NW may open an avenue for Si-compatible optoelectronic circuits operating in the short-wavelength infrared range.
关键词： Nanowire,Germanium-tin,Molecular beam epitaxy (MBE),Side-gated,Photodetector,Ferroelectrical polymer
更新于2025-11-21 11:01:37
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Room Temperature Synthesis of Germanium Oxide Nanofilaments and Their Potential Use as Luminescent Self‐Cleaning Surfaces
摘要： Germanium oxide nanofilaments (GNFs) have been synthesized under ambient conditions from the gas phase using germanium tetrachloride as a precursor. Non-crystalline GNFs synthesized by this procedure are 1-10 μm in length and 80-110 nm in diameter applying Droplet Assisted Growth and Shaping (DAGS) Chemistry. The relative humidity has been adjusted at various values in order to demonstrate the crucial role of humidity in the gas phase for the nanofilament synthesis. The novel GNFs show a strong luminescence emission in the ultra-violet and light blue region. In addition, a self-cleaning and superhydrophobic properties could be introduced in the luminescent GNF nanofilaments by simple treatment with silane molecules.
关键词： silicone nanofilaments,chemical vapor deposition,DAGS chemistry,germanium oxide nanofilaments,self-cleaning surfaces
更新于2025-11-14 15:18:02
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Germanium catalyzed vapor–liquid–solid growth and characterization of amorphous silicon oxide nanotubes: comparison to the growth of its nanowires
摘要： One-dimensional (1D) nanostructures were grown with a simple technique using continuous-wave laser vaporization of a Ge target containing 5 at.% Si in high-pressure (up to 0.9 MPa) Ar gas atmosphere. A maximum amount (~ 30% of all products) of 1D nanostructures was obtained at 0.9 MPa and these nanostructures were identified as amorphous silicon oxide (SiOx) nanotubes (NTs) and attached with crystalline Ge-rich NPs with elongated prolate-like or sphere-like shapes at their tips by transmission electron microscopy (TEM), high-angle annular dark-field-scanning TEM, and energy dispersive X-ray line scan spectrometry. As the Ar pressure decreased from 0.9 to 0.03 MPa, the average diameters, wall thicknesses, and lengths of the NTs decreased from 57.9 to 22.9 nm, 13.2 to 6.7 nm, and 2.1 to 0.2 μm, respectively, and the tip NP size decreased from 139.0 to 41.7 nm. There was a strong correlation among the diameters, wall thicknesses, and lengths of the NTs and tip Ge NP sizes, indicating the role of molten Ge NPs as catalyst seeds for the precipitation of SiOx in a vapor–liquid–solid growth mechanism at high temperature. The SiOx precipitation quantities from the seed NPs for the NTs were compared with those of amorphous SiOx nanowires (NWs) at 0.1–0.9 MPa to clarify the growth mechanism of the NTs. We argue that smaller precipitation quantities of SiOx than those for the NWs play a critical role in the formation of cap structures with different sizes and shapes from the molten Ge NPs and the growth of the NTs.
关键词： Laser vaporization,Germanium catalyst,Silicon oxide,Nanotube,Nanowire
更新于2025-09-23 15:23:52
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Atomic Structures and Electronic Properties of Large-Sized GeN Clusters (N?=?45, 50, 55, 60, 65, 70) by First-Principles Global Search
摘要： A two-step unbiased global search was performed to explore the lowest-energy structures of large GeN clusters with N = 45–70 atoms. It has been revealed that the most stable structures for these large-sized Ge clusters are stuffed cages. Based on the lowest-energy structures, the theoretical results for the size-dependent structural transition, binding energy and ionization potential compare well with the available experimental data. Overall speaking, the structural characteristics and electronic properties of GeN clusters in the considered size range gradually approach the bulk limits, but still with certain deviations.
关键词： Global search,Germanium cluster,Structure
更新于2025-09-23 15:23:52
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Abrupt changes in the graphene on Ge(001) system at the onset of surface melting
摘要： By combining scanning probe microscopy with Raman and x-ray photoelectron spectroscopies, we investigate the evolution of CVD-grown graphene/Ge(001) as a function of the deposition temperature in close proximity to the Ge melting point, highlighting an abrupt change of the graphene’s quality, morphology, electronic properties and growth mode at 930 °C. We attribute this discontinuity to the incomplete surface melting of the Ge substrate and show how incomplete melting explains a variety of diverse and long-debated peculiar features of the graphene/Ge(001), including the characteristic nanostructuring of the Ge substrate induced by graphene overgrowth. We find that the quasi-liquid Ge layer formed close to 930 °C is fundamental to obtain high-quality graphene, while a temperature decrease of 10 degrees already results in a wrinkled and defective graphene film.
关键词： Chemical Vapor Deposition,Germanium,Scanning Tunneling Microscopy,Catalysis,Graphene
更新于2025-09-23 15:23:52
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The role of incidence angle in the morphology evolution of Ge surfaces irradiated by medium-energy Au ions
摘要： Germanium (Ge) surfaces have been irradiated with 26 keV gold (Au) ions at a constant fluence and at incidence angles varying from 0° to 85°. The evolution of the emerging nanostructures is studied by atomic force microscopy (AFM), scanning electron microscopy, x-ray photoelectron spectroscopy (XPS), and cross-sectional transmission electron microscopy. The obtained results are compared with findings reported in the literature. Periodic rippled patterns with the wave vector parallel to the projection of the ion beam direction onto the Ge surface develop between 30° and 45°. From 75° the morphology changes from parallel-mode ripples to parallel-mode terraces, and by further increasing the incidence angle the terraces coarsen and show a progressive break-up of the front facing the ion beam. No perpendicular-mode ripples or terraces have been observed. The analysis of the AFM height profiles and slope distributions shows in the 45°–85° range an angular dependence of the temporal scale for the onset of nonlinear processes. For incidence angles below 45°, the surface develops a sponge-like structure, which persists at higher incidence angles on the top and partially on the face of the facets facing the ion beam. The XPS and the energy-dispersive x-ray spectroscopy evidence the presence of Au nano-aggregates of different sizes for the different incidence angles. This study points out the peculiar behavior of Ge surfaces irradiated with medium-energy Au ions and warns about the differences to be faced when trying to build a universal framework for the description of semiconductor pattern evolution under ion-beam irradiation.
关键词： ion beam irradiation,gold ions,terraces,germanium,binary system,sponge-like structures,ripples
更新于2025-09-23 15:23:52
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Easy preparation of nanoporous Ge/Cu3Ge composite and its high performances towards lithium storage
摘要： Nanoporous Ge/Cu3Ge composite is fabricated simply through selective dealloying of GeCuAl precursor alloy in dilute alkaline solution. The as-made Ge/Cu3Ge is characterized by three dimensional (3D) bicontinuous network nanostructure which comprises of substantial nanoscale pore voids and ligaments. Owing to the 3D porous architecture and the introduction of well-conductive Cu3Ge, the lithium storage performances of Ge are dramatically enhanced in terms of higher cycling stability and superior rate performance. Nanoporous Ge/Cu3Ge anode delivers steady capacities above 1000 mA h g-1 upon cycling for 70 loops at 400 mA g-1. In particular, after 300 cycles at the high rate of 3200 mA g-1 the capacity retention for Ge/Cu3Ge is able to reach a maximum of 99.3%. On the contrary, the pure nanoporous Ge encounters severe capacity decay. In view of the outstanding energy storage performances and easy preparation, nanoporous Ge/Cu3Ge exhibits great application potential as an advanced anode in lithium storage related technologies.
关键词： dealloying,anode,lithium ion batteries,nanoporous,germanium
更新于2025-09-23 15:23:52
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2.01～ 2.42 μm all-fiber femtosecond Raman soliton generation in a heavily germanium doped fiber
摘要： We demonstrated that an all-fiber system generates high-performance mid-infrared Raman solitons in a heavily germanium doped fiber (HGDF). A 10 m-long HGDF with a 12 μm core diameter and 64 mol.% GeO2 dopant is designed and pumped by a home-made 1.96 μm femtosecond fiber laser in the strong anomalous dispersion region. Stable and single-color Raman solitons are therefore obtained with a continuous wavelength tunability from 2.01 to 2.42 μm. The pulse duration of the mid-infrared Raman solitons can be as short as ~220 fs. The efficiency of energy transfer to a Raman soliton is about 32.5%, while the maximum average power, peak power and pulse energy are up to 27 mW, 3.6 kW and ~1 nJ, respectively. Different from previous multi-color Raman or supercontinuum-like generation from HGDFs pumped in the near-zero or normal dispersion regime, such pure mid-infrared Raman solitons exhibit excellent stability with a radio-frequency signal-to-noise ratio of ~60 dB. This is, to the best of our knowledge, the first demonstration of >2.4 μm stable Raman solitons in an all-fiber system. This work may pave a path towards compact and high-performance mid-infrared femtosecond fiber laser sources.
关键词： soliton self-frequency shift,Ultrafast fiber lasers,heavily germanium doped fiber,mid-infrared
更新于2025-09-23 15:22:29
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Methods for obtaining characteristic γ-ray net peak count from interlaced overlap peak in HPGe γ-ray spectrometer system
摘要： For a characteristic c-ray with interlaced overlap peak, and the case where its reliable and credible net count cannot be obtained using the current high-purity germanium (HPGe) multichannel c-ray spectrum software, two new methods are proposed herein to obtain the c-ray net peak count from the interlaced overlap peak in the HPGe c-ray spectrometer system, of which one is the symmetric conversion method based on Gaussian distribution and the other is where the energy average value of two close c-rays is regarded as the c-ray energy. The experimental results indicate that the two methods mentioned above are reliable and credible. This study is signi?cant for the development of better c-ray spectrum processing software for measuring complex c-ray spectra concerning the nuclear reaction cross section, neutron activation analysis, and analysis of transuranium elements, using an HPGe detector.
关键词： High-purity germanium (HPGe) c-ray spectrometer system,Peak count,Interlaced overlap peak
更新于2025-09-23 15:22:29
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Mathematical modeling on non-dispersive extraction of germanium from aqueous solutions using Aliquat 336
摘要： In this work, the mathematical modeling of the facilitated transport of germanium (non-dispersive extraction) through a flat sheet membrane with an Aliquat 336 carrier was described. The flat sheet supported liquid membrane (FSSLM) experiments were performed under the condition being Ge ≈ 100 mg/L, the tartaric acid concentration of 2.76 mmol/L, and carrier concentrations of 2.5 to 10%v/v. The extraction equilibrium, mass transfer and diffusion equations based on Fick’s law were used. Modeling was carried out by programming in Matlab mathematical software to obtain the extraction (Kex) and mass transfer constants (Km) as the objective parameters. According to the model resolution, Kex and Km were found to be 0.178 and 9.25 × 10?2 cm/s, respectively. The correlation coefficients between model and experimental data relating to the Aliquat 336 concentrations of 2.5, 5, 7.5, and 10%v/v were found as 0.96, 0.98, 0.99, and 0.92. The parameters of root mean square (RMSE), bias, and scatter index (SI) showed the model accuracy. In addition, diffusion coefficients (Dm) relating to Aliquat 336 concentrations of 2.5, 5, 7.5, and 10%v/v were calculated using mass transfer coefficients to be 2.4 × 10??, 2.23 × 10??, 1.91 × 10??, and 1.79 × 10?? cm2/s, respectively.
关键词： supported liquid membrane,Aliquat 336,modeling,germanium,mass transfer
更新于2025-09-23 15:22:29