Room Temperature Annealing Research Articles

Radiation-induced electron and hole traps in Ge1 − xSnx (x = 0–0.094)

The band structure of germanium changes significantly when alloyed with a few percent concentrations of tin, and while much work has been done to characterize and exploit these changes, the corresponding deep-level defect characteristics are largely unknown. In this paper, we investigate the dominant deep-level defects created by 2 MeV proton irradiation in Ge1 − xSnx (x = 0.0, 0.020, 0.053, 0.069, and 0.094) diodes and determine how the ionization energies of these defects change with tin concentrations. Deep-level transient spectroscopy measurements approximate the ionization energies associated with electron transitions to/from the valence band (hole traps) and conduction band (electron traps) in the intrinsic regions of p-i-n diode test structures. The prominent deep-level hole traps may be associated with divacancies, vacancy–tin complexes, and vacancy–phosphorous complexes (V2, V–Sn, and V–P, respectively), with the presumed V–P hole trap dominating after room temperature annealing. The ionization energy level of this trap (approximated by the apparent activation energy for hole emission) is close to the intrinsic Fermi level in the 0% and 2% Sn devices and decreases as the tin concentration is increased, maintaining an approximately fixed energy spacing below the indirect conduction band edge. The other hole traps follow this same trend, and the dominant electron trap ionization energies remain roughly constant with changes in tin concentrations, indicating they are likewise pinned to the conduction band edge. These results suggest a pattern that may, in many cases, apply more generally to deep-level defects in these alloys, including those present in the “as-grown” materials.

Self-Annealing Behavior of Electroplated Cu with Different Brightener Concentrations

The self-annealing (room-temperature annealing) behavior of electroplated Cu has recently received a great deal of attention from the microelectronics industry because its remarkable microstructure transition is closely related to several crucial reliability issues, including substrate warpage, pinhole formation, corrosion, and electrical resistivity. Organic additives (e.g., brightener and leveler) in the electrolyte are indispensable for the superfilling of electroplated Cu in blind-/through-hole structures, and their effects on the Cu self-annealing behavior should be quantitatively characterized. We investigated the effect of brightener concentration (Cb) on the crystallographic transition of electroplated Cu (including the evolutions of the grain size, grain boundaries, and grain orientation) by means of X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and high-resolution transmission electron microscopy (HRTEM) during self-annealing. Furthermore, the mechanical properties of electroplated Cu (hardness and Young’s modulus) resulting from different Cb were investigated through nanoindentation testing. The concentration depth profiles of the impurities (Cl, N, C, and S) in the electroplated Cu were characterized by time-of-flight secondary ion mass spectrometry (TOF-SIMS). These investigations showed that Cb is a dominant factor of the Cu self-annealing behavior and mechanical properties, and a sufficient Cb is required for the initiation of a remarkable crystallographic transition even at room temperature.

Stress relaxation in asymmetric bistable composites: Experiments and simulations

In the last years, bistable composite structures are finding interest in several aeronautical applications such as power harvesting devices or morphing applications on very small aircraft/drones, not needing servo-activated control systems. Residual stresses, developed upon cooling after curing, leads to warped the composite laminates. Several batches of unsymmetrical and unbalanced [0°/90°] laminates were cured in an autoclave according to a standard temperature cycle, following the pre-preg supplier suggested curing cycle. In order to increase the thermal stresses (and hence the bistability phenomenon), these laminates were removed from the autoclave immediately after the curing reaction and rapidly cooled down at room temperature not applying the indicated cool rate between 2 and 5 °C min−1. During storage at room temperature, thermal stresses changed over time, indicating that asymptotic stress relaxation occurs. The first part of this work looks at residual stress characterization of bistable composite plates measuring the changes of shape observed during room temperature annealing. Rectangular plates were produced and the bistable geometric shapes were accurately assessed using a laser scanner system over several days, in order to monitor the curvature changes due to stress relaxation. Then phenomenological viscoelastic predicting models were proposed for a quick estimate for the strain/stress relaxation phenomenon. The loss of bistability was demonstrated with the help of numerical simulation and experimental testing. The final goal was to gain a better knowledge of the relation between processing and final shape of bistable laminates, in order to make them suitable for application on small air vehicles.

Response of Waveguide-Integrated Germanium-on-Silicon p-i-n Photodiodes to Neutron Displacement Damage

The effects of 14-MeV neutron displacement damage (DD) on waveguide (WG)-integrated germanium-on-silicon p-i-n photodiodes (PDs) for silicon photonics have been investigated up to the fluences of $7.5\times 10^{12}$ n/cm2 (14 MeV) or $1.4\times 10^{13}\,\,\text{n}_{1\text {-MeV}_{\mathrm{ eq}}}$ /cm2(Si). This article includes the measurements of dark current–voltage characteristics across temperature from 150 to 375 K, measurements of PD junction capacitance, spectral response measurements from 1260 to 1360 nm, and frequency-response measurements. The devices are found to be susceptible to DD-induced carrier removal effects; however, they also continue to operate without meaningful impact to performance for the DD dose levels examined. Since the PD test chips include silicon photonic integrated grating couplers and WGs, which carry the optical signal to the PD, some assessment of the impact of DD on these passive devices can also be inferred. This article does not examine the short-term annealing or transient behavior of the DD, and instead, it has only considered the lasting damage that remains after any initial period of room-temperature annealing.

Cold-rolling & annealing process for nuclear grade wrought FeCrAl cladding alloy to enhance the strength and ductility

Abstract FeCrAl alloy is a good candidate as accident-tolerant fuel (ATF) cladding material. While cold-working is a preferred routine for fabricating thin-wall FeCrAl tubes, the effects of cold-rolling treatment on the microstructural features and the tensile properties are still unclear. In this study, a successive process containing hot-rolling and annealing at 800°C, cold-rolling at room temperature and final annealing at 750°C were developed for a wrought Fe-13Cr-4.5Al-2Mo-2.5Nb-0.1Ti- 0.1V-0.05Y alloy. The alloy with 60% hot-rolling and 40% cold-rolling reductions exhibited an ultimate tensile strength of 869MPa and a total elongation of 20.9%. The good mechanical properties were attributed to the recovery microstructure with much refined grain size, the dense dislocation network forming the sub-grain boundaries and the Laves precipitates distributed both along the grain or sub-grain boundaries and in the ferritic matrix. The alloy also exhibited a weak deformation texture. The satisfactory mechanical properties together with the nearly isotropic grain morphology and the weak rolling texture provide it good potential for application as ATF cladding materials.

Effect of room-temperature annealing on structures and properties of SSBR/BR blends and SSBR/BR/SiO2 composites

Room-temperature annealing process lies between high-temperature mixing process and high-temperature vulcanization process in rubber processing technology, and definitely affects the performances of rubber composites. In this work, the influences of room-temperature annealing on the structures and properties of unfilled SSBR/BR blends and silica-filled SSBR/BR composites have been evaluated in detail. For the unfilled SSBR/BR vulcanizates, the tensile strength, tear strength and fatigue resistance deteriorate due to the reduced rubber matrix strength with lower crosslinking density and less chain entanglements with annealing time extending. While for the SSBR/BR/SiO2 vulcanizates with dual networks including filler-filler networks and polymer-polymer networks, the tensile strength and fatigue resistance reduce, the tear strength, dynamical properties concerning abrasion, heat built-up and rolling resistance improve obviously with extending annealing time, which are attributed to the enhanced filler-polymer interactions, severe silica flocculation, and reduced internal hysteresis loss with annealing time prolonging. This work is expected to provide fundamental understanding of the annealing process in the rubber processing technology for development of high-performance rubber composites.

Degradation and annealing characteristics of NPN SiGe HBT exposed to heavy ions irradiation

In this study, the performance degradation and annealing behavior of NPN SiGe HBT exposed to swift heavy ion irradiation were investigated. The direct current (DC) characteristics such as forward Gummel, junction leakage current and Early voltage were studied to quantify the irradiation tolerance. Base current and junction leakage current was found to increase after irradiation. The recovery of electrical parameters was characterized after room-temperature isothermal annealing and elevated-temperature isochronal annealing. An obvious temperature-dependence effect was found in the subsequent annealing process. Significant recovery existed in the high-temperature isochronal annealing process, while less was found in the room temperature self-annealing process. The different annealing behaviors of ionization damages and displacement damages are demonstrated to be responsible for various recoveries under room temperature and elevated temperature. The underlying physics mechanisms are discussed in detail.

Self-healing behavior of Inconel 617B superalloy

In the present study, the self-healing behavior of Inconel 617B superalloy (617B), used as a high-temperature material, was investigated through both preliminary test consisting of room-temperature tension and annealing and creep rupture test. Micro-cracks in the solution-treated specimen, which had been fractured at room temperature, were filled in by the precipitation of M23C6 and the segregation of B, C, and S after annealing at 800 °C for 16 h. Due to this healing effect and dislocation recovery, a 33% pre-strained and annealed specimen exhibited the longer total elongation, compared to the specimen strained until fracture without annealing after 33% pre-strain. Finally, creep rupture tests revealed that the creep strength of 617B is higher than Inconel 617 superalloy (617) due to the self-healing effect by the high-temperature precipitation of M23C6 and the segregation of B, C, and S as well as grain boundary strengthening of B and C.

Preparation and Capacitance Properties of Nickel-Cobalt Sulfide/Graphene Composites

In order to explore the supercapacitor electrode material with high energy density, a composite material that nickel-cobalt sulfide loaded in graphene (NiCo2S4@rGO) with core-shell structure was successfully prepared by hydrothermal, room temperature vulcanization and annealing. The core-shell structure of the material greatly increased the contact area between the material and the electrolyte and improved the electrochemical performance. In addition, the energy density has been significantly improved. NiCo2S4@rGO was characterized by field emission scanning electron microscopy (SEM), high-resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectrometer. The electrochemical properties of the material were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results show that the capacitance can reach 1100 F/g at the current density of 0.5 A/g. Furthermore, the NiCo2S4@rGO as positive electrode and reduced graphene oxide (rGO) as negative electrode were assembled into an asymmetric supercapacitor (ASC). The device exhibits a high energy density of 74.78 Wh/Kg at a power density of 400 W/Kg, as well as excellent cycling stability of 88.9% after 3 000 cycles, which reflects the excellent electrochemical performance of the material.

Recrystallization of cold rolled oxide dispersion strengthened copper during room temperature annealing

Static discontinuous recrystallization was studied during room temperature annealing of a newly designed 80% room temperature rolled oxide dispersion strengthened copper. At early stages of annealing, fine new oriented nanosized/submicron grains were recrystallized in the unique matrix of single brass-oriented deformed grain. Upon longer annealing time up to 14 months, the size, area fraction and number density of the recrystallized grains increased significantly along with changing the crystallographic textures. The analysis of misorientation angle distribution of boundaries indicated transformation of low angle boundaries to high angle boundaries results in nucleation of recrystallized grains by significant contribution of static recovery. Furthermore, the constant level of mechanical hardness after recrystallization was interpreted by the balance between grain size hardening, oxide particle hardening and strain hardening.

Synthesis Thin Films SnO2 with Doping Indium by Sol-gel Spin coating

Abstract:This research is an experimental study that aims to support the temperature and variation of doping in making thin films. The temperature variations at room temperature annealing, 50, 100, 150, and 200oC, and doping variations of 0, 5, 10, 15, 20, and 25%. The method used in this study is sol-gel spin coating. The results showed that thin films at low temperatures were more transparent than higher temperatures and the increase percentage doping causing thin films to be more transparent. Keywords:Thin Films; SnO2; Indium, Sol-gel, Spin Coating.

High energy swift heavy ion irradiation and annealing effects on DC electrical characteristics of 200 GHz SiGe HBTs

Abstract The total ionizing dose (TID) and non ionizing energy loss (NIEL) effects of 100 MeV phosphorous (P7+) and 80 MeV nitrogen (N6+) ions on 200 GHz silicon-germanium heterojunction bipolar transistors (SiGe HBTs) were examined in the total dose range from 1 to 100 Mrad(Si). The in-situ I–V characteristics like Gummel characteristics, excess base current (ΔIB), net oxide trapped charge (NOX), current gain (hFE), avalanche multiplication (M − 1), neutral base recombination (NBR) and output characteristics (IC-VCE) were analysed before and after irradiation. The significant degradation in device parameters was observed after 100 MeV P7+ and 80 MeV N6+ ion irradiation. The 100 MeV P7+ ions create more damage in the SiGe HBT structure and in turn degrade the electrical characteristics of SiGe HBTs more when compared to 80 MeV N6+. The SiGe HBTs irradiated up to 100 Mrad of total dose were annealed from 50 °C to 400 °C in different steps for 30 min duration in order to study the recovery of electrical characteristics. The recovery factors (RFs) are employed to analyse the contribution of room temperature and isochronal annealing in total recovery.

Fabrication of Cr2AlC coating from a cost-efficient Cr–Al–C target by arc ion plating

In the present research, a novel cost-efficient chromium (Cr)–aluminum (Al)–carbon (C) target hot-pressed at 650°C with chromium:aluminum:carbon = 2:1:1 (molar ratio) was applied to fabricate chromium aluminum carbide (Cr2AlC) coatings by the arc ion plating method at room temperature and subsequent annealing. Scanning electron microscopy, X-ray diffraction and transmission electron microscopy were used to characterize the coatings and the target. The results showed that the chromium–aluminum–carbon target mainly comprised chromium, carbon and chromium aluminum compound (Cr9Al17). By arc ion plating with the hot-pressed chromium–aluminum–carbon target and subsequent annealing at 620°C, polycrystalline chromium aluminum carbide coating with minor chromium carbide (Cr3C2) was obtained. The as-prepared chromium aluminum carbide coating was dense and crack-free, and there existed macroparticles in the coating. Transmission electron microscopy observations revealed that the as-prepared chromium aluminum carbide coating exhibited a multilayer structure vertical to the growth direction. The coating possessed hardness and adhesion strength of 8·8 ± 0·8 GPa and 42 ± 17 MPa, respectively, which could meet the basic requirement of high-temperature protective coating.

Heavy ion induced upset errors in 90-nm 64 Mb NOR-type floating-gate Flash memory**Project supported by the National Natural Science Foundation of China (Grant No. 616340084), the Youth Innovation Promotion Association of CAS (Grant No. 2014101), the International Cooperation Project of CAS, and the Austrian-Chinese Cooperative R&D Projects (Grant No. 172511KYSB20150006).

Upset errors in 90-nm 64 Mb NOR-type floating-gate Flash memory induced by accelerated 129Xe and 209Bi ions are investigated in detail. The linear energy transfer covers the range from 50 to 99.8 MeV/(mg/cm2). When the memory chips are powered off during heavy ions irradiation, single-event-latch-up and single-event-function-interruption are excluded, and only 0->1 upset errors in the memory array are observed. These error bit rates seem very difficult to achieve and cannot be simply recovered based on the power cycle. The number of error bits shows a strong dependence on the linear energy transfer (LET). Under room-temperature annealing conditions, the upset errors can be reduced by about two orders of magnitude using rewrite/reprogram operations, but they subsequently increase once again in a few minutes after the power cycle. High-temperature annealing can diminish almost all error bits, which are affected by the lower LET 129Xe ions. The percolation path between the floating-gate (FG) and the substrate contributes to the radiation-induced leakage current, and has been identified as the root cause of the upset errors of the Flash memory array in this work.

FET-based radiation sensors with Er 2 O 3 gate dielectric

Abstract Pre-irradiation device characteristics, gamma radiation response, and possible use in radiation dosimetry have been investigated for MOSFETs with a 100 nm thick Er2O3 gate dielectric. The performance of these novel devices has been compared with that of commercial pMOS dosimeters (RadFETs) with a standard SiO2 gate oxide of the same thickness. The radiation sensitivity of the Er2O3 is significantly higher than that of SiO2, and this is particularly pronounced at lower dose levels. Significantly larger numbers of positive charges are trapped in the Er2O3 dielectric than in SiO2 during irradiation exposure, resulting in increased threshold voltage shift. After two weeks of room temperature annealing, 11.9% and 24.0% fading have been observed in SiO2 and Er2O3 samples, respectively. Higher fading for Er2O3 may be related to higher number of shallow traps close to the dielectric/silicon interface. These initial results are promising for the possible use of Er2O3 as a new gate dielectric in pMOS dosimeters. The observed enhancement of device sensitivity can be a milestone for the introduction of the pMOS dosimeters in personal dosimetry applications.

Synthesis and Structure–Property Relationship of Biobased Biodegradable Poly(butylene carbonate-co-furandicarboxylate)

A series of biobased poly(butylene carbonate-co-furandicarboxylate) (PBCF), are synthesized through a two-step polycondensation reaction. Chemical structures, thermal properties, crystallization behaviors, mechanical properties, barrier properties, and enzymatic degradation of PBCFs are investigated. The linear variation of the glass transition temperatures with the content ratio confirms the good miscibility between butylene carbonate (BC) and butylene furandicarboxylate (BF) units. BF segments could crystallize in most contents under different temperatures. Consequently, mechanical properties of these copolymers depend not only on the composition but also on the annealing conditions. Long-time annealing at room temperature or short-time annealing under high temperature could tremendously increase the tensile modulus. For room-temperature annealing, the formation of less perfect crystals of the poly(butylene furandicarboxylate) (PBF) could interpret the enhancement of modulus. On the other hand, the high...

Neutron irradiation test of Hamamatsu, SensL and AdvanSiD UV-extended SiPMs

In this paper, we report the measurement of the neutron radiation hardness of custom Silicon Photomultipliers arrays (SiPMs) manufactured by three companies: Hamamatsu (Japan), AdvanSiD (Italy) and SensL (Ireland). These custom SiPMs consist of a 2×3 array of 6×6 mm2 monolithic cells with pixel sizes of respectively 50 μm (Hamamatsu and SensL) and 30 μm (AdvanSiD). A sample from each vendor has been exposed to neutrons generated by the Elbe Positron Source facility (Dresden), up to a total fluence of ∼ 8.5 × 1011 n1 MeV/cm2. Test results show that the dark current increases almost linearly with the neutron fluence. The room temperature annealing was quantified by measuring the dark current two months after the irradiation test. The dependence of the dark current on the device temperature and on the applied bias have been also evaluated.

Enhancement of mechanical and electrical properties of Al-RE alloys by optimizing rare-earth concentration and thermo-mechanical treatment

Al-based immiscible systems, such as Al-RE (rare earth), seem to be promising materials for high conductivity conductors as RE alloying elements have zero solubility in Al and thus are less detrimental for electrical conductivity. The intermetallic phases, precipitated as small particles and uniformly distributed in the alloy's volume, may significantly increase the mechanical strength and thermal stability of alloy. However, the immiscible element compound concentration should be controlled as an excessive amount might result in a loss of electrical conductivity. Therefore, the optimization of RE concentration to obtain the best combination of mechanical strength and electrical conductivity is considered in this research. It focuses also on the effect of high-pressure torsion (HPT) and post deformation annealing temperature on mechanical and electrical properties of Al-RE (La + Ce) alloy. Alloys with total Ce and La concentrations of 2.5, 4.5 and 8.5 wt % are subjected to HPT at room temperature and subsequent annealing in the range of temperatures 230–400 °C. The optimal concentration of RE and processing parameters for enhancement of both mechanical strength and electrical conductivity are defined.

Annealing Effects on the Normal-State Resistive Properties of Underdoped Cuprates

The influence of room-temperature annealing on the parameters of the basal-plane electrical resistance of underdoped YBa$_2$Cu$_3$O$_{7-\delta}$ and HoBa$_2$Cu$_3$O$_{7-\delta}$ single crystals in the normal and superconducting states is investigated. The form of the derivatives $d\rho(T)/dT$ makes it possible to determine the onset temperature of the fluctuation conductivity and indicates a nonuniform distribution of the labile oxygen. Annealing has been revealed to lead to a monotonic decrease in the oxygen deficiency, that primarily manifests itself as a decrease of the residual resistance, an increase of $T_c$, and a decrease of the Debye temperature.

Quenching and room-temperature annealing effects on the conductivity of underdoped HoBa2Cu3O7−δ

The effects of quenching from 600[Formula: see text]C and subsequent room-temperature annealing on the basal-plane electrical resistivity of underdoped HoBa2Cu3O[Formula: see text] single crystals are investigated. Regions with different superconducting transition temperatures, [Formula: see text], have been revealed in the sample after quenching and attributed to a non-uniform distribution of the labile oxygen in the sample volume. Room-temperature annealing has been revealed to lead to an increase of [Formula: see text] of all regions and a decrease of their number, attributed to the coalescence of clusters of oxygen vacancies. The temperature dependence of the resistance in the normal state is characterized by a decrease of the residual resistivity and the phonon scattering coefficient.