Spectroscopic properties of thulium-doped tin disulfide synthesized under high pressure

The development of layered semiconductor doping and functionalization techniques is important for van der Waals heterostructure applications. Rare-earth impurities are of interest due to their ability to modify the optical, magnetic, and conductive properties of the semiconductor matrix. In this study, Tm-doped SnS2 powders (SnS2:Tm) with optically active rare-earth centers were synthesized under pressures up to 8–9 GPa and temperatures up to 1600 °C. The synthesized powders consisted of platy particles containing Sn, S, and Tm. Powder X-ray diffraction and Raman spectroscopy confirmed the crystallization of SnS2:Tm with lattice parameters and phonon modes close to those of undoped hexagonal SnS2. Photoluminescent measurements of SnS2:Tm exfoliated flakes revealed sharp emission lines from intra-center transitions 3F2,3 → 3H6 and 3H4 → 3H6 of Tm3+. The Stark splitting of these luminescence lines reflects the local D3d crystal-field environment of Tm3+ ions. The results obtained demonstrate that 2H-transition metal dichalcogenide lattices can serve as a matrix for rare-earth ions, combining a wide variety of structural and electrical properties of 2D materials with well-studied optical transitions in lanthanide ions.