Transport at the Epitaxial Interface between Germanium and Functional Oxides

Combining functional oxides with conventional semiconductors provides the potential for transformational advancement of microelectronic devices. Harnessing the full spectrum of oxide functionalities requires current transport between the oxide and the semiconductor. This aspect is addressed by controlling the electronic barrier at an interface between a ferroelectric oxide, BaTiO₃, and germanium. For the aligned conduction bands of germanium and BaTiO₃, as measured by spectroscopy, current transport is controlled by the barrier between the top metal electrode and the bands of the BaTiO₃. Capacitance-voltage analysis of metal-oxide-semiconductor devices further shows that the semiconductor's Fermi level can be moved by a field effect. These results demonstrate a viable approach for electronically bridging the functionalities of oxides directly with a common semiconductor.