- 标题
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- 实验方案
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Cu2ZnGe(S1-xSe x)4 – The challenge to synthesize single phase material
摘要： The variation of the band gap energy in Cu2ZnGeSe4 and Cu2ZnGeS4 from 1.4 eV to 1.7 eV, which is controlled by different S/(S+Se) ratios renders the Cu2ZnGe(S1-xSex)4 solid solution an interesting material for the application in multi-junction solar cells. Nevertheless, this system has a certain complexity due to the existence of different polymorphs. Cu2ZnGeSe4 crystallizes in the tetragonal kesterite type structure, whereas Cu2ZnGeS4 may crystallize in the tetragonal stannite or the orthorhombic wurtz-stannite type structure, respectively. To gain deeper insights into this complex system a systematic study of the solid solution series Cu2ZnGe(S1-xSex)4 was performed using polycrystalline material prepared by solid state reaction. The chemical analysis performed by wavelength dispersive X-ray spectroscopy showed remarkable inhomogeneities with different quaternary phases co-existing within one sample. Additionally, a wide variety of binary and ternary secondary phases as well as elemental Ge was observed. The variety of secondary phases is higher in S-rich samples than in Se-rich samples of the solid solution. Thus, synthesis of Cu2ZnGe(S1-xSex)4 mixed crystals with off-stoichiometric composition is readily accompanied by the formation of various secondary phases making it a difficult task to obtain single phase material.
关键词： Wavelength dispersive X-ray spectroscopy,Solid state reaction,Polycrystalline powders,Chalcogenides,Secondary phases,Copper zinc germanium selenide,Copper zinc germanium sulfide
更新于2025-09-11 14:15:04
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High-performance p-channel thin-film transistors with lightly doped n-type excimer-laser-crystallized germanium films
摘要： High-performance polycrystalline-germanium (poly-Ge) thin-film transistors (TFTs) fabricated with lightly doped Ge thin films by excimer laser crystallization (ELC) and counter doping (CD) have been demonstrated. High-quality n-type Ge thin films with a grain size as large as 1 μm were fabricated by ELC in the super lateral-growth regime and CD at a dose of 1 × 1013 cm?2 or higher. Consequently, a superior field-effect mobility of 271 cm2 V?1 s?1 and a high on/off current ratio of 2.7 × 103 have been obtained for p-channel Ge TFTs with the channel width and length of both 0.5 μm fabricated by ELC at 300 mJ/cm2 and CD at a dose of 1 × 1013 cm?2. The effects of ELC conditions and CD dose on the electrical characteristics of p-channel Ge TFTs were also investigated.
关键词： field-effect mobility,excimer laser crystallization,thin-film transistors,polycrystalline-germanium,counter doping
更新于2025-09-11 14:15:04
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Development of Germanium-Based Wafer-Bonded Four-Junction Solar Cells
摘要： Multijunction solar cells with four junctions are expected to be the next-generation technology for both space and concentrator photovoltaic applications. Most commercial triple-junction solar cells are today grown on germanium, which also forms the bottom subcell. Extending this concept to four junctions with an additional ～1-eV subcell was proven to be challenging. We investigate a new cell concept, which uses direct wafer bonding to combine a metamorphic GaInAs/Ge bottom tandem solar cell with a GaInP/AlGaAs top tandem on GaAs resulting in a monolithic four-junction cell on germanium. This article summarizes results of the cell developments, which have been resulting in a four-junction concentrator cell with 42% ef?ciency. We implemented a new passivated Ge backside technology to enhance the current generation in the Ge junction, and we propose realistic steps to realize solar cells with 45% ef?ciency using this cell architecture.
关键词： photovoltaics,concentrator,photovoltaic cells,germanium,III-V semiconductor materials
更新于2025-09-11 14:15:04
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High coherence at f and 2f of mid-infrared supercontinuum generation in silicon germanium waveguides
摘要： Absorption-spectroscopy based on supercontinuum generation in the mid-infrared is a powerful technique to analyze the chemical composition of samples. Furthermore, phase-coherent fast data acquisition with coherent, stable pulses that allow single-shot measurements. We report here a numerical study of the coherence of an octave-spanning mid-infrared supercontinuum source that was experimentally obtained in an air clad SiGe/Si waveguide. We show that engineering two closely spaced zero-dispersion wavelengths that enclose an anomalous dispersion band centered around a fixed pump wavelength can produce supercontinuum pulses with high spectral density and full coherence at the extreme ends of the spectrum. This work is important for absorption spectroscopy, on-chip optical frequency metrology and ??-to-2?? interferometry applications.
关键词： Optical waveguides,Silicon photonics,Silicon germanium,Supercontinuum generation
更新于2025-09-11 14:15:04
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A 26-Gb/s 3-D-Integrated Silicon Photonic Receiver in BiCMOS-55 nm and PIC25G With ?15.2-dBm OMA Sensitivity
摘要： This letter presents a 3-D-integrated 26 Gb/s opto-electrical receiver front-end. The electronic integrated circuit (EIC) is fabricated in a BiCMOS-55-nm technology, ?ipped and placed on top of the photonic integrated circuits (PICs) die through copper pillars. In the receiver chain, a fully differential shunt-feedback TI ampli?er (FD-SF TIA) is followed by a limiting ampli?ers (LAs) with embedded equalization, output driver and an automatic offset cancelation loop. The whole receiver provides a transimpedance (TI) gain of 76 dB(cid:2) with 30-GHz bandwidth. By exploiting the FD-SF TIA with low parasitic capacitance of the Germanium dual heterojunction photo diode (Ge-PD) in the photonic die, the receiver achieves sensitivity of ?15.2 dBm optical modulation amplitude (OMA) at Ge-PD and ?10-dBm OMA at the single-mode ?12 and PRBS 15. ?ber (SMF) optical output with bit error rate of 10 The sensitivity is aligned with state-of-the-art receivers employing discrete photonics and, to author’s best knowledge, it is the lowest reported among published 25 Gb/s receivers exploiting silicon photonics.
关键词： Germanium dual heterojunction photo diode (Ge-PD),3-D-integrated,transimpedance ampli?er (TIA),limiting ampli?er (LA),opto-electrical receiver
更新于2025-09-11 14:15:04
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Energy penetrated and inverse bremsstrahlung absorption co-efficient in laser ablated germanium plasma
摘要： In the present experimental conditions, at Nd:YAG laser in fundamental (1064) nm, at laser irradiance 1.0 × 1011 Wcm-2 the (IB) absorption αib is approximately equal to (0.0204 cm-1.). In present work irradiance is varied from 1.0×1011 to 1.8×1011Wcm-2 and inverse bremsstrahlung varies from 2.0×10-3 to 1.2×10-2 cm-1. The power absorbed by germanium target surface is found to be Pabs= 2.07×108 Wcm-2 and 1.04×103 Wcm-2 is reflected back from germanium surface. Whereas at highest laser irradiance 1.8×1011 Wcm-2 the power absorbed by surface is found to be Pabs= 3.67×108 Wcm-2 and 1.84×103Wcm-2 is reflected back from germanium surface. In present work we have calculated laser absorbance and percentage which is estimated by absorbed light throughout the original irradiance I0 at target surface, in present work absorbance at germanium surface is 0.2 where as reflectivity R of germanium sample which is found to be 0.39 for 1064 nm wavelength. At irradiance I0 1.0×1011 Wcm-2 the energy penetrated is E~5.05×1010 Wcm-2 and for high laser irradiance at I0 1.8×1011 Wcm-2 the energy penetrated is E~8.95×1010 Wcm-2 respectively.
关键词： plasma,Spectroscopy,germanium,LIBS,laser
更新于2025-09-11 14:15:04
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Analysis of Optical Integration between Si3N4 Waveguide and a Ge-Based Optical Modulator Using a Lateral Amorphous GeSi Taper at the Telecommunication Wavelength of 1.55 μm
摘要： We report on the theoretical investigation of using an amorphous Ge0.83Si0.17 lateral taper to enable a low-loss small-footprint optical coupling between a Si3N4 waveguide and a low-voltage Ge-based Franz–Keldysh optical modulator on a bulk Si substrate using 3D Finite-Difference Time-Domain (3D-FDTD) simulation at the optical wavelength of 1550 nm. Despite a large refractive index and optical mode size mismatch between Si3N4 and the Ge-based modulator, the coupling structure rendered a good coupling performance within fabrication tolerance of advanced complementary metal-oxide semiconductor (CMOS) processes. For integrated optical modulator performance, the Si3N4-waveguide-integrated Ge-based on Si optical modulators could simultaneously provide workable values of extinction ratio (ER) and insertion loss (IL) for optical interconnect applications with a compact footprint.
关键词： Franz–Keldysh effect,germanium,optical interconnect,silicon nitride
更新于2025-09-11 14:15:04
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Analysis of 1?MeV electron irradiation-induced performance degradation in the germanium bottom cell of triple-junction solar cells using temperature-dependent photoluminescence measurements
摘要： Temperature-dependent photoluminescence spectra of the germanium bottom cell of triple-junction solar cells unirradiated and irradiated with 1 MeV electrons were measured in the 10–300 K temperature range. In unirradiated germanium bottom cell, the spectra show that the PL intensity increases with temperature but slightly decreases at around 250 K because of the intrinsic defect. However, in irradiated germanium bottom cell, the spectra show that there are two negative thermal quenching processes (10–90 K and 200–270 K) and two usual thermal quenching processes (90–200 K and 270–300 K) as a result of the radiation-induced defects Ec (cid:1) 0.37 eV and Ec (cid:1) 0.12 eV.
关键词： Electron irradiation,germanium bottom cell,thermal quenching,temperature-dependent photoluminescence
更新于2025-09-11 14:15:04
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[IEEE 2019 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC) - Taiyuan, China (2019.7.18-2019.7.21)] 2019 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC) - High Performance Germanium n <sup>+</sup> /p Shallow Junction for nano-Scaled n-MOSFET
摘要： In this work, we study excimer laser annealing (ELA) on phosphorus-implanted germanium with implantation energies and doses of 30 keV, 5x1015 cm-2, and 10 keV, 5x1014 cm-2, respectively. A lower specific contact resistivity of Al/n+Ge and better performance of Ge n+/p diode than that obtained by rapid thermal annealing have been fulfilled. Moreover, by a combination of low temperature pre-annealing (LTPA) and ELA, we achieved a Ge n+/p diode with a rectification ratio of about 107 and decreased phosphorus diffusion in Ge during ELA. A increased activation concentration up to 6x1019cm-3 with a high activation ratio about 85% of phosphorus have been achieved in a low ion implanted dose and energy.
关键词： low temperature pre-annealing,excimer laser annealing,germanium,shallow junction
更新于2025-09-11 14:15:04
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Design of Microdisk-Shaped Ge on Si Photodetector with Recess Structure for Refractive-Index Sensing
摘要： In this paper, we introduce a disk-shaped Ge-on-Si photodetector for refractive-index difference sensing at an operating wavelength of 1550 nm. For the implementation of a small-scale sensor, a Ge layer was formed on top of a Si layer to increase the absorption coefficient at the expense of the light-detection area. Additionally, the sensor had a ring waveguide structure along the edge of the disk formed by a recess into the inner part of the disk. This increased the interaction between the dominant optical mode traveling along the edge waveguide and the refractive index of the cladding material to be sensed, and conclusively increased detection sensitivity. The simulation results show that the proposed sensor exhibited a detection sensitivity of >50 nm/RIU (Refractive Index Unit), a quality factor of approximately 3000, and a minimum detectable refractive index change of 0.95 × 10?2 RIU with a small disk radius of 3 μm. This corresponds to 1.67 times the sensitivity without a recess (>30 nm/RIU).
关键词： refractive index sensor,disk resonator,silicon on insulator,germanium photodetector
更新于2025-09-11 14:15:04