Model for radiation damage buildup in GaN

Titov, A.I.; Karaseov, P. A.; Kataev, A.Yu.; Azarov, Alexander; Kucheyev, S. O.

doi:10.1016/j.nimb.2011.12.029

Cited by 19 publications

(15 citation statements)

References 11 publications

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“…3). This clearly shows the high importance of the secondary defect formation processes in radiationinduced stable damage accumulation in GaN, as suggested in [47]. Fig.…”

Section: Resultssupporting

confidence: 64%

“…SAL formation indicates that the surface is a nucleation site for point defects. It was earlier shown that the lattice amorphization rate at the surface linearly increases with the amount of point defects coming to the amorphous/crystalline interface [47,48]. Overlapping of individual collision cascades formed by atoms comprising the PFn molecule locally increases cascade density at the sample surface and, in turn, increases the number of point defects produced by molecular ions in the surface vicinity.…”

Section: Resultsmentioning

confidence: 98%

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Single and molecular ion irradiation-induced effects in GaN: experiment and cumulative MD simulations

Karaseov

Karabeshkin

Titov

et al. 2017

J. Phys. D: Appl. Phys.

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An investigation of mechanisms of enhancement of irradiation-induced damage formation in GaN under molecular in comparison to monatomic ion bombardment is presented. Ionimplantation-induced effects in wurtzite GaN bombarded with 0.6 keV/amu F, P, PF2, and PF4 ions at room temperature are studied experimentally and by cumulative MD simulation in the correct irradiation conditions. In the low dose regime, damage formation is correlated with a reduction in photoluminescence decay time, whereas in the high dose regime, it is associated with the thickness of the amorphous layer formed at the sample surface. In all the cases studied, a switch to molecular ion irradiation from bombardment by its monatomic constituents enhances the damage accumulation rate. Implantation of heavy Ag ion, having approximately the same mass as the PF4 molecule, is less effective in surface damage formation, but leads to noticeably higher damage accumulation in the bulk.. The cumulative MD simulations do not reveal any significant difference in the total amount of both point defects and small defect clusters produced by light monatomic and molecular ions. On the other hand, increased production of large defect clusters by molecular PF4 ions is clearly seen in the vicinity of the surface. Ag ions produce almost the same number of small, but more large defect clusters compare to the others. This findings show that the enhancement of stable damage formation in GaN under molecular, as well as under heavy monatomic ion irradiation, can be related to the higher formation probabilityof large defect clusters.

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“…3). This clearly shows the high importance of the secondary defect formation processes in radiationinduced stable damage accumulation in GaN, as suggested in [47]. Fig.…”

Section: Resultssupporting

confidence: 64%

Section: Resultsmentioning

confidence: 98%

Single and molecular ion irradiation-induced effects in GaN: experiment and cumulative MD simulations

Karaseov

Karabeshkin

Titov

et al. 2017

J. Phys. D: Appl. Phys.

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“…Interestingly a similar mechanism has been put forward to explain a fluence dependent shift of a bulk damage peak in GaN [23]. Evidently, this process requires that the effective diffusion length of the mobile point defects is comparable to or higher than the distance between the defect generation region and the sample surface.…”

Section: Resultsmentioning

confidence: 78%

Dynamic defect annealing in wurtzite MgZnO implanted with Ar ions

Azarov

Wendler

et al. 2015

Nuclear Instruments and Methods in Physics Research Section B:

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“…Due to the close proximity of these collisions, a considerable amount of momentum is transferred to the surface lattice and the displaced atoms within the 7 nm spot could experience multiple impacts within a short period of time. This effect as well as lower cohesive energy between surface atoms relative to the bulk crystal increases the likelihood of ejection of surface atoms or those close to the surface and is believed to be responsible for the observed disorder in the top GaN surface. − The second layer was consistently found to have a lower lattice disorder, most likely, due to the channeling of Ga ions traveling parallel to ⟨0001⟩, which enhances the Ga ion travel range and reduces its sputtering rate …”

Section: Resultsmentioning

confidence: 99%

Observation and Impact of a “Surface Skin Effect” on Lateral Growth of Nanocrystals

et al. 2017

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We investigate the impact of a quasi-crystalline two-dimensional (2D) surface on the lateral epitaxy of one-dimensional (1D) nanocrystals. The quasi-2D surface was formed by locally conditioning a GaN crystalline lattice at and below surface using a low-dose focused Ga ion beam ranging from 9 to 354 ions/pulse. Short ion pulses/site are used to create the 2D arrays of sub-10-nm circular disks modulating the GaN lattice to a depth of about 30 nm. Impact of this localized lattice modulation was investigated on lateral epitaxy of 1D ZnO nanocrystal and electronic structure of formed heterojunctions. High resolution transmission electron microscopy (HRTEM) below the GaN surface reveals direct evidence of a “skin effect” that influences the surface epitaxy of low-dimensional nanocrystals. We define this effect as the crystallinity of the top 10 nm of the substrate that is found to be a key factor in occurrence of lateral epitaxy. HRTEM shows that lateral epitaxy stops, if the thin skin layer is disrupted. However, if the lattice structure of this layer rebounds, the lateral epitaxy occurs. Results indicate that, beyond the skin depth of about 10 nm, the disorder of the subsurface lattice does not impact the structure of the overgrown nanocrystals. These findings suggest the possibility of surface engineering for enabling spatially controlled modulation of the electronic structure of low-dimensional nanocrystals on a scalable fashion.

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Model for radiation damage buildup in GaN

Cited by 19 publications

References 11 publications

Single and molecular ion irradiation-induced effects in GaN: experiment and cumulative MD simulations

Single and molecular ion irradiation-induced effects in GaN: experiment and cumulative MD simulations

Dynamic defect annealing in wurtzite MgZnO implanted with Ar ions

Observation and Impact of a “Surface Skin Effect” on Lateral Growth of Nanocrystals

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