In-situ CVD grown WS2-MoS2 lateral heterostructure with alloyed Interface: Strong photoluminescence enhancement and high on-off ratio field effect transistors

The semiconducting 2D transition metal dichalcogenides (TMDs) have gained substantial attention, though the progress in their lateral heterostructures (HS) and in-situ growth for electronic and optoelectronic applications has been very limited. Herein, we report a single-step in-situ chemical vapor deposition growth of bilayer WS₂-MoS₂ lateral HS, which ensures a clean diffused interface between WS₂ and MoS_2, enabling efficient charge transport. The spatial Raman, photoluminescent (PL), and Auger mapping of in-situ WS₂-MoS₂ lateral HS shows a clear transition from pure WS₂ to pure MoS₂ region through a graded WS_(1-x)Mo_xS₂ alloy interface. The composition and the width of the alloy interface could be tuned by careful choice of the proportion of precursor materials and by tuning the growth parameters. Spatially resolved PL spectra and PL mapping reveal a strongly enhanced (more than one order of magnitude) PL intensity in the HS interface attributed to the strain-induced bandstructure modification in the alloyed interface. Interestingly, the alloyed interface in the lateral HS also dramatically improves the electronic properties, resulting in an on-off ratio of 10⁸ in the fabricated field effect transistor, which is two orders of magnitude higher than their individual counterpart. These results on lateral HS are significant, and they pave the way to synthesize other different HSs for future electronic devices and integrated circuits.