Hexagonal boron nitride (h-BN), together with other members of the van der Waals crystal family, has been studied for over a decade, both in terms of fundamental and applied research. Up to now, the spectrum of h-BN-based devices has broadened significantly, and systems containing the h-BN/III-V junctions have gained substantial interest as building blocks in, inter alia, light emitters, photodetectors, or transistor structures. Therefore, the understanding of electronic phenomena at the h-BN/III-V interfaces becomes a question of high importance regarding device engineering. In this study, we present the investigation of electronic phenomena at the h-BN/GaN interface by means of contactless electroreflectance (CER) spectroscopy. This nondestructive method enables precise determination of the Fermi level position at the h-BN/GaN interface and the investigation of carrier transport across the interface. CER results showed that h-BN induces an enlargement of the surface barrier height at the GaN surface. Such an effect translates to Fermi level pinning deeper inside the GaN band gap. As an explanation, we propose a mechanism based on electron transfer from GaN surface states to the native acceptor states in h-BN. We reinforced our findings by thorough structural characterization and demonstration of the h-BN/GaN Schottky diode. The surface barriers obtained from CER (0.60 ± 0.09 eV for GaN and 0.91 ± 0.12 eV for h-BN/GaN) and electrical measurements are consistent within the experimental accuracy, proving that CER is an excellent tool for interfacial studies of 2D/III–V hybrids.

Abstract2D intrinsic ferromagnetic materials are highly anticipated in spintronic devices due to their coveted 2D limited magnetism. However, 2D non‐layered intrinsic ferromagnets have received sporadic attention, which is largely attributed to the fact that their synthesis is still a great challenge. Significantly, manganese phosphide (MnP) is a promising non‐layered intrinsic ferromagnet with excellent properties. Herein, high‐quality 2D MnP single crystals formed over liquid metal tin (Sn) is demonstrated through a facile chemical vapor deposition technique. The introduction of liquid metal Sn provides a fertile ground for the growth of 2D MnP single crystals. Interestingly, 2D MnP single crystals maintain their intrinsic ferromagnetism and exhibit a Curie temperature above room temperature. The research enriches the diversity of 2D intrinsic ferromagnetic materials, opening up opportunities for further exploration of their unique properties and rich applications.

The current family of experimentally realized two-dimensional magnetic materials, based on 3d transition metal ions, possesses weak spin–orbit coupling. In contrast, we report a novel platform in a chemically bonded and layered oxide SrRu2O6. In bulk, this system is known for strong electron correlations and competing spin–orbit coupling. We present the synthesis and characterization of ultrathin nanosheets of SrRu2O6 along with first-principles calculations to explore their magnetic state. SrRu2O6 nanosheets are synthesized using a scalable technique of liquid exfoliation. Atomic force microscopy reveals that the thickness of the nanosheets varies between three and five monolayers. Experimental data also suggest that exfoliation occurs from the planes perpendicular to the c-axis wherein the intervening hexagonal Sr lattice separates the two-dimensional Ru honeycomb. The high-resolution transmission electron microscopy images indicate that the average interatomic spacing between the Ru layers is slightly reduced, which agrees with the density functional theory (DFT) calculations. The signatures of rotational stacking of the nanosheets are also observed. Within the first-principles calculations, we show that antiferromagnetism survives in these nanosheets. The experimental realization of graphene-like two-dimensional (2D) sheets of SrRu2O6 offers enormous possibilities to explore emergent properties associated with a magnetic honeycomb with large spin–orbit coupling, and this system is likely to have applications in the area of antiferromagnetic spintronics.

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