Enhanced performance in transparent conducting materials at the interface of a wide band gap semiconductor and a correlated metal

Abstract

Several classes of inorganic transparent conducting coatings are available (broad band wide band gap semiconductors, noble metals, amorphous oxides and correlated metals), with peak performance depending on the layer thickness. Correlated metallic transition metal oxides have emerged as potential competitive materials for small coating thicknesses, but their peak performance remains one order of magnitude below other best in class materials. By exploiting the charge transfer at the interface between a correlated metal (SrNbO₃) and a wide band gap semiconductor (SrTiO₃), we show that pulsed laser deposition-grown SrNbO₃ heterostructures on SrTiO₃ outperform correlated metals by an order of magnitude. The apparent increase in carrier concentration confirms that an electronically active interfacial layer is contributing to the transport properties of the heterostructure. The correlated metallic electrode allows the extraction of high mobility carriers resulting in enhanced conductivity for heterostructures with thicknesses up to 20 nm. The high optical absorption of the high mobility metallic interface does not have a detrimental effect on the transmission of the heterostructure due to its small thickness. The charge transfer-driven enhanced electrical properties in correlated metal – wide band gap semiconductor heterostructures offer a distinct route to high performance transparent conducting materials.