Strain‐dependent electronic and optical properties are one of the most appealing features of 2D semiconductors, like monolayer (1L) MoS ₂ . However, measuring and controlling the homogeneity of strain within the channel is crucial for next‐generation MoS ₂ field‐effect transistors (FETs). This article reports a multiscale investigation of backgated FETs fabricated using large‐area 1L MoS ₂ flakes grown by liquid‐precursor‐intermediated chemical vapor deposition on SiO ₂ /Si substrates. The devices exhibit very attractive properties for ultra‐low power applications, such as an I _on / I _off > 10 ⁶ and a normally off electrical behavior. The combination of temperature‐dependent analyses of the FET transfer characteristics and nanoscale resolution potential mapping by Kelvin probe force microscopy shows a fully depleted MoS ₂ channel at V _G = 0 and an effective Schottky barrier Φ _B,FB = 0.21 eV at flatband voltage V _FB = 17.9 V. An inhomogeneous tensile strain ( ε ) distribution along the channel length is revealed by micro‐Raman and photoluminescence (PL) mapping, with a reduced ε and blue‐shifted PL energy close to the Ni/Au source/drain contacts, suggesting a biaxial compression of 1L MoS ₂ induced by metal deposition. The implications of these observations on the effective mass m _eff variation along the channel and the current injection from source/drain contacts have been discussed in the perspective of future ultra‐scaled‐devices applications.

This study introduces a straightforward technique for edge engineering in MoS₂ flakes through chemically induced nano‐folding. By utilizing a buffered oxide etchant solution, precise detachment is achieved from the substrate and controlled folding/rolling of MoS₂ flakes, resulting in the creation of additional active edges up to 100 times thicker than the original flake. The model material, MoS₂ grown on silicon substrates via chemical vapor deposition, undergoes a dramatic transformation in morphology. This transformation is driven by partial detachment from the substrate, followed by bending and folding of the flake boundaries, which generates well‐defined additional edges. The impact of edge thickening is demonstrated on fundamental characteristics such as work function, crystallinity, and catalytic properties. Notably, the findings demonstrate that the engineered edges significantly enhance the electrocatalytic activity of MoS₂ in hydrogen evolution reactions. This highlights the potential of this method to substantially improve the performance of low‐dimensional materials.

Atomically thin molybdenum disulfide (MoS₂) is a two-dimensional semiconductor with versatile applications. The recent adoption of liquid molybdenum precursors in chemical vapor deposition has contributed significantly to the reproducible wafer-scale synthesis of MoS₂ monolayer and few-layer films. In this work, we study the effects of the carrier gas flow rate on the properties of two-dimensional molybdenum disulfide grown by liquid-precursor-intermediate chemical vapor deposition on SiO₂/Si substrates. We characterized the samples using Optical Microscopy, Scanning Electron Microscopy, Raman spectroscopy, and Photoluminescence spectroscopy. We analyzed samples grown with different nitrogen carrier flows, ranging from 150 to 300 sccm, and discussed the effect of carrier gas flows on their properties. We found a correlation between MoS₂ flake lateral size, shape, and number of layers, and we present a qualitative growth model based on changes in sulfur provision caused by different carrier flows. We show how the use of liquid precursors can allow for the synthesis of homogeneous, single-layer flakes up to 100 µm in lateral size by optimizing the gas flow rate. These results are essential for gaining a deeper understanding of the growth process of MoS₂.

Monolayer molybdenum disulfide is a semiconducting 2D material presenting very appealing characteristics for its incorporation into electronic flexible devices. At present, atomic vacancies in its structure are known to significantly affect its properties. Nonetheless, the effects of electron irradiation on it are still under investigation. In this work, the structural, electronic, and optical properties of monolayer molybdenum disulfide are studied before and after electron irradiation. By analyzing samples either obtained via a mechanical exfoliation process or grown via chemical vapor deposition, we show that following irradiation no significant change is present. This result indicates a strong resistance to the effect of electron irradiation at energies able to induce the formation of sulfur vacancies. By comparing our results to the current literature, we hypothesize that previously reported effects of electron irradiation are either due to the formation of molybdenum vacancies or to ionization of the electronic shell of this material. The presented results help to shed light on the role of atomic vacancies on the properties of this 2D material from a fundamental point of view and on its usage in extreme environment applications.

The integration of 2D molybdenum disulfide (MoS ₂ ) with gallium nitride (GaN) enables many interesting (opto)electronic applications, such as heterojunction diodes and UV/visible photodetectors, whose performances crucially depend on the thickness uniformity, strain and doping of MoS ₂ films and on the energy band alignment at the interface. This work reports a multiscale electro‐optical characterization of large size (∼100 µm) monolayer (1L) MoS ₂ flakes directly grown on n‐GaN and, for comparison, on a SiO ₂ /Si substrate by liquid‐precursors‐intermediated chemical vapor deposition. XPS and micro‐Raman mapping revealed a superior crystalline quality, lower average strain ε ≈ −0.06% and higher n‐type doping n ≈ 0.7 × 10 ¹³ cm ⁻² for 1L‐MoS ₂ grown on GaN, as compared to MoS ₂ grown under identical conditions on the amorphous SiO ₂ surface. Nanoscale current‐voltage mapping by C‐AFM showed a significantly reduced Schottky barrier (Φ _B = 0.57 ± 0.06 eV) at 1L‐MoS ₂ /GaN interface as compared to the bare GaN surface. This result, combined with a MoS ₂ /n‐GaN work function difference W _MoS2 ‐W _GaN ≈ 360 meV evaluated by KPFM mapping, revealed a type‐I band alignment at the heterojunction. Finally, photocurrent measurements on macroscopic Ni/n‐GaN, Ni/MoS ₂ /n‐GaN and Ni/MoS ₂ /SiO ₂ lateral devices under illumination with photon energies from ∼2 to ∼5 eV showed superior electro‐optical performances of Ni/MoS ₂ /n‐GaN heterojunctions both in the visible and UV range.