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TT: Fachverband Tiefe Temperaturen

TT 16: 2D Materials I: Electronic Structure (joint session O/TT)

TT 16.2: Talk

Monday, March 18, 2024, 15:15–15:30, MA 005

Non-ambient Raman spectroscopy combined with ion bombardment — •André Maas, Joel Verlande, Leon Daniel, Lucia Skopinski, Lars Breuer, and Marika Schleberger — Universität Duisburg-Essen, Fakultät für Physik and CENIDE, Germany

Characterizing materials in non-ambient conditions poses a persistent challenge, particularly in understanding irradiation-induced defects and their effects on crystal structure and electronic/optoelectronic properties. While ambient conditions often saturate defects with adsorbates, investigating the influence of unsaturated defects remains crucial for a comprehensive understanding.

In the first part of this study, we focused on analyzing defect formation in CVD-grown WS₂ by irradiating it with low-energy Ar⁺ ions (E_kin≤ 500 eV) to create sulfur vacancies. Subsequent analysis via Raman and photoluminescence spectroscopy revealed insights into the nature of these defects. A custom-built cell was used enabling us to characterize the electrical and optical properties at a pressure of p=10⁻⁶ mbar, to study the effects of temperature (77 K to 600 K) and the presence of sulfur hexafluoride on the irradiated samples.

In a novel experiment, defects were induced in graphene using highly charged ions (Xe¹⁷⁺ - Xe⁴⁰⁺ at around E_kin=200 keV). In-situ optical measurements at ultra-high vacuum (p=10⁻⁹ mbar) allowed us to detect the influence of saturated defects on the properties of this important 2D material.

Keywords: WS2; Defects; Raman; Photoluminescence; Vacancies