Introduction of Sr into Bi2Se3 thin films by molecular beam epitaxy

SrxBi2Se3 is a candidate topological superconductor, but its superconductivity requires the intercalation of Sr into the van der Waals gaps of Bi2Se3. We report the synthesis of SrxBi2Se3 thin films by molecular beam epitaxy, and we characterize their structural, vibrational, and electrical properties. X-ray diffraction and Raman spectroscopy show evidence of substitutional Sr alloying into the structure, while transport measurements allow us to correlate the increasing Sr content with an increased n-type doping, but do not reveal superconductivity down to 1.5 K. Our results suggest that Sr predominantly occupies sites within a quintuple layer, simultaneously substituting for Bi and as an interstitial. We, thus, motivate future density functional theory studies to further investigate the energetics of Sr substitution into Bi2Se3.