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- Herbig, Charlotte, et al.
(författare)
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Xe irradiation of graphene on Ir(111): From trapping to blistering
- 2015
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 92:8
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Tidskriftsartikel (refereegranskat)abstract
- Using x-ray photoelectron spectroscopy, thermal desorption spectroscopy, and scanning tunneling microscopy, we show that upon keV Xe+ irradiation of graphene on Ir(111), Xe atoms are trapped under the graphene. Upon annealing, aggregation of Xe leads to graphene bulges and blisters. The efficient trapping is an unexpected and remarkable phenomenon given the absence of chemical binding of Xe to Ir and to graphene, the weak interaction of a perfect graphene layer with Ir(111), as well as the substantial damage to graphene due to irradiation. By combining molecular dynamics simulations and density functional theory calculations with our experiments, we uncover the mechanism of trapping. We describe ways to avoid blister formation during graphene growth, and also demonstrate how ion implantation can be used to intentionally create blisters without introducing damage to the graphene layer. Our approach may provide a pathway to synthesize new materials at a substrate-2D material interface or to enable confined reactions at high pressures and temperatures.
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| 2. |
- Schroeder, Ulrike A., et al.
(författare)
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Etching of graphene on Ir(111) with molecular oxygen
- 2016
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223. ; 96, s. 320-331
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms for oxygen etching of graphene on Ir(111) are uncovered through a systematic variation of the graphene morphology - ranging from an impermeable graphene layer to graphene nanoflakes - and the application of complementary experimental methods, including scanning tunneling microscopy, X-ray photoelectron spectroscopy, and temperature programmed desorption. Associated with a strong variation in the onset temperature for etching, we find a fundamental difference in the onset of etching for an impermeable layer and for graphene flakes. For the impermeable graphene layer etching is shown to nucleate at graphene pentagon heptagon point defects through molecules impinging from the gas phase. For graphene flakes the nucleation problem is absent due to the existence of edges in contact with the metallic substrate. The substrate enables dissociative chemisorption of oxygen, which can then diffuse as atomic oxygen to the graphene edge. Our results show that intercalation of oxygen is neither a necessary condition nor of specific relevance for etching. Based on our analysis, a quantitative estimate for the activation energy and attempt frequency of the elementary etch process in flake etching on Ir(111) is provided. (C) 2015 Elsevier Ltd. All rights reserved.
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