Ultrathin GaN Crystal Realized Through Nitrogen Substitution of Layered GaS

Advancing Nanoelectronics Applications: Progress in Non-van der Waals 2D Materials

“…62,63 In this process, the metal skeleton remains, and chalcogen atoms are liberated from the lattice under high temperature (600− 800 °C), followed by the formation of metal−nitrogen bonds in the NH 3 atmosphere. 62,63,91 Li et al further showed that the conversion initiates from both the edge and the defect sites on the surface of a precursor flake, followed by an epitaxial conversion process. 136,137 The converted nitride crystals are observed to share the same crystal orientation as the MoS 2 precursor flakes.…”

“…Cao et al also reported the blue shift of photoluminescence emission in 2D GaN with sample thicknesses, where the emission peak shifts from 3.5 eV (25 nm thick) to 3.7 eV (4.4 nm thick). 63 In addition to the modulation of bandgap energies, recent investigations have unveiled a noteworthy reversal in the magnetic ordering of α-Fe 2 O 3 as it undergoes dimensional reduction from bulk (hematite) to a 2D form known as hematene. 89,114 Extensive studies have traditionally classified hematite as a weak ferromagnetic (FM) material above the Morin transition temperature (T M ) of approximately 265 K, transitioning into an antiferromagnetic (AFM) state below T M .…”

“…They also notice that the conversion works the best for MoS 2 flakes with the thickness in the range of 5 to 15 nm (2 to 6 nm in term of Mo 5 N 6 ). They further demonstrated that this approach could be applied to make other non-vdW metal nitrides, such as W 5 N 6 , TiN and GaN by converting the vdW WS 2 , TiS 2 and GaS, respectively. , In this process, the metal skeleton remains, and chalcogen atoms are liberated from the lattice under high temperature (600–800 °C), followed by the formation of metal–nitrogen bonds in the NH 3 atmosphere. ,, Li et al further showed that the conversion initiates from both the edge and the defect sites on the surface of a precursor flake, followed by an epitaxial conversion process. , The converted nitride crystals are observed to share the same crystal orientation as the MoS 2 precursor flakes.…”

“…They further demonstrated that this approach could be applied to make other non-vdW metal nitrides, such as W 5 N 6 , TiN and GaN by converting the vdW WS 2 , TiS 2 and GaS, respectively. 62,63 In this process, the metal skeleton remains, and chalcogen atoms are liberated from the lattice under high temperature (600− 800 °C), followed by the formation of metal−nitrogen bonds in the NH 3 atmosphere. 62,63,91 Li et al further showed that the conversion initiates from both the edge and the defect sites on the surface of a precursor flake, followed by an epitaxial conversion process.…”

“…Moreover, non-vdW materials are more abundant in nature, offering more possibilities and expanding the design space of 2D materials. In Figure b, we summarize the elements present in the experimentally achieved vdW and non-vdW materials, in both 2D and bulk form, in a periodic table. ,,,,− A list of 2D material examples for each element is given in Table . Calculations predicted that only less than 2.5% of all experimentally known crystals (2,662 out of 108,423) possess weak vdW interactions, which could potentially allow downscaling of the crystal into their low-dimensional form using conventional exfoliation method .…”