An Ultrathin Single Crystalline Relaxor Ferroelectric Integrated on a High Mobility Semiconductor.

Moghadam, Reza M; Xiao, Zhiyong; Ahmadi-Majlan, Kamyar; Grimley, Everett D; Bowden, Mark; Ong, Phuong-Vu; Chambers, Scott A; Lebeau, James M et al. · Nano Lett · 2017

basic_science · Level V

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Abstract

The epitaxial growth of multifunctional oxides on semiconductors has opened a pathway to introduce new functionalities to semiconductor device technologies. In particular, the integration of gate materials that enable nonvolatile or hysteretic functionality in field-effect transistors could lead to device technologies that consume less power or allow for novel modalities in computing. Here we present electrical characterization of ultrathin single crystalline SrZr<sub>x</sub>Ti<sub>1-x</sub>O<sub>3</sub> (x = 0.7) films epitaxially grown on a high mobility semiconductor, Ge. Epitaxial films of SrZr<sub>x</sub>Ti<sub>1-x</sub>O<sub>3</sub> exhibit relaxor behavior, characterized by a hysteretic polarization that can modulate the surface potential of Ge. We find that gate layers as thin as 5 nm corresponding to an equivalent-oxide thickness of just 1.0 nm exhibit a ∼2 V hysteretic window in the capacitance-voltage characteristics. The development of hysteretic metal-oxide-semiconductor capacitors with nanoscale gate thicknesses opens new vistas for nanoelectronic devices.