Atomically-thin films of transition metal dichalcogenides (TMDCs), such as MoX₂ and WX₂ (X=S, Se), are semiconductors with thickness dependent optoelectronic properties. They have been used, in combination with other 2D materials such as graphene and boron nitride, to produce van der Waals heterostructure devices [1]. Rare earth (RE) ion doping is an approach to potentially add important functionality to both dielectric and semiconductor materials. The 4f shells within RE ions are shielded from the environment by the outer shell resulting in long excited state and spin lifetimes. Thus, RE-doped materials are widely used as optical gain media [2], and are being developed as a platform for spin qubits [3].

 

In this work, the synthesis of rare earth doped MoS_2­ powders and films by the co-pyrolysis of molecular precursors was studied. Mo-, Pr-, Er- and Nd- diethyldithiocarbamato complexes were synthesised and characterized by Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), elemental analysis and mass spectrometry. These precursors were used to form both powders and thin films of Pr,-doped, Er-doped, Nd-doped and undoped MoS₂, which were characterized by energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. SEM and EDX spatial mapping data shows that the Pr-, Nd and Er dopants are distributed homogeneously at the microscale. The XRD data shows that the 2H polymorph of MoS₂ was formed in each case.  Raman spectroscopy was used to investigate the effect of including the rare earth ions on the strain and electronic doping of the powders.

 

References.[DB1] 

1.           Kuc, A., T. Heine, and A. Kis, Electronic properties of transition-metal dichalcogenides. MRS bulletin, 2015. 40(7): p. 577-584.

2.           Chen, X., T. Sun, and F. Wang, Lanthanide‐Based Luminescent Materials for Waveguide and Lasing. Chemistry, an Asian journal, 2020. 15(1): p. 21-33.

3.           Aromí, G. and O. Roubeau, Chapter 309 - Lanthanide molecules for spin-based quantum technologies, in Handbook on the Physics and Chemistry of Rare Earths, J.-C.G. Bünzli and V.K. Pecharsky, Editors. 2019, Elsevier. p. 1-54.