## 3 Results and Discussion
### LON on Other TMDCs  
The AFM-LON was also performed in other type of TMDCs in order to elucidate the unusual growth mechanism found for the TaS\({}_{2}\) and to extend the method for the fabrication of heterostructures for future applications. The selected TMDCs were: TaSe\({}_{2}\), NbSe\({}_{2}\), and NbS\({}_{2}\). As well as TaS\({}_{2}\), all of them exhibit a metallic behavior at room temperature and superconducting type II at low temperature. They were conveniently exfoliated from CVT crystals by micromechanical exfoliation with the technique above mentioned, and transferred on to freshly base-activated Si p-doped substrates. Each sample preparation was always done just before performing the LON experiment following the same procedure used for the TaS\({}_{2}\). After applying similar oxidation parameters in _dynamic-tip_ LON mode, rippled motifs similar to the concentric rings obtained in TaS\({}_{2}\) were also observed on NbS\({}_{2}\). However, for the case of selenide compounds (TaSe\({}_{2}\) and NbSe\({}_{2}\)), oxide motifs of a central spot surrounded by a single ring with a nipple shape were always produced. This kind of feature reminds of the oxide growth on silicon and on certain polymers caused by a nano-explosion followed by a shockwave (Figure 7) [30]. It is worthy to mention that by means of applying a voltage with an AFM tip on the semiconducting TMDCs MoS\({}_{2}\)[31] and WSe\({}_{2}\)[32], different types of structures have been achieved, that also resemble the  
Figure 6: **(a)** AFM topography image measured in contact mode of a TaS\({}_{2}\) flake; **(b)** CT-AFM resistance mapping of the same flake; **(c)** AFM topography image of TaS\({}_{2}\) thin flakes; **(d)** CT-AFM resistance mapping of the patterned flake shown in **(c)**. patterns presented in this work. However in both cases, authors highlight the non-oxide nature of the motifs, against the results observed by us that prove the oxide nature of the obtained patterns on above mentioned metallic TMDCs (i.e. : HF etching experiments and spectroscopic measurements in [15]). During the exfoliation process of NbS\({}_{2}\) crystals, it was observed that the characteristic TMDCs platelet-like flakes were mixed with needle-like stacks. From the transmission electron microscopy analysis of these needles, we could infer the rhombohedral phase 3R of the NbS\({}_{2}\) (for detailed characterization see the Supplementary Materials S1). The local oxidation of this new system gave rise to a unique case of dendritic oxide growth (Figure 8a,b). Instead of the expected rippled mounds, dendritic shaped oxides that formed a fractal pattern were obtained on the needle. A range of oxidation parameters were utilized to create different sizes although all of them appeared to have the dendritic structure. While applying less voltage and shorter time pulses, the formations obtained were more rounded and smaller in size (Figure 8c-1), very high voltages (>\(-\)30 V) applied during 100 ms or more, derived in an uncontrolled oxide branched formation that grew several microns all over the surface until reaching the limits of the needle (Figure 8c-2). As observed for the rippling formations, the dendritic oxides always stopped at the edges of the crystal. The experiment was repeated in different needle-like stacks of 3R-NbS\({}_{2}\) and always a dendritic growth was obtained (Figure 8d-f). The dendrites have a central circular spot just right below the site were the AFM tip makes the discharge and then, it seems to evolve through avalanches like the ripple formations of the rest of the TMDCs studied. This anomalous structure could be due to an oxidation process taking place across the planes in the needle-like exfoliated crystals. Etching experiments were carried out to ascertain the 3D nature of this type of oxide formations. As can be seen in Figure 8f, the etching reveals a 3D pattern that grew deep inside the 3R-NbS\({}_{2}\). In this case, the 50% of the oxide grows above the substrate baseline.