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Reliability Characterization and Modelling of High Speed Ge Photodetectors
摘要： Understanding the origin and protocols to induce performance degradations of silicon photonics high speed photodetector represent a major issue for the qualification of the reliability of these devices. Using advanced characterization technics, it is shown that the dark current, the photonic current and the cut-off frequency of the photodiode can be degraded during voltage stress of 106 s, which could ultimately induce some significant device performance drift and failure. An explanation of these degradations is presented based on both electrical observed characterization degradations of both dark current and responsivity can indeed be modeled by a single carrier lifetime degradation, attributed to an impacting an increase of the surface recombination rate, unexpected in the this model are photocurrent. The results obtained with experimentally confirmed by extracting the activation energy of the dark current, before and after stress. The improved physical understanding of the degradation is expected to lead to shorter test protocols for silicon photonics devices.
关键词： carrier lifetime electrical characterization,Silicon photonics,activation energy,Ge photodetectors reliability
更新于2025-09-11 14:15:04
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Temperature-Dependent Photoluminescence in CdTe/ZnTe Triple Quantum Dots
摘要： We studied the optical properties of CdTe/ZnTe quantum dots (QDs) in single, double, and triple QD structures by measuring the temperature-dependent photoluminescence (PL). On going from the single to the triple QD structures, the PL peak position of the QDs was blue shifted. This blue-shift was attributed to compressive strain imparted by the separation layers and to material intermixing. Temperature-dependent PL measurements of the triple QD structures showed that, as the temperature increased, the PL peak intensity for the 4.5-monolayer (ML) QDs decreased less than it did for the 3.0- and the 3.5-ML QDs. The activation energy of the 4.5-ML QDs in the triple QD structures was larger than that of the corresponding 4.5-ML QDs in the single QD structures. The reason for this is that, as the temperature increases, some carriers disappear due to non-radiative recombination, but many carriers in the 3.0- and the 3.5-ML QDs move to the 4.5-ML QDs in the triple QD structures, and those carriers then undergo radiative recombination.
关键词： Cadmium telluride,Photoluminescence,Triple quantum dots,Activation energy
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Dark Current Analysis of Vertical p-i-n Photodetectors on a Germanium-on-Insulator Platform
摘要： Dark current of vertical p-i-n photodetectors on a germanium-on-insulator platform was analyzed. The activation energy was found to be from 0.15 to 0.36 eV under reserve bias. The dark current generation was interpreted by Shockley-Read-Hall and trap-assisted-tunneling effects. This work provides the interpretation on germanium-on-insulator photodetectors and suggests the alternative to suppress the dark current generation for Si-based Ge photodetectors.
关键词： Ge-on-insulator,photodetector,activation energy,direct wafer bonding
更新于2025-09-11 14:15:04
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Phase structure and oxygen permeability of BaCe <sub/>0.15</sub> Co <sub/>x</sub> Fe <sub/>0.85?x</sub> O <sub/> 3? <i>δ</i> </sub> perovskite materials
摘要： Cerium-doped perovskite materials, BaCe0.15CoxFe0.85-xO3?δ, were synthesized by a sol-gel method. Phase structure and microstructure of BaCe0.15CoxFe0.85?xO3?δ were investigated using XRD and SEM. The critical doping value of x = 0.15 for cerium ions can be obtained for BaCe0.15CoxFe0.85?xO3?δ. This paper further investigated the effect of cobalt ions on the phase structure of BaCe0.15CoxFe0.85?xO3?δ. As the cobalt doping content is more than 0.6, BaCe0.15CoxFe0.85?xO3?δ deviates from cubic perovskite phase completely. Oxygen permeation test revealed that the oxygen permeability of BaCe0.15CoxFe0.85?xO3?δ series increases with the increase of cobalt doping. Among BaCe0.15CoxFe0.85?xO3?δ materials, BaCe0.15Co0.4Fe0.45O3?δ exhibits cubic perovskite structure and excellent oxygen permeation performance.
关键词： doping,activation energy,perovskite,x-ray diffraction,phase structure
更新于2025-09-11 14:15:04
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Structural and electrical properties of boron doped InSe single crystals
摘要： Structural and electrical properties of undoped, 0.1%, 0.5% and 1.8% boron doped InSe single crystals grown by modified Bridgman method have been studied by using XRD, Raman and I-V measurements. XRD spectra reveal that undoped and boron doped crystals investigated have hexagonal structure with lattice parameters a = 4.005 ?, c = 16.640 ? and z = 4, belonging to the P63/mmc space group. The strongest peak in the XRD patterns is due to the reflection from the (004) plane indicating that these crystals grew with a preferred orientation. Raman spectra show phonon bands in the 400-450 cm-1 wavenumber range characteristics of InSe single crystals. Temperature dependence of conductivity of undoped and boron doped InSe single crystals show three different mechanisms discerned as extended state conductivity, conduction in band tail and conduction in localized sites. It is observed that electrical conductivity increases while activation energy decreases with increasing boron concentration.
关键词： Raman,XRD,activation energy,Boron doped InSe single crystals
更新于2025-09-10 09:29:36
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Some insights into the structure and morphology of surfactant-doped poly(o-toluidine)
摘要： Poly(o- toluidine) (POT) doped with dodecylbenzene sulfonic acid (DBSA) was synthesized by inverse emulsion polymerization and characterized systematically for morphological, structural, electrochemical, and thermal properties with scanning electron microscopy (SEM), cyclic voltammetry (CV), X- ray diffraction (XRD), and thermogravimetric analysis (TGA). SEM demonstrated irregular granular morphology of the polymer with high porosity similar to polyaniline (PANI). The size distribution of POT salts was analyzed using Nano Measurer 1.2.5 software from scanning electron micrographs. The semicrystalline nature, with crystallite size and d- spacing in the range of 21.4–30.2 nm and 4.93–4.99 ?, respectively, was confirmed from XRD. The activation energy (Ea) of degradation was calculated from TGA curves using Coats and Redfern (39.92–47.50 kJ/mol) & Horwitz and Metzger (50.09 ? 57.45 kJ/mol) methods, respectively. The small crystallite size, high thermal stability, and high values of the activation energy of degradation reveal that DBSA is an efficient dopant for POT and imparts interesting characteristics to this otherwise less thermally stable polymer. The fast rate of electron transfer of POT, as confirmed by electrochemical impedance spectroscopy, reveals its high electrochemical activity toward electrolyte. Potentiodynamic polarization measurement of POT- coated stainless steel showed large anodic potential shift as compared to uncoated stainless steel, illustrated good anticorrosion performance. The enhanced anticorrosion performance is due to synergic effect of dopant which increases the contortion of diffusion pathway of corrosive substance.
关键词： thermogravimetric analysis,cyclic voltammetry,stainless steel,poly(o-toluidine)-doped with dodecylbenzene sulfonic acid,X-ray diffraction,activation energy,anticorrosion
更新于2025-09-10 09:29:36
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Study of dielectric relaxation and thermally activated a.c. conduction in multicomponent Ge10-xSe60Te30Inx (0 ≤ x ≤ 6) chalcogenide glasses using CBH model
摘要： Amorphous Ge10-xSe60Te30Inx (0 ≤ x ≤ 6) chalcogenide glasses were prepared by melt quench technique. Surface morphology with the chemical composition of the prepared glass was examined using SEM and EDS analysis respectively. Dielectric properties and a.c. conductivity of the multicomponent Ge10-xSe60Te30Inx (0 ≤ x ≤ 6) chalcogenide glasses have been examined in the frequency range 100Hz to 1MHz and temperature range 303 to 328K. It was noticed that dielectric constant and dielectric loss decreases with the increase of frequency and increases with the increase of temperatures. Frequency and temperature dependence of dielectric constant was explained by orientational polarization. The variation of dielectric loss with frequency and temperature was explained by conduction loss and theory of single polaron hopping of charge carriers suggested by Elliot and Shimakawa for chalcogenide glasses. The experimental results show that a.c. conductivity follows the power law where s<1 and value of s decreases with the increase of temperature. The present findings of a.c. conductivity and variation of s with temperatures are reasonably well interpreted in terms of CBH model.
关键词： a c conductivity,dielectric relaxation,Chalcogenide glasses,CBH model,activation energy.
更新于2025-09-10 09:29:36
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Characterization of CuInSTe/CdS Heterojunctions
摘要： In this work, the role of substrate temperature in the range (293-423)K on the structure and microstructure of CuInSTe thin films was investigated. The results showed that the structure was amorphous for films prepared at ambient temperature Ts=293Kwhile it was polycrystalline for films prepared at high temperature. The grain size and roughness increased with increasing substrate temperature. The frequency and temperature dependencies upon AC conductivity were investigated in the frequency range 100Hz-10MHz and temperature of heat treatment in the range of 303-453K. The AC activation energy was found to increase from 0.1132 to 0.1258 eV with increasing substrate temperature from 293 to 423K and decrease to 0.0962 eV with increasing frequency from 100 to 107 Hz. The exponents show a nonsystematic sequence with the increment of substrate temperature. The obtained results gave indication t hat there is a relation between the structure and preparation temperature as well as heat treatment. According to the current-voltage characteristic, the CuInSTe/CdS heterojunction prepared at substrate temperature of 423K showed the best electrical characteristics under illumination conditions.
关键词： Activation energy,Heterojunction,quaternary alloy CuInSTe,dielectric properties,Thin films
更新于2025-09-10 09:29:36
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Structural, morphological, optical and dielectric properties of M <sup>3+</sup> /PVA/PEG SPE Films (M = La, Y, Fe or Ir)
摘要： Low band gap polymer complexes are promising due to its flexibility, and exhibiting electronic and optical properties of inorganic semiconductors. The effect of PEG on the physical properties of PVA was evaluated. Then, blend (PVA: PEG = 50:50) doped with rare earth (La or Y) and transition metal (Fe or Ir) chlorides to obtain solid polymer electrolyte films. XRD shows that adding PEG to PVA results in a new peak, 2θ = 23o with increased intensity as PEG ratio increases. However, doping with La3+, Fe3+ or Ir3+ eliminate this peak and decrease the crystallinity. SEM exhibits significant changes in the morphology of films. FTIR confirms miscibility between PVA & PEG and the complexation of the salts. The optical band gap (Eg) of PVA ~ 5.37 eV, decreased slightly by blending with PEG. While it decreased significantly to 2.64 eV and 2.78 eV after doping with Fe3+ or Ir3+. There are a consistency between Eg values obtained by Tauc's model and that obtained from the optical dielectric loss. The dielectric constant and loss, in temperature range 303–405 K & frequency range 1.0 kHz ‐ 5.0 MHz, indicate one or two relaxation peak(s) depending on the film composition. Accordingly, conduction mechanism varied between correlated barrier hopping and large polaron tunneling. The DC conductivity was strongly depend on the dielectric loss. The transition metal salts appear to be more effective than the rare earth ones in increasing σac of films to higher values that candidates them in semiconductors industry.
关键词： conduction mechanism,low band gap polymers,activation energy,PVA/PEG blend,rare earth metal complexation,solid polymer electrolyte
更新于2025-09-09 09:28:46
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Influence of Pb on structure, optical and electrical properties of Zn1-XPbXS semiconductor compounds at low temperatures
摘要： Zn1-XPbXS (x = 0–0.4 in steps of 0.1) ternary semiconductor samples have been prepared by co-precipitation method. The structural, optical and electrical studies have been carried out on all these samples to understand the influence of Lead on these properties. X-ray diffractograms showed that all Zn1-XPbXS samples have poly-crystalline nature with Hexagonal phase. The room temperature optical absorption studies revealed that energy gap decreases with increase of Pb in Zn1-XPbXS compounds. The temperature-dependent conductivity, measured in the range 300–4 K, led to understand that the conduction mechanisms at 60 K and 30 K are different. The activation energies evaluated at low (300–60 K) and very low temperature (60–30 K) regions are 38.03–32.58 meV and17.99–13.56 meV respectively. Activation energy and conductivity of Zn1-XPbXS samples increase with the increase of Pb. The samples exhibited low freezing temperature points indicating the possibility of their use in low temperature device applications.
关键词： Ternary semiconductor,Energy gap,Activation energy,Electrical conductivity
更新于2025-09-04 15:30:14