Epitaxial BaSnO3 and SrSnO3 perovskite growth on SrTiO3(001) via atomic layer deposition

Abstract

The authors report epitaxial BaSnO3(001) and SrSnO3(001) growth on SrTiO3(001) (STO) substrates via atomic layer deposition (ALD) at 180 °C, where the BaSnO3 growth rate is 0.46 ± 0.03 Å and the SrSnO3 growth rate is 0.69 ± 0.04 Å per ALD unit cycle. Reflection high-energy electron diffraction, x-ray diffraction (XRD), and rocking curve analyses verify the single crystalline nature of BaSnO3(001) and SrSnO3(001) thin films on STO(001), while the atomic force microscopy analyses reveal the smooth surface of the stannate films with rms roughness values of ∼0.4 nm, which is only slightly higher than the STO substrate roughness of 0.32 nm. Out-of-plane XRD and reciprocal space mapping show that both BaSnO3(001) and SrSnO3(001) (∼10 nm) are fully relaxed on STO(001), owing to the large lattice mismatches (5.1% for BaSnO3/STO and 3.2% for SrSnO3/STO). The visible light transmittance spectra indicate that ALD-grown BaSnO3 and SrSnO3 thin films have high transparency at 400–800 nm that matches the transparency of STO(001) substrates.