| 1. |
- Azarov, Alexander, et al.
(författare)
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Defect annealing kinetics in ZnO implanted with Zn substituting elements : Zn interstitials and Li redistribution
- 2019
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Ingår i: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 125:7
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Tidskriftsartikel (refereegranskat)abstract
- It is known that the behavior of residual Li in ion implanted ZnO depends on the preferential localization of the implants, in particular, forming characteristic Li depleted or Li pile-up regions for Zn or O sublattice occupation of the implants due to the corresponding excess generation of Zn and O interstitials in accordance with the so-called "+1 model." However, the present study reveals that conditions for the radiation damage annealing introduce additional complexity into the interpretation of the Li redistribution trends. Specifically, four implants residing predominantly in the Zn-sublattice, but exhibiting different lattice recovery routes, were considered. Analyzing Li redistribution trends in these samples, it is clearly shown that Li behavior depends on the defect annealing kinetics which is a strong function of the implanted fluence and ion species. Thus, Li depleted and Li pile-up regions (or even combinations of the two) were observed and correlated with the defect evolution in the samples. It is discussed how the observed Li redistribution trends can be used for better understanding a thermal evolution of point defects in ZnO and, in particular, energetics and migration properties of Zn interstitials.
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| 2. |
- Azarov, Alexander, et al.
(författare)
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Dopant incorporation in thin strained Si layers implanted with Sb
- 2010
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 518:9, s. 2474-2477
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Tidskriftsartikel (refereegranskat)abstract
- The effect of tensile strain on Sb incorporation in Si and its activation during post-implantation annealing has been Studied by a combination of Rutherford backscattering/channeling spectrometry, secondary ion mass spectrometry. X-ray diffraction and 4-point probe measurements Our results show that, for Sb implanted samples a tensile strain has an important role for dopant behavior Particularly, increasing the tensile strain in the Si layer from 0 to 0 8% leads to an enhancement of the fraction of incorporated Sb atoms in substitutional sites already during implantation from similar to 7 to 30% Furthermore, 0 8% strain in antimony doped Si gives similar to 20% reduction in the sheet resistance in comparison to the unstrained sample.
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| 3. |
- Azarov, Alexander, et al.
(författare)
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Effect of collision cascade density on radiation damage in SiC
- 2009
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 267:8-9, s. 1247-1250
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Tidskriftsartikel (refereegranskat)abstract
- The damage accumulation in 6H-SiC bombarded at room temperature with 1.3 keV/amu atomic P+ ions and small cluster ions PFn+ (n = 2 and 4) have been studied by Rutherford backscattering spectrometry in channeling mode. Results show that collision cascade density strongly affects damage buildup in SiC. The cluster ion bombardment of SiC produces more stable defects both near the surface and in the region between the surface and bulk defect peaks than irradiation by atomic ions.
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| 4. |
- Azarov, Alexander, et al.
(författare)
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Extended defects in ZnO : Efficient sinks for point defects
- 2017
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 110:2
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Tidskriftsartikel (refereegranskat)abstract
- Dopant-defect reactions dominate the defect formation in mono-crystalline ZnO samples implanted with Ag and B ions. This is in contrast to most other ion species studied and results in an enhanced concentration of extended defects, such as stacking faults and defect clusters. Using a combination of B and Ag implants and diffusion of residual Li atoms as a tracer, we demonstrate that extended defects in ZnO act as efficient traps for highly mobile Zn interstitials. The results imply that dynamic annealing involving interaction of point defects with extended ones can play a key role in the disorder saturation observed for ZnO and other radiation-hard semiconductors implanted with high doses.
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| 5. |
- Azarov, Alexander, et al.
(författare)
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Optical activity and defect/dopant evolution in ZnO implanted with Er
- 2015
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Ingår i: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 118:12
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Tidskriftsartikel (refereegranskat)abstract
- The effects of annealing on the optical properties and defect/dopant evolution in wurtzite (0001) ZnO single crystals implanted with Er ions are studied using a combination of Rutherford backscattering/channeling spectrometry and photoluminescence measurements. The results suggest a lattice recovery behavior dependent on ion dose and involving formation/evolution of an anomalous multipeak defect distribution, thermal stability of optically active Er complexes, and Er outdiffusion. An intermediate defect band occurring between the surface and ion-induced defects in the bulk is stable up to 900 degrees C and has a photoluminescence signature around 420 nm well corresponding to Zn interstitials. The optical activity of the Er atoms reaches a maximum after annealing at 700 degrees C but is not directly associated to the ideal Zn site configuration, since the Er substitutional fraction is maximal already in the as-implanted state. In its turn, annealing at temperatures above 700 degrees C leads to dissociation of the optically active Er complexes with subsequent outdiffusion of Er accompanied by the efficient lattice recovery.
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| 6. |
- Ma, Quanbao, et al.
(författare)
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Boron-implanted 3C-SiC for intermediate band solar cells
- 2016
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Ingår i: Silicon Carbide and Related Materials 2015. ; , s. 291-294
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Konferensbidrag (refereegranskat)abstract
- Sublimation-grown 3C-SiC crystals were implanted with 2 atomic percent of boron ions at elevated temperature (400 °C) using multiple energies (100 to 575 keV) with a total dose of 8.5×1016 atoms/cm2. The samples were then annealed at 1400, 1500 and 1600 °C for 1h at each temperature. The buried boron box-like concentration profile can reach ~2×1021 cm-3 in the plateau region. The optical activity of the incorporated boron atoms was deduced from the evolution in absorption and emission spectra, indicating possible pathway for achieving an intermediate band behavior in boron doped 3C-SiC at sufficiently high dopant concentrations.
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| 7. |
- Ma, Quanbao, et al.
(författare)
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Characterization of B-Implanted 3C-SiC for Intermediate Band Solar Cells
- 2017
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Ingår i: Materials Science Forum. - : Trans Tech Publications. - 0255-5476 .- 1662-9752. ; 897, s. 299-302
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Tidskriftsartikel (refereegranskat)abstract
- Sublimation-grown 3C-SiC crystals were implanted with B ions at elevated temperature (400 °C) using multiple energies (100 to 575 keV) with a total dose of 1.3×1017 atoms/cm2 in order to form intermediate band (IB) in 3C-SiC. The samples were then annealed at 1400 °C for 60 min. An anomalous area in the center was observed in the PL emission pattern. The SIMS analysis indicated that the B concentration was the same both within and outside the anomalous area. The buried boron box-like concentration profile can reach ~3×1021 cm-3 in the plateau region. In the anomalous area a broad emission band (possible IB) emerges at around ~1.7-1.8 eV, which may be associated with B-precipitates having a sufficiently high density.
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| 8. |
- Olsen, Vegard S., et al.
(författare)
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Effects of Substrate and Post-Deposition Annealing on Structural and Optical Properties of (ZnO)(1-x)(GaN)x Films
- 2019
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Ingår i: Physica status solidi. B, Basic research. - : WILEY-V C H VERLAG GMBH. - 0370-1972 .- 1521-3951. ; 256:6
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Tidskriftsartikel (refereegranskat)abstract
- The structural and optical properties of magnetron sputtered thin films of (ZnO)(1-x)(GaN)(x) deposited on zinc oxide, sapphire, and silicon oxide are studied as a function of strain accumulation and postdeposition anneals at 600-800 degrees C. For the experimental conditions studied, we found that different amounts of tensile strain accumulated in the samples practically does not affect the strong bandbowing effect, that is, optical bandgap, observed in the asdeposited alloys. In its turn, postdeposition annealing results in a reduction of the tensile strain and dislocation density in the films, as measured by both X-ray diffraction and transmission electron microscopy, corroborating an increase in the crystal quality. In addition, the grain size is found to increase with annealing temperature, for example, mean values of 20 nm up to 50 nm were measured for the alloys with x=0.15. Meanwhile, the fullwidth at half maximum of the (0002) X-ray diffraction reflection increases with annealing temperature, but with only a small increase in bandgap energies for the x=0.15 sample. However, this observation was explained combining the experimental data and firstprinciples calculations based on density functional theory, showing that the increase in the amount of Ga-N bonds lowers the total energy of the system. As such, we conclude that the thermal treatments increase the Ga-N ordering, resulting in several contributions or a widening of the diffraction peaks.
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| 9. |
- Patricia, Carvalho, et al.
(författare)
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Boron-doping of cubic SiC for intermediate band solar cells: a scanning transmission electron microscopy study
- 2018
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Ingår i: SciPost Physics. - Amsterdam, Netherlands : SciPost Foundation. - 2542-4653. ; 5:3, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- Boron (B) has the potential for generating an intermediate band in cubic silicon carbide (3C-SiC), turning this material into a highly efficient absorber for single-junction solar cells. The formation of a delocalized band demands high concentration of the foreign element, but the precipitation behavior of B in the 3C polymorph of SiC is not well known. Here, probe-corrected scanning transmission electron microscopy and secondary-ion mass spectrometry are used to investigate precipitation mechanisms in B-implanted 3C-SiC as a function of temperature. Point-defect clustering was detected after annealing at 1273 K, while stacking faults, B-rich precipitates and dislocation networks developed in the 1573 - 1773 K range. The precipitates adopted the rhombohedral B13C2 structure and trapped B up to 1773 K. Above this temperature, higher solubility reduced precipitation and free B diffused out of the implantation layer. Dopant concentrations E19 at.cm-3 were achieved at 1873 K.
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| 10. |
- Usman, Mohammad, et al.
(författare)
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Annealing of ion implanted 4H-SiC in the temperature range of 100-800 degrees C analysed by ion beam techniques
- 2010
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 268:11-12, s. 2083-2085
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Tidskriftsartikel (refereegranskat)abstract
- Ion implantation induced damage formation and subsequent annealing in 4H-SiC in the temperature range of 100-800 degrees C has been investigated. Silicon Carbide was implanted at room temperature with 200 key Ar-40 ions with two implantation fluences of 4 x 10(14) and 2 x 10(15) ions/cm(2). The samples were characterized by Rutherford backscattering and nuclear reaction analysis techniques in channeling mode using 2.00 and 4.30 MeV He-4 ion beams for damage buildup and recovery in the Si and C sublattices, respectively. At low ion fluence, the restoration of the Si sublattice is evident already at 200 degrees C and a considerable annealing step occurs between 300 and 400 degrees C. Similar results have been obtained for the C sublattice using the nuclear resonance reaction for carbon, C-12(alpha,alpha)C-12 at 4.26 MeV. For samples implanted with the higher ion fluence, no significant recovery is observed at these temperatures. (C) 2010 Elsevier B.V. All rights reserved.
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