High-temperature oxygen-assisted molecular beam epitaxy of BaWO$_4$ on W(110): growth mechanism and structural characterization

We have studied the growth of barium tungstate, BaWO$_4$, by high-temperature oxygen-assisted molecular beam epitaxy on W(110). Barium tungstate grows in the form of isosceles triangular-shaped islands, tens of micrometers wide and tens of nanometers in height. The growth was monitored in real time by low-energy electron microscopy and characterized in situ by low-energy electron diffraction, X-ray absorption and X-ray photoelectron spectroscopies. Further ex situ characterization was performed by optical and atomic force microscopies and Raman spectroscopy. Barium tungstate growth on W(110) was performed by dosing only barium in a molecular oxygen atmosphere due to incorporation of W atoms from the W(110) substrate. The islands correspond to the BaWO$_4$ (011) crystallographic orientation and their sides are aligned along the [001] and [1$\bar{1}$1] directions of the BaWO$_4$ crystal.