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1.
Thermally stimulated current (TSC) measurements performed in the 100 K–400 K temperature range on Bi4Ti3O12 (BiT) thin films annealed at 550 °C and 700 °C had revealed two trapping levels having activation energies of 0.55 eV and 0.6 eV. The total trap concentration was estimated at 1015 cm−3 for the samples annealed at 550 °C and 3×1015 cm−3 for a 700 °C annealing and the trap capture cross-section was estimated about 10−18 cm2. From the temperature dependence of the dark current in the temperature range 20 °C–120 °C the conduction mechanism activation energy was found to be about 0.956–0.978 eV. The electrical conductivity depends not only on the sample annealing temperature but also whether the measurement is performed in vacuum or air. The results on the dark conductivity are discussed considering the influence of oxygen atoms and oxygen vacancies. Received: 28 January 1998 / Accepted: 8 January 1999 / Published online: 5 May 1999  相似文献   

2.
Abstract

The annealing behaviour of 80 keV room temperature arsenic implants in silicon below the amorphization dose has been studied by comparing the physical profile and the electrical profiles following different isochronal anneals.

It is shown that the electrically active fraction, which is about 0.4 after 30 min annealing at 600°C, increases continuously until 100% electrical activation of the arsenic ions is reached at about 900°C.

The activation energy for the annealing process has been found equal to 0.4 eV. A tentative interpretation of the mechanism involved is given.

From the analysis of the physical profiles obtained after isochronal annealing, an effective diffusion coefficient at 900°C equal to 5 × 10?16 cm2 s?1 has been calculated.  相似文献   

3.
GaP(001) cleaned by argon-ion bombardment and annealed at 500°C showed the Ga-stabilized GaP(001)(4 × 2) structure. Only treatment in 10?5 Torr PH3 at 500°C gave the P-stabilized GaP(001)(1 × 2) structure. The AES peak ratio PGa is 2 for the (4 × 2) and 3.5 for the (1 × 2) structure. Cs adsorbs with a sticking probability of unity up to 5 × 1014 Cs atoms cm?2 and a lower one at higher coverages. The photoemission measured with uv light of 3660 Å showed a maximum at the coverage of 5 × 1014 atoms cm?2. Cs adsorbs amorphously at room temperature, but heat treatment gives ordered structures, which are thought to be reconstructed GaP(001) structures induced by Cs. The LEED patterns showed the GaP(001)(1 × 2) Cs structure formed at 180°C for 10 h with a Cs coverage of 5 × 1014 atoms cm?2, the GaP(001)(1 × 4) Cs formed at 210°C for 10 hours with a Cs coverage of 2.7 × 1014 atoms cm?2, the GaP(001)(7 × 1) and the high temperature GaP(001)(1 × 4), the latter two with very low Cs content. Desorption measurements show three stability regions: (a) between 25–150°C for coverages greater than 5 × 1014 atoms cm?2, and an activation energy of 1.2 eV; (b) between 180–200°C with a coverage of 5 × 1014 atoms cm?2, and an activation energy of 1.8 eV; (c) between 210–400°C with a coverage of 2.7 × 1014 atoms cm?2, and an activation energy of 2.5 eV.  相似文献   

4.
Room temperature ferromagnetism was observed in Cr-implanted ZnO nanowires annealed at 500, 600, and 700 °C. The implantation dose for Cr ions was 1×1016 cm?2, while the implantation energies were 100 keV. Except for ZnO (100), (002), and (200) orientations, no extra diffraction peaks from Cr-related secondary phase or impurities were observed. With the increasing of annealing temperatures, the intensity of the peaks increased while the FWHM values decreased. The Cr 2p1/2 and 2p3/2 peaks, with a binding energy difference of 10.6 eV, appear at 586.3 and 575.7 eV, can be attributed to Cr3+ in ZnO nanowires. For the Cr-implanted ZnO nanowires without annealing, the band energy emission disappears and the defect related emission with wavelength of 500–700 nm dominates, which can be attributed to defects introduced by implantation. Cr-implanted ZnO nanowires annealed at 500 °C show a saturation magnetization value of over 11.4×10?5 emu and a positive coercive field of 67 Oe. The origin of ferromagnetism behavior can be explained on the basis of electrons and defects that form bound magnetic polarons, which overlap to create a spin-split impurity band.  相似文献   

5.
With increasing annealing temperature (Tanneal), the magnitude of the electric fields for the antiferroelectric‐to‐ferro‐electric (EAF) and ferroelectric‐to‐antiferroelectric (EFA) transition of a 9.2 nm thick Hf0.3Zr0.7O2 film decreased. The energy storage densities of the Hf0.3Zr0.7O2 films crystallized at 400 °C, 500 °C, and 600 °C were as large as 42.2 J/cm3, 40.4 J/cm3, and 28.3 J/cm3, respectively, at the electric field of 4.35 MV/cm. The maximum dielectric constant of the Hf0.3Zr0.7O2 film crystallized at 600 °C was the largest (~46) as it had the smallest EAF and EFA, whereas the leakage current density of the film crystallized at 400 °C was the smallest. The 400 °C of Tanneal was the optimum condition for energy storage application. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)  相似文献   

6.
Hall effect and electrical conductivity measurements of defect annealing in 1 ohm-cm n-type and 2 ohm-cm p-type silicon were made following neutron irradiation at ~50°C. Measurements were also made following 400-keV B11 ion implantation into a 100 ohm-cm n-type Si substrate. As the neutron fluence is increased the electrical effects of the damage eventually outweigh those of the chemical dopants, and further changes in the electrical properties become small. Conversely, significant electrical recovery upon annealing begins only when the electrical effects of the remaining damage become comparable to those of the chemical dopants. This condition will occur at higher anneal temperatures for higher fluence irradiations. The neutron fluence dependence of the damage and the annealing is interpreted in terms of the neutron energy per cm3. E, spent in atomic processes divided by the number/cm3, N, of electrically active dopants. When E/N ≤ 0.5 keV the electrical measurements show that the predominant defect annealing occurs below 400°C. However, when E/N > 0.5 keV electrical measurements emphasize the annealing at temperatures > 400°C. After 500°C annealing, energy levels in neutron damaged Si are observed at Ev +0.1 and Ev +0.15 eV in p-type and at Ec -0.33 eV in n-type Si. Application of the E/N criteria to room temperature implant-doped Si predicts that the electrical effects will be dominated by lattice damage even if all the implanted ions are substitutional.  相似文献   

7.
The fundamental absorption edge of evaporated WO3 films is investigated. The optical gap of the virgin film is estimated to be 3.41 eV at room temperature and it decreases with increase of annealing temperature up to 200°C. Annealing at 300°C leads to change in the spectral shape, which is caused by crystallization. For the films annealed at 200°C, temperature coefficient of the optical gap is estimated to be ?2×10?4 eV/K and the slope of Urbach's tail is found to be independent of measuring temperature up to 200°C. With electrolytic coloration, shift of the optical gap toward higher energy is observed. Magnitude of this shift is estimated to be 0.05 eV at the color center concentration of 7.5×1021 cm?3 when H+ electrolyte is used. If Li+ electrolyte is used, the magnitude of this shift is about three times larger than in the case of H+ electrolyte. This fact is interpreted by a small change in the host matrix structure owing to the injection of proton or Li+ during coloration.  相似文献   

8.
The fundamental absorption edge of evaporated WO3 films is investigated. The optical gap of the virgin film is estimated to be 3.41 eV at room temperature and it decreases with increase of annealing temperature up to 200°C. Annealing at 300°C leads to change in the spectral shape, which is caused by crystallization. For the films annealed at 200°C, temperature coefficient of the optical gap is estimated to be −2×10−4 eV/K and the slope of Urbach's tail is found to be independent of measuring temperature up to 200°C. With electrolytic coloration, shift of the optical gap toward higher energy is observed. Magnitude of this shift is estimated to be 0.05 eV at the color center concentration of 7.5×1021 cm−3 when H+ electrolyte is used. If Li+ electrolyte is used, the magnitude of this shift is about three times larger than in the case of H+ electrolyte. This fact is interpreted by a small change in the host matrix structure owing to the injection of proton or Li+ during coloration.  相似文献   

9.
The lattice damage of silicon produced by ion implantation at extremely high current density of 0.8 A/cm2 (2.5᎒18 cm-2 s-1) was investigated. In a focused ion beam system, implantation was carried out with 70 keV Co ions, fluences of 1.2᎒16 cm-2 and 6.7᎒15 cm-2 into Si (111) at room temperature and elevated temperatures between 355 °C and 400 °C. Radiation damage measurements were performed by Rutherford backscattering/channeling spectroscopy and micro-Raman analysis. The radiation damage was studied as a function of pixel dwell-time and implantation temperature. The critical temperature for amorphization increases with current density. Although the fluence of the focused ion implantation was constant, crystalline layers were obtained for short and amorphous layers for long pixel dwell-times. The critical dwell-time of crystalline/amorphous transition increases with implantation temperature. From the results a typical time for defect annealing of 10-5 s at 400 °C and an activation energy of (2.5ǂ.6) eV were deduced.  相似文献   

10.
The conductivity and thermal stability of NH+4, H+(H2O)nβ″ and ion-rich β-alumina single crystals have been measured by the complex impedance method in the 25–700°C temperature range. Both structures have similar properties, but ion-rich β-alumina shows a higher stability and a lower activation energy (β: 0.18 eV, β″ 0.24 eV below 400°C and 250°C respectively). The room temperature conductivity is about 3×10-5ω-1cm-1. The conducting properties and mechanisms are discussed and compared to other protonic or ionic conductors.  相似文献   

11.
We have investigated the annealing behaviors of point defects and their influence on the electrical degradation and recovery of heavily neutron irradiated silicon. It is found that high concentrations of divacancy (V2) and vacancy-oxygen (VO) complexes are introduced in heavily irradiated silicon, which is responsible for the enhanced carrier recombination and therefore the observed drastic decrease of carrier lifetime. While the dopants deactivation from vacancy-phosphorus (VP) complexes and carrier compensation from VO and V2 complexes result in the remarkable increase of resistivity. After post-irradiation isochronal annealing at 200–400°C the carrier lifetime and resistivity exhibit insignificant changes, which is attributed to the transformation of V2 and VO complexes into [VO?+?Oi], V2O, V3O complexes at 200–300°C and the possible formation of VP-O complexes at 400°C. While the heat treatments at elevated temperatures (>400°C) result in the elimination of the majority of electrically active VmOn and the possible VP-O complexes, and therefore the carrier lifetime and resistivity of silicon begin to recover at 500°C and 650°C, respectively. However, the recovery of carrier lifetime is incomplete, which is due to the enhanced carrier-recombination from the survival defects with deep levels at EC ? 0.24?eV and EC ? 0.44?eV during annealing.  相似文献   

12.
We have studied the effects of thermal annealing on the electrical properties of InAs/InP self-assembled quantum dots (QDs) using deep level transient spectroscopy (DLTS). It was found from the DLTS measurements that the activation energy of the QD signal varied from 0.47 to 0.60 eV and the emission cross section changed from 1.01×10−15 to 9.63×10−14 cm2 when the annealing temperature increased up to 700 °C. As a result of the thermal annealing process at the temperature ranging from 500 to 600 °C, the higher activation energy and the larger emission cross section of the QD related signal were observed for the annealed samples compared to those for the as-grown sample. On the basis of the capture barrier height for the QDs structure being lowered from 0.24 to 0.06 eV at the annealing temperature of 700 °C, thermal damage was considered as the reason. The appropriate annealing process can provide a clue for the engineering of the energy levels in the self-assembled QD structures.  相似文献   

13.
14 /cm2 dose of As ions followed by both isochronal and isothermal annealing. The elementary defects generated first during solid-phase epitaxial recovery of implantation-induced amorphous layers at temperatures of 550 °C and/or 600 °C are {311} defects 2–3 nm long. They are considered to be transformed into {111} and {100} defects after annealing at temperatures higher than 750 °C. These secondary defects show the opposite annealing behavior to the dissolution and growth by the difference of their depth positions at 800 °C. This phenomenon is explained by the diffusion of self-interstitials contained in defects. With regard to the formation and dissolution of defects, there is no significant difference between the effects of rapid thermal annealing (950 °C for 10 s) and furnace annealing (800 °C for 10 min). Received: 14 November 1997/Accepted: 16 November 1997  相似文献   

14.
The formation of nanoparticles in СZn-Si(100) implanted with 64Zn+ ions using a dose of 5 × 1016 cm–2 and an energy of 50 keV at room temperature with subsequent thermal processing in oxygen at temperatures ranging from 400 to 900°C is studied. The surface topology is investigated with scanning electron (in the secondary emission mode) and atomic force microscopes. The structure and composition of the near-surface silicon layer are examined using a high-resolution transmission electronic microscope fitted with a device for energy dispersive microanalysis. An amorphized near-surface Si layer up to 130 nm thick forms when zinc is implanted. Amorphous zinc nanoparticles with an average size of 4 nm are observed in this layer. A damaged silicon layer 50 nm thick also forms due to radiation defects. The metallic zinc phase is found in the sample after low-temperature annealing in the range of 400–600°C. When the annealing temperature is raised to 700°C, zinc oxide ZnO phase can form in the near-surface layer. The complex ZnO · Zn2SiO4 phase presumably emerges at temperatures of 800°C or higher, and zinc-containing nanoparticles with lateral sizes of 20–50 nm form on the sample’s surface.  相似文献   

15.
Both electrical and optical activation studies of Si-implanted Al0.18Ga0.82N have been made as a function of anneal time and anneal temperature to obtain maximum possible electrical activation efficiency. Silicon ions were implanted at 200 keV with doses of 5×1014 and 1×1015 cm−2, and the samples were annealed from 1100 to 1250 °C for 5-25 min with a 500 Å thick AlN cap in a nitrogen environment. The electrical activation efficiency and Hall mobility increase with anneal time and anneal temperature. Nearly 100 and 95% electrical activation efficiencies were obtained for Si-implanted Al0.18Ga0.82N with doses of 5×1014 and 1×1015 cm−2 and annealing at 1250 and 1200 °C for 25 min, respectively. The photoluminescence measurements show an excellent implantation damage recovery after annealing at these optimum anneal conditions, showing a strong near band emission. These optical results correlate well with the electrical results.  相似文献   

16.
A study was undertaken on a Ti–25Nb–3Mo–3Zr–2Sn alloy using differential scanning calorimetry (DSC) in order to improve understanding of the precipitation reactions occurring during aging heat treatments. The investigation showed that isothermal ω phase can be formed in the cast and solution treated alloy at low aging temperatures. An exothermic peak in the temperature range of 300 to 400°C was detected for precipitation of the ω phase, with approximate activation energy of 176 kJ/mol. The ω phase begins to dissolve at temperatures around 400°C and precipitation of the α phase is favoured at higher temperatures between 400°C and 600°C. An exothermic peak with activation energy of 197 kJ/mol was measured for precipitation of the α phase. Deformation resulting in the formation of the stress induced α″ phase altered the DSC heating profile for the solution treated alloy. The exothermic peak associated with precipitation of the ω phase was not detected during heating of the deformed material and increased endothermic heating associated with recovery and recrystallisation was observed.  相似文献   

17.
A thin poly(ethylmethacrylate) (PEMA) layer is deposited on n-InP as an interlayer for electronic modification of Au/n-InP Schottky structure. The electrical properties of Au/PEMA/n-InP Schottky diode have been investigated by current–voltage (IV) and capacitance–voltage (CV) measurements at different annealing temperatures. Experimental results show that Au/PEMA/n-InP structure exhibit a good rectifying behavior. An effective barrier height as high as 0.83 eV (IV) and 1.09 eV (CV) is achieved for the Au/PEMA/n-InP Schottky structure after annealing at 150 °C compared to the as-deposited and annealed at 100 and 200 °C. Modified Norde's functions and Cheung method are also employed to calculate the barrier height, series resistance and ideality factors. Results show that the barrier height increases upon annealing at 150 °C and then slightly decreases after annealing at 200 °C. The PEMA layer increases the effective barrier height of the structure as this layer creates a physical barrier between the Au metal and the n-InP. Terman's method is used to determine the interface state density and it is found to be 5.141 × 1012 and 4.660 × 1012 cm?2 eV?1 for the as-deposited and 200 °C annealed Au/PEMA/n-InP Schottky diodes. Finally, it is observed that the Schottky diode parameters change with increasing annealing temperature.  相似文献   

18.
《Solid State Ionics》1988,26(3):229-235
Amorphous LiZr2(PO4)3 has been prepared at room temperature starting from aqueous solutions of ZrOCl2, H3PO4, and LiOH and then crystallized by heating at temperatures between 600 and 900°C. The material obtained at 900°C has been characterized by X-ray powder diffractometry, DSC analysis, and ac conductivity. It is monoclinic from 20 up to about 300°C and orthorhombic at higher temperatures. A change in the activation energy for conduction (from 0.79 to 0.43 eV) and a weak endothermic effect (0.9–1.7 cal/g) are associated with the phase transition. The ac conductivity of sintered pellets is, on average, 7×10−4 S cm−1 at 300°C.  相似文献   

19.
Abstract

In this paper we report the results of a study of the annealing properties of the ionized defect density associated with the damage created in the silicon lattice by implantation of 2.8 MeV protons at room temperature. In particular, the annealing of damage created by implanting to a level of 4.43 × 1012 protons/cm2 is reported. The resulting isochronal annealing curve covered the temperature range from 70°C to 460°C. Two major annealing stages are discussed, one a broad stage between 70°C to 200°C and the other an abrupt annealing stage between 440°C to 460°C. Between the temperature range 200°C to 440°C the number of ionized defects remained relatively constant. Above 460°C no detectable effects of the proton implantation remained.  相似文献   

20.
It has been shown that post-radiation annealing of LiF crystals irradiated by high neutron fluences (1015–1018 neutrons/cm2) at comparative low temperatures (300–400°C) creates optimal conditions for single-system dislocation glide, which favors a complete recovery of the plasticity with conservation of a significant fraction of radiation hardening.  相似文献   

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