Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 24: Graphene: Adsorption, Intercalation and Doping II (joint session O/TT)

TT 24.4: Talk

Monday, March 12, 2018, 17:30–17:45, MA 043

Advances in ultra-low energy ion implantation of low dimensional materials — •Hans Hofsäss and Manuel Auge — II. Physikalisches Institut, Universität Göttingen, Germany

Doping of 2D materials by ion implantation has unique requirements regarding ion energy, ion energy spread, ion beam optics, sample preparation and sample electrical conductivity. Efficient incorporation of low energy ions into 2D lattices requires energies well below 50 eV. We use a 30 keV mass selected ion beam, guided through differential pumping stages and homogenized by a beam sweep. The beam is then decelerated in a UHV-chamber down to energies as low as 10 eV onto an area of 1 cm² up to 2.5 cm². Up to now ion sources are available for B, C, N ,F, P, S, Mn, Se, W and Au ions. Ion sources for elements Al, Fe, As and rare earth elements are under development. The implanted areal concentration and elemental composition are verified with in-situ Auger spectroscopy and more quantitative with Rutherford backscattering by implanting into amorphous carbon films as test samples. The detection limit is below 1*10¹⁴ ions/cm² for heavier elements. Implanted B can be analyzed with the ¹¹B(p,2α)α nuclear reaction with a detection limit of about 1*10¹⁴ B/cm². Challenges for ULE ion implantation such as non-flat substrates, charging of substrates, cleaning of surfaces and lateral controlled implantation will be briefly discussed. Some examples for doped graphene and MoS₂ are presented