Two-Dimensional Indium Nitride Realized via Confinement Heteroepitaxy

Novel confinement techniques facilitate the formation of non-layered two-dimensional (2D) III-V semiconductors, e.g. GaN, with thickness-dependent optoelectronic properties. However, a gap lies in the experimental demonstration of 2D InN with its true atomic structure. Here, we demonstrate the formation of highly crystalline bilayer InN, at the bilayer quasi-free-standing epitaxial graphene (QFEG)/SiC (0001) interface via intercalation of metallic In and subsequent nitridation. Our scanning transmission electron microscopy (STEM) studies show that 2D InN is epitaxial to the underlying SiC (0001) with R3M space group, verified via Density Functional Theory. Furthermore, vertical transport studies on QFEG/2D InN/n-SiC demonstrate that the ohmic behavior of the QFEG/SiC transforms into tunneling junction via 2D InN intercalation. Importantly, electron energy loss spectroscopy (EELS) and transport analyses demonstrate that the band gap of 2D InN is ~2 eV, which is significantly larger than the one of bulk InN (0.7 eV). These results suggest strong quantum confinement effects for the InN in 2D limit.