Helium ion implantation-induced defects in silicon probed with variable-energy positrons

Fujinami, Masanori; Miyagoe, T.; Sawada, Tsuguo; Suzuki, Ryoichi; Ohdaira, Toshiyuki; Akahane, Takashi

doi:10.1103/physrevb.68.165332

Cited by 11 publications

(11 citation statements)

References 22 publications

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“…During annealing at 450°C, or 500°C, Kr conceivably could diffuse and decorate vacancies, although the temperature appears low compared to the 300°C necessary for making V 2 -He complexes 34 and ϳ800°C for making bubbles after Ne implantation. 35 the whole of the damaged layer, which is at least two orders of magnitude less than the vacancy concentration.…”

Section: Samplementioning

confidence: 95%

Annealing of electron-, proton-, and ion-produced vacancies in Si

et al. 2006

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Positron lifetime and Doppler measurements were performed on float-zone-refined and variously doped Czochralski-grown Si. The samples were irradiated by various particles ͑e − , p, Kr͒ with energies between 2 MeV and 245 MeV. Electron or proton irradiation gave rise to divacancies, whereas the damage from ion implantation ͑Kr͒ was mainly in the form of four-vacancy clusters, with only a small fraction of vacancies in the form of divacancies. In the case of impurity-lean Si, detailed isothermal annealing at various temperatures between 125°C and 500°C showed that after an initial fast decrease in divacancy concentration, a much slower process of vacancy agglomeration took place. At 450°C agglomeration steadily progressed even after 30 h of annealing at which point the average cluster size corresponded to ten monovacancies. In impurity-rich Si, containing oxygen and dopants, there is nearly no initial decrease in vacancy concentration, and isothermal and isochronal annealings showed that vacancy agglomeration was also nearly absent. Doppler data showed that vacancy-dopant complexes slowly acquired oxygen as annealing progressed, and these complexes survived annealing at 500°C for many hours. Measurements between 8 K and 530 K on samples containing divacancies, or larger clusters, showed a temperature dependence of the positron trapping rate that cannot be explained by the clusters being negatively charged, but can be explained if neutral clusters have a weakly bound positron state which at low temperatures makes trapping more efficient. Generally, the present positron experiments have given an indication for the type of defects that survive annealing at temperatures where electron paramagnetic resonance and infrared spectroscopy yield little useful information.

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Section: Samplementioning

confidence: 95%

Annealing of electron-, proton-, and ion-produced vacancies in Si

et al. 2006

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“…These results were confirmed by PALS measurements. 20 He, like H, was found to be able to fully saturate open volumes, moreover He in Si tends to agglomerate forming bubbles with very high internal pressure. 2 Positrons were found not to be trapped into bubbles or completely filled open volumes.…”

Section: Introductionmentioning

confidence: 96%

“…[10][11][12] The phenomena that cause the bubbles and cavities formation are several and they involve the implanted species as well as vacancies, interstitials, impurities, and dopants. 2 Depth profiling positron annihilation spectroscopy ͑DP-PAS͒ was successfully used to study the open volume defects in H [13][14][15] and He [16][17][18][19][20] implanted crystalline silicon ͑c-Si͒. DP-PAS is a powerful nondestructive tool for the characterization of the open volume defects from vacancies to nanovoids.…”

Section: Introductionmentioning

confidence: 99%

Single-crystal silicon coimplanted by helium and hydrogen: Evolution of decorated vacancylike defects with thermal treatments

et al. 2006

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Si p-type ͑100͒ samples were coimplanted at room temperature with He + ions at 30 keV with a dose of 1 ϫ 10 16 ions/ cm 2 and successively with H + ions at 24 keV with a dose of 1 ϫ 10 16 ions/ cm 2 . A series of samples was thermally treated for 2 h from 100 to 900°C at 100°C steps to study the evolution of pointlike and extended defects by two complementary techniques: positron Doppler broadening spectroscopy and transmission electron microscopy. Depth profiling the samples with a positron beam led to the identification of five different traps and the evolution of their profile distributions with thermal treatments. The positron traps were identified as decorated vacancy clusters of different sizes. Their decoration by implanted ions and in some case by oxygen was probed by coincidence Doppler broadening spectroscopy. Up to 300°C annealing temperature positrons probe three distributions of different decorated defects covering regions of the sample down to 400-450 nm. Starting from 300°C annealing temperature no defects were revealed by positrons in the region next to the peak of the implanted ions distributions positioned around 280 nm, where extended defects are expected; this indicates complete filling of the defects by H and He. From 300 to 600°C decorated vacancy clusters of different sizes appear progressively in the region below 280 nm, with a distribution moving deeper into the sample. Comparison with previous measurements on He-implanted samples points out the chemical action of H. Hydrogen atoms interact with the previous damage by He, producing more stabilized vacancylike defects distributed through the damage region of the sample. Electron microscopy shows the transformation of the extended defects from platelets to blisters and cavities.

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“…34 Positron life and Doppler measurements have shown the presence of divacancy in He or Si irradiated Si at room temperature. 35,36 While the He and Si implantations were performed at 77 K in our experiment, the implanted samples were warmed up to room temperature before channeling analysis and the subsequent irradiation. Since both isolated vacancies and interstitials are quite mobile at room temperature, the defects remaining prior to proton irradiation are most probably in the form of divacancy, di-interstitial or larger clusters and extended defects in He and Si implanted silicon.…”

Section: -4mentioning

confidence: 99%

Evolution of implantation induced damage under further ion irradiation: Influence of damage type

Wang

Nastasi

et al. 2009

Journal of Applied Physics

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The evolution of damage in silicon formed by H, He, and Si ion implantations under further ion irradiation, where the ion energy is primarily deposited into electronic excitation, has been studied at 77 K and at room temperature. For damage introduced by He or Si ion implantation, which primarily consists of vacancy and interstitial type defects, a subsequent irradiation with 110 keV protons at room temperature results in a decrease in ion channeling direct backscattering yield, while no change is observed when the irradiation is carried out at 77 K. In contrast, H ion implantation damage, which mainly consists of H-stabilized defects, is observed to increase under the same following on 110 keV proton irradiation at both room temperature and 77 K. The differences in damage evolutions can be used to construct a coherent picture of how energy deposited into electronic processes affects defect dissociation, migration, and reconstruction and the final damage morphology.

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Helium ion implantation-induced defects in silicon probed with variable-energy positrons

Cited by 11 publications

References 22 publications

Annealing of electron-, proton-, and ion-produced vacancies in Si

Annealing of electron-, proton-, and ion-produced vacancies in Si

Single-crystal silicon coimplanted by helium and hydrogen: Evolution of decorated vacancylike defects with thermal treatments

Evolution of implantation induced damage under further ion irradiation: Influence of damage type

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