Dr. Jörg Malindretos

Physical Institute (Solid state physics and nanostructures), University of Göttingen

Molecular Beam Epitaxy of 2H-TaS₂ few-layers on GaN(0001) 

C. Hilbrunner, J. Malindretos, and A. Rizzi - IV. Physikalisches Institut, Georg-August-Universität Göttingen

2H-TaS₂ few layers have been grown epitaxially onto GaN(0001). A high substrate growth temperature of 825 ºC induces best structural properties of the overlayer, as revealed by insitu electron diffraction (RHEED and LEED). The 2D-overlayer grows unstrained right after deposition of a monolayer. However, evidence of pits at the interface is provided by scanning transmission electron microscopy, most probably due to GaN thermal decomposition at the high growth temperature. In-situ x-ray photoemission spectroscopy shows core level shifts that are consistently related to electron transfer from the n-GaN(0001) to the 2H-TaS₂ epitaxial layer as well as the formation of a high concentration of nitrogen vacancies close to the interface. Further, no chemical reaction at the interface between the substrate and the grown TaS₂ overlayer is deduced from XPS, which corroborates the possibility of integration of 2D 2H-TaS₂ with an important 3D semiconducting material like GaN.

Figure 1: AFM topography measurements (1 µm × 1 µm) of (a) the GaN substrate, (b) after growth of 2H-TaS₂ (6 ML) at T_g = 620 ºC and (c) after growth at T_g = 825 ºC. The scale bar length is 100 nm.
Corresponding LEED patterns measured at a beam energy of 100 eV are reported in the insets. The slight rotation of the LEED pattern in (c) is due to a rotation of the sample holder.

[1]  C. Hilbrunner, T. Meyer, J. Malindretos and A. Rizzi: 2D Mater. 12, 045027 (2025), doi: 10.1088/2053-1583/ae1516.