Heteroepitaxial oxide structures grown by pulsed organometallic beam epitaxy (POMBE)

We describe the design, construction, and use of pulsed organometallic beam epitaxy (POMBE), a plasma-enhanced CVD technique to grow oxide heterostructures. Solid-state precursors are sampled in the gas line via quartz crystal monitors and injected into the O2microwave plasma with pulse time durations of a few seconds. The precursors are injected through pneumatic valves in a heated valve box. The valves and microwave power are under computer control. The microwave plasma is ramped between a forward power of 600 and 1500W to improve film epitaxy. We use POMBE to grow epitaxial BaYZrO3/MgO, Y-ZrO2/LAO, and YBa2Cu3O7/Y-ZrO2/LAO structures. The processing parameters leading to the heteroepitaxy are described. The best epitaxy results in X-ray FWHM of 0.12°, 0.38°, and 0.87° for BaYZrO3, Y-ZrO2, and YBa2Cu3O7, respectively. We show the advantages of the POMBE technique over that of plasma-enhanced CVD. Selected TEM results of the heteroepitaxial oxide structures are shown, and the role that temperature plays in the oxide epitaxy. The epitaxy of BaYZrO3is the first described in the literature, and that of YSZ is among the best reported.