Epitaxial La-doped SrTiO3 on silicon: A conductive template for epitaxial ferroelectrics on silicon

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Abstract
Use of an epitaxial conducting template has enabled the integration of epitaxial ferroelectric perovskites on silicon. The conducting template layer, LaxSr1−xTiO3 (LSTO), deposited onto (001) silicon wafers by molecular-beam epitaxy is then used to seed {001}-oriented epitaxial perovskite layers. We illustrate the viability of this approach using PbZr0.4Ti0.6O3 (PZT) as the ferroelectric layer contacted with conducting perovskite La0.5Sr0.5CoO3 (LSCO) electrodes. An important innovation that further facilitates this approach is the use of a low-temperature (450 °C) sol–gel process to crystallize the entire ferroelectric stack. Both transmission electron microscopy and x-ray diffraction analysis indicate the LSCO/PZT/LSCO/LSTO/Si heterostructures are epitaxial. The electrical response of ferroelectric capacitors (for pulse widths down to 1 μs) measured via the underlying silicon substrate is identical to measurements made using conventional capacitive coupling method, indicating the viability of this approach.