Activation Energy For Annealing Research Articles

New properties of boron-oxygen dimer defect in boron-doped Czochralski silicon

Silicon doped with boron is the most widely used material in modern microelectronic devices based on p-Si. Therefore, it is important to thoroughly understand boron’s role in the processes of defect-impurity interaction in Si both on growing the material and during operation of devices. In this work, interactions of boron with oxygen in Si are investigated by studying boron absorption intracenter transitions, which are known to be highly sensitive to the local environment. In boron-doped Si, two lines with maxima at 228 and 261.3 cm−1 were detected. The linear dependence of lines intensity on boron concentration and the quadratic on oxygen content testifies that the defect responsible for the lines can be identified as BsO2i. The observed absorption lines correspond to the transitions from the ground to the excited states of boron, which are shifted toward lower frequencies relative to the main transitions due to a deformation perturbation from neighboring oxygen atoms. The activation energy of annealing and ionization energy of defect are determined. The properties of the registered ВsO2i defect differ from the known ВsO2 associated with the light-induced degradation of solar cells by local configuration. The data obtained testify that the ВsO2i defects with different properties can be formed in Si and must be taken into account when developing Si:B-based devices because they can play an important role in charge carrier transfer and affect the electrical and optical parameters of the material.

Evaluation of static recrystallization and grain growth kinetics of hot-rolled AZ31 alloy

The static recrystallization/grain growth kinetics of the AZ31 (Mg-3Al-1Zn, wt%) alloy were investigated employing Vickers microhardness and electron backscatter diffraction (EBSD) measurements. The AZ31 alloy was subject to a hot-rolling for 70% of thickness reduction and then annealed at various temperatures (150°C, 250°C, and 350°C) from 5 min to 24 h. First, the static recrystallization kinetics were analysed by means of the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. The results showed that the recrystallization occurred under two regimes both involving their own Avrami exponent/ activation energy. In regime I, the Avrami exponent was found in the range of 1.5-0.35 depending on the annealing temperature and activation energy of 74.1±5.7 kJ×mol-1. In regime II, an identical value of Avrami exponent was found (0.1-0.2) and a very low activation energy of 14.8±0.7 kJ×mol-1 was found for all annealing conditions. Non-random nucleation sites such as shear bands were considered as the main factor responsible for the deviation from the JMAK model. Moreover, the grain growth kinetics was well fitted by the general equation where . Accordingly, Qg = 109± 0.2 kJ×mol-1 which is median between grain boundary diffusion and bulk diffusion values for Mg and its alloys. The derived activation energies were discussed in terms of influencing factors such as solute drag, formation of basal texture, and microstructural heterogeneities like shear bands and twinning.

Crystal defects induced by evaporation of Co and Zn on the structure and microwave properties of Ba(Co0.7Zn0.3)1/3Nb2/3O3 ceramics

There is no significant difference in grain size, B-site 1:2 ordering degree and domain structure of Ba(Co0.7Zn0.3)1/3Nb2/3O3 (BCZN) ceramics annealed at 1300 °C–1350 °C for 30 h. In contrast, the Q × f values of BCZN ceramics annealed at 1350 °C for 30 h decreases sharply to 53,900 GHz (at 7 GHz) from ~84,700 GHz for its counterpart annealed at 1300 °C for 30 h. EPMA results show that the deficiency of zinc and cobalt appears in the BCZN ceramics. Co and Zn loss in BCZN ceramics leads to the formation of crystal defects that have a significant influence on electrical properties and dielectric loss. With the increasing annealing temperature, the resistivity and activation energy Ea of as-annealed BCZN ceramics decrease, indicating higher crystal defect density in ceramics. The crystal defects rather than B-site 1:2 ordering play a dominant role in determining the dielectric loss of BCZN ceramics containing evaporative Zn and Co.

Use of infrared light-emitting diodes to determine dosimetric characteristics of MgO:Tb,Gd,Li via the optically stimulated luminescence technique

In this study, the temperature dependence of Infrared Stimulated Luminescence (IRSL) in MgO:Tb,Gd, Li samples were investigated and the basic dosimetric properties were examined for the radiation dosimetry. Terbium, gadolinium, and lithium doped MgO were synthesized using the solution combustion synthesis method, and the characterization of the material was performed by X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. The effects of the dopants were investigated by specifying the radioluminescence (RL), thermoluminescence (TL), and optically stimulated luminescence (OSL-blue stimulation/IRSL-infrared stimulation) curves of the MgO:Tb,Gd, Li phosphor. Decay curves of the light flash vs. time showed that the MgO:Tb,Gd, Li was most readily discharged by infrared stimulation. The temperature dependence of the IRSL samples was investigated between 50 and 230 °C. The optimized readout temperature was determined as 120 °C achieving the maximum IRSL intensity. It was shown that there are traps responsible for TL peaks below 200 °C which could be suggested as the source of the IRSL signals for the studied MgO:Tb,Gd, Li samples. The high-temperature TL peak nearly at 400 °C was not affected by infrared stimulation and did not contribute to the obtained IRSL signals. The dosimetric properties such as reusability, multi-readability, dose-response, and fading were examined for applicability to radiation dosimetry. The thermal stability of the sample was investigated using the isothermal annealing technique and activation energy and frequency factor of the traps responsible for IRSL signal were estimated as 0.62 eV and 106 Hz, respectively. The MgO:Tb,Gd, Li luminescent has several properties in its favor. It has been shown that the IRSL signals of the Tb, Gd, and Li doped MgO sample can be investigated and examined as a radiation dosimeter.

An Analytical Approach to Study Annealing Induced Interdiffusion of In and Ga for Truncated Pyramidal InAs/GaAs Quantum Dots

A strain-assisted model for studying the annealing induced interdiffusion of constituent atoms in truncated pyramidal InAs/GaAs self-assembled quantum dot (QD) is developed. In our model, we have considered the equiprobable diffusion of Ga and In atoms in and out of the QD system, thereby resulting in the formation of In rich In1-xGaxAs as the QD material and a combination of Ga rich InxGa1-xAs and GaAs barrier material. This assumption is supported by the high-resolution cross-sectional transmission electron microscopy (HRTEM) images and high-resolution X-ray diffraction (HRXRD) plots of the as-grown and annealed samples. First principle calculations are utilized to evaluate the strain and annealing temperature dependent activation energy, which further assists to solve the Fickian diffusion model. Our simplistic model provides a detailed insight into the effect of annealing phenomenon on the bimodal Photoluminescence (PL) spectra of molecular beam epitaxy (MBE) grown InAs/GaAs QDs, which have evolved as a potential system for innumerous applications including single photon sources, quantum computers, spin LEDs, LASERs and Infrared Photodetectors.

Thermal annealing effects of InGaAs (1.0 eV) and InGaAs (0.7 eV) sub-cells of inverted metamorphic four junction (IMM4J) solar cells under 1 MeV electron irradiation

In this work, thermal annealing effects of InGaAs (1.0 eV) and InGaAs (0.7 eV) sub-cells for inverted metamorphic four junction (IMM4J) solar cells after being irradiated by 1 MeV electrons are investigated by using light <i>I</i>-<i>V</i> characteristic, dark <i>I</i>-<i>V</i> characteristic and spectral response. Annealing temperature range is 60–180 ℃ and annealing time is 0-180 min. The results indicate that the open-circuit voltage <i>V</i><sub>oc</sub>, short-circuit current <i>I</i><sub>sc</sub>, and maximum power <i>P</i><sub>max</sub> of two sub-cells are gradually recovered with annealing time increasing, and the rate of recovery increases with annealing temperature increasing. Besides, the recovery rate of InGaAs (1.0 eV) sub-cell is less than that of InGaAs (0.7 eV) sub-cell under the same annealing temperature and time. Double exponential model is used to fit the dark <i>I</i>-<i>V</i> curve for the key parameters (the serial resistant <i>R</i><sub>s</sub>, the parallel resistant <i>R</i><sub>sh</sub>, the diffusion current <i>I</i><sub>s1</sub> and the recombination current <i>I</i><sub>s2</sub>). It is found that <i>R</i><sub>s</sub>, <i>I</i><sub>s1</sub> and <i>I</i><sub>s2</sub> of two sub-cells decrease gradually and <i>R</i><sub>sh</sub> increases during annealing and the rate of recovery increases with annealing temperature rising. However, the recovery of <i>I</i><sub>s1</sub> and <i>I</i><sub>s2</sub> of InGaAs(1.0 eV) are much greater than that of InGaAs(0.7 eV). The equivalent model between short-circuit current density (<i>J</i><sub>sc</sub>) and defect concentration (N) induced by irradiation and annealing is established. <i>N</i> changes follow the first reaction kinetics, and the rate constant follows the Arrhenius equation with the annealing temperature. Therefore, the thermal annealing activation energy of InGaAs(1.0 eV) and InGaAs(0.7 eV) sub-cells are 0.38 eV and 0.26 eV, respectively. These efforts will contribute to the IMM4J solar cells, in particular, to space-based applications.

(Invited) Al+ Ion Implanted 4H-SiC: Electrical Activation versus Annealing Time

The selected area doping by ion implantation is often used in the fabrication of 4H-SiC electronic devices; DMOSFETs and JTE are here cited as examples. In the ion implantation technology, the key parameters are: implantation temperature, dose rate per ion energy, ion implanted dopant depth profile, post implantation annealing temperature, and post implantation annealing time. In the case of 4H-SiC, the most of the litterature focus on finding the post implantation annealing parameters that maximize the doping efficiency per ion implanted dopant concentration, or, that give the sufficient electrical activation for obtaining the desired device performance. This results in a multitude of reported electrical data, taken in heterogeneous samples. Recently, an empirical model for previewing the electrical activation per ion implanted dopant species versus dopant concentration has been proposed [1] on the base of published data. This model [1] could be a useful tool for sufficiently reliable device designs. Nevertheless, recent results on the electrical activation of ion implanted P and Al in 4H-SiC [2-3] show that the data trends used in [1] may require adjustments. Moreover, a full description of the thermodynamics controlling the phenomenon of the electrical activation of ion implanted dopants in 4H-SiC, should require dedicated experiments; examples of which can be found in [4-5]. It is relevant to cite the fact that the results of [4] allowed the authors to perform realistic previsions about the electrical trasport in Al ion implanted 4H-SiC after post implantation annealing at a temperature and for times never explored before, as shown in [6]. The present work will resumes the latest results on the electrical activation of aluminum [2] and phosphorous [3] ion implanted in 4H-SiC with typical concentration values for n-channel DMOSFETs. These values are in the range 3×1018 - 1×1019 cm-3. Post implantation annealing temperature is relative low: 1600 °C. This is a conservative value for minimizing step bunching formation at the oxide/semicondutor interface in the channel region. The annealing time ranges from 5 min to 15 h. The temperature dependence of resistivity and Hall coefficent is measured in the range 70-640 K. Experimental data are analysed to extract donor and acceptor concentration, dopant compensation, and carrier mobility. For comparison purposes, both published and original results obtained for identical ion implanted dopant species and similar ion implanted dopant concentration in high purity semi insulating (HPSI) 4H-SiC, but higher post implantation annelaing temperature, will be shown too. The aim of this work is to produce results that help in featuring the balance between electrical activation and compensation as far as the annealing time increases at a fixed annealing temperature. The DMOSFETs doping configuration has been chosen because timely. [1] V. Simonka et al., "Transient model for the electrical activation of aluminium and phosphorous-implanted silicon carbide", J. Appl. Phys. 123, 235701 (2018). [2] R. Nipoti et al., "Low concentration Aluminum ion implantation in 4H-SiC", submitted to ICSCRM2019, Tokyo, Sept. 29 - Oct. 4, 2019. [3] A. Parisini et al., "Phosphorous doping by ion implantation in 4H-SiC DMOSFETs", submitted to ICSCRM2019, Tokyo, Sept. 29 - Oct. 4, 2019. [4] R. Nipoti et al. "About the Electrical Activation of 1×1020 cm-3 Ion Implanted Al in 4H-SiC at Annealing Temperatures in the Range 1500 - 1950°C", Mater. Sc. Forum, 924, 333-338 (2018). [5] R. Nipoti et al., "Activation energy for the post implantation annealing of 1019 cm-3 and 1020 cm-3 ion implanted Al in 4H SiC.", proceedings of ECSCRM2018, Birmingham, accepted for publication in Mater. Sc. Forum on Jan. 29, 2019. [6] R. Nipoti et al., "1300°C Annealing of 1×1020 Al+ Ion Implanted 3C-SiC", proceedings of ECSCRM2018, Birmingham, accepted for publication in Mater. Sc. Forum on Jan. 29, 2019.

Annealing of fission fragment tracks in CR-39 nuclear track detector — Phenomenological model

Abstract In this short paper, a new model for annealing of latent nuclear tracks is developed. Physical phenomenological picture or foundation of the model is presented using experimental spectra of 252Cf fission fragment tracks annealed at 75–175 °C for 5–30 min. Here, annealing of nuclear tracks refers to the reduction of track lengths during annealing or thermal treatment. A new annealing parameter (t/T2) is identified in the model, which is useful in understanding and analysis of annealing of nuclear tracks. In definition of the annealing parameter above, the quantities t and T are annealing time and temperature, respectively. The model allows deduction of the activation energy of annealing simultaneously from track annealing data, collected over all the annealing conditions (t, T). This model provides a quick methodology to study kinetics of nuclear track annealing. The presented model is validated using the experimental results of annealing of fission tracks in CR-39 detector. The determined value of activation energy of annealing is 0.204 ± 0.012 eV. Presented results and discussion can be extended to swift heavy ion (SHI) tracks.

An effective research for diffusion annealing temperature and activation energy in Au surface-layered Bi-2212 ceramic composites

This study tries to respond two fundamental questions such as (I) what is the role of Au inclusions in the Bi-2212 polycrystalline materials prepared at the diffusion annealing temperature of 600–850 °C on the stabilization of superconductivity in small homogeneous regions and (II) what are the diffusion coefficient and corresponding activation energy of Au inclusions for the Bi-2212 superconducting system. Solution of the former question is in association with the characteristic pairing and coherence transitions extracted from the detailed dc resistivity versus temperature measurements when the latter questions are answered by the change of sample resistivity after the removal of thin-layer from the surface with the aid of the Arrhenius relation for the first time. The experimental measurement results show that the optimum diffusion annealing temperature is observed to be 800 °C where the minor phase, local structural distortions, dislocations, lattice defects and disorders in the Bi-2212 compounds degrade considerably and reach the global minimum points. Similarly, the Josephson coupled energy resides in the maximum value, and thus the superconducting grains become more and more coupled due to the increment in the percolation of intergrains. Moreover, the diffusion coefficient of Au individuals is obtained to increase regularly from 3.6186 × 10−8 to 2.79278 × 10−7 cm2 s−1 with the enhancement in the diffusion annealing temperature. At the same time, the temperature-dependent diffusion coefficient and related activation energy values of Au are computed to be about 2.601 × 10− 6 cm2 s−1 and 1.523 eV, respectively. According to the results calculated, 1.523 eV is the required minimum activation energy for the penetration of Au (heavy metal) ions into the Bi-2212 crystal structure.

Annealing of the Sb-vacancy and a closely related radiation induced defect in n-type germanium

Deep level transient spectroscopy was used to study the defects induced by alpha-particle irradiation from an Am241 source in antimony doped n-type germanium. Previous investigations of the well know Sb-vacancy defect have led to the discovery of a second defect with very similar emission properties, referred to as the E′. Although both defects have similar emission rates, they have very different annealing properties. In this study we further investigated these properties of the E′ in Sb doped samples irradiated at 270K with alpha particles from an Am241 source. Laplace deep level transient spectroscopy was used to determine the concentration of each defect. An isothermal annealing study of the E′ was carried out in the temperature range 300K to 325K in 5K increments, while the Sb-vacancy was annealed out completely at 410K onwards, long after the E′ was completely annealed out. The annealing activation energy was determined through isothermal annealing profiles for both the Sb-Vacancy and the E′ as 1.05eV and 0.73eV respectively with a prefactor of 2.05 × 109s−1 and 2.7 × 108s−1.

Low-temperature activation under 150°C for amorphous IGZO TFTs using voltage bias

ABSTRACTProposed herein is a new technique of activation for the backplane of low-temperature amorphous indium gallium zinc oxide thin-film transistors (a-IGZO TFTs) by applying a bias voltage to gate, source, and drain electrodes and simultaneously annealing them at 150°C. This ‘voltage bias activation’ can be an effective method of reducing the backplane processing temperature from 300°C to 150°C. Compared with the reference a-IGZO TFTs fabricated at 300°C, the a-IGZO TFTs fabricated through voltage bias activation showed sufficient switching characteristics: 10.39 cm2/Vs field effect mobility, 0.41 V/decade subthreshold swing, and 3.65 × 107 on/off ratio. These results were analyzed thermodynamically using infrared micro-thermography. In the case of the positive gate voltage bias condition, the maximum temperature of the a-IGZO channel increased to 48°C, and this additional annealing effect and activation energy lowering compensated for the insufficient thermal energy of annealing at a low temperature (150°C). With this approach, a-IGZO TFTs were successfully fabricated at a low temperature.

Photoluminescence Analysis of Injection-Enhanced Annealing of Electron Irradiation-Induced Defects in GaAs Middle Cells for Triple-Junction Solar Cells**Supported by the National Natural Science Foundation of China under Grant Nos 10675023, 11075018 and 11375028, and the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No 20120003110011.

Photoluminescence measurements are carried out to investigate the injection-enhanced annealing behavior of electron radiation-induced defects in a GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells which are irradiated by 1.8MeV with a fluence of 1 × 1015 cm−2. Minority-carrier injection under forward bias is observed to enhance the defect annealing in the GaAs middle cell, and the removal rate of the defect is determined with photoluminescence radiative efficiency recovery. Furthermore, the injection-enhanced defect removal rates obey a simple Arrhenius law. Therefore, the annealing activation energy is acquired and is equal to 0.58 eV. Finally, in comparison of the annealing activation energies, the E5 defect is identified as a primary non-radiative recombination center.

Time-resolved positron annihilation spectroscopy study of relaxation dynamics of ion damage in fused quartz

Relaxation dynamics of ion damage in fused quartz is investigated by our newly developed pump–probe technique combining energetic ions (pump) with slow positrons (probe). This method enables determination of time-resolved positron lifetime. We study the time-dependent relaxation of ion damage, by analyzing the intensity variation in the ortho-positronium lifetime component associated with irradiation damage. For irradiation with 160 keV He ions in the temperature range of 300–573 K, the positron annihilation lifetime spectra are obtained as a function of time after ion irradiation. We observe that the relaxation time of ion damage is strongly influenced by specimen temperatures; the relaxation time constant is approximately 400 ms at room temperature (300 K) and becomes smaller with an increasing temperature. Analysis for the effect of temperature on damage accumulation reveals that the activation energy for thermal annealing of the observed damage is approximately 0.1 eV.

Towards modelling realistic ageing rates of amorphous silicon devices in operational environment

This paper presents a method to de-convolute the annealing and degradation processes of amorphous silicon devices. This will allow modelling realistic outdoor operation. Six devices underwent 14000 h indoor light exposure at different and varying thermal conditions. The devices are exposed to light at variable temperatures between 25 and 85 °C under illumination as well as annealed in the dark. The temperature set-points were altered several times during the test to gain insights on how the balance between light induced degradation and thermal annealing is shifted. Measurements show that the degradation level is largely determined by the device’s operating temperature and both processes balance themselves out without consideration of device history. This is explained by the proposed modelling approach based on the defect pool model. The key parameters in the proposed modelling approach are the effective activation energies for degradation and annealing.

Effect of hydrostatic pressure during the annealing of silicon-on-insulator films implanted with a high hydrogen-ion dose

The properties of silicon-on-insulator films implanted with high hydrogen-ion doses (∼50 at %) and annealed under a pressure of 10.5 kbar are studied using the Raman scattering (RS) method. A high degree of optical-phonon localization is detected in the films under study, which is retained to an annealing temperature of ∼1000°C and is explained by the formation of silicon nanocrystals. It is found that the activation energy of annealing of the structural relaxation of dangling bonds in films with a high hydrogen content is independent of the annealing pressure. The activation energy of growth of the crystalline phase, calculated from RS spectra is ∼1.5 eV and is independent of pressure. The effect of hydrostatic pressure consists only in a decrease in the frequency factor limiting Si-Si bond relaxation during ordering.

Electroluminescence analysis of injection-enhanced annealing of electron irradiation-induced defects in GaInP top cells for triple-junction solar cells

Direct injection-enhanced annealing of defects in a GaInP top cell for GaInP/GaAs/Ge triple-junction solar cells irradiated with 1.8MeV electrons with a fluence of 1×1015 cm−2 has been observed and analyzed using electroluminescence (EL) spectra. Minority-carrier injection under forward bias conditions is observed to enhance defect annealing in the GaInP top cell, and recovery of the EL intensity of the GaInP top cell was observed even at room temperature. Moreover, the injection-enhanced defect annealing rates obey a simple Arrhenius law; therefore, the annealing activation energy was determined and is equal to 0.51eV. Lastly, the H2 defect has been identified as the primary non-radiative recombination center based on a comparison of the annealing activation energies.

Neutron bombardment of single wall carbon nanohorn (SWCNH): DSC determination of the stored Wigner-Szilard energy

Single wall carbon nanohorn (SWCNH) were neutron-bombarded to a dose of 3.28 × 1016 n/cm2. The Wigner or stored energy was determined by a differential scanning calorimeter and was found 5.49 J/g, 50 times higher than the Wigner energy measured on graphite flakes treated at the same neutron dose. The activation energy for the thermal annealing of the accumulated radiation damage in SWCNH was determined in the range 6.3–6.6 eV against a typical activation energy for the annealing of the radiation-damaged graphite which is in the range of 1.4–1.5 eV. Furthermore the stored energy in neutron-damaged SWCNH is released at 400–430 °C while the main peak in the neutron-damaged graphite occurs at 200–220 °C. The radiation damaged SWCNH were examined with FT-IR spectroscopy showing the formation of acetylenic and aliphatic moieties suggesting the aromatic C=C breakdown caused by the neutron bombardment.

Influence of electrical performance on Cu-related defects generated by 250 keV electron irradiation in Cu (In, Ga) Se2 thin-film solar cells

High-energy electrons are known to induce Cu-related defects in Cu (In, Ga) Se2 material. CIGS cells were irradiated with electrons with the energy of 250keV at temperatures below 150K to avoid the recovery of generated defects due to a thermal annealing effect. The carrier density increased in line with increasing electron fluence. Copper vacancy (VCu) could result in increased carrier density as the shallow acceptor level (VCu) is assumed to be the main defect in the CIGS absorbing layer. In the case of 1MeV electron irradiation, however, a decrease in the carrier density of CIGS solar cells has been reported. The activation energies for the thermal annealing of defects induced by 250keV electrons differ from those induced by 1MeV electrons. The Cu-related defects in CIGS induced by 250keV electron irradiation are not thought to degrade CIGS solar cell output performance.

Study of radiation-induced damage to type III–V semiconductor compounds irradiated with γ quanta and protons using positron annihilation spectroscopy

The effect of proton and γ radiation on characteristics of the spectra for the angular distribution of annihilation photons (ADAP) have been studied in the case of positron annihilation in GaAs and GaP single crystals. Relative variations in defect accumulation and annealing under irradiation and subsequent isochronous annealing of the samples have been studied using variations in the basic parameters of the ADAP spectra. In both cases (GaAs and GaP), the variations in the ADAP spectral parameters as functions of the annealing temperature have a steplike character, which is interpreted as the formation of a certain type of defects with different annealing activation energies.

Modifications of the registration properties of charged particles in a CR-39 polymeric track detector induced by thermal annealing

The thermal annealing behavior of alpha and fission fragment tracks, following exposure pre- and post-annealing, in a high polymer material of poly allyl diglycol carbonate (PADC), a form of CR-39, has been investigated as a function of temperature and time. Isothermal and isochronal annealing experiments were carried out on CR-39 polymeric detectors exposed to a 252Cf source. The yields of fission fragment and surviving alpha tracks were measured as a function of annealing time and temperature, as was the variation of fission track diameter with annealing time. The bulk and track etch rates were measured using alpha and fission fragment track diameters and the bulk etch rate was also measured by the weight loss method. The activation energy of annealing was determined using two different models based on the experimental results. This paper presents novel information showing that the annealed CR-39 detectors were demonstrated to be highly sensitive to the fission fragments, but not to alpha particles.