Squeezed metallic droplet with tunable Kubo gap and charge injection in transition metal dichalcogenides

Shrinking the size of a bulk metal into nanoscale leads to the discreteness of electronic energy levels, the so-called Kubo gap. Renormalization of the electronic properties with a tunable and size-dependent Kubo gap renders fascinating photon emission and electron tunneling. In contrast with usual three-dimensional (3D) metal clusters, here we demonstrate that Kubo gap can be achieved with a two-dimensional (2D) metallic transition metal dichalcogenide (i.e., 1T'-phase MoTe2) nanocluster embedded in a semiconducting polymorph (i.e., 1H-phase MoTe2). Such a 1T'-1H MoTe2 nanodomain resembles a 3D metallic droplet squeezed in a 2D space which shows a strong polarization catastrophe while simultaneously maintains its bond integrity which is absent in traditional delta-gapped 3D clusters. The weak screening of the host 2D MoTe2 leads to photon emission of such pseudo-metallic systems and a ballistic injection of carriers in the 1T'-1H-1T' homojunctions which may find applications in sensors and 2D reconfigurable devices.