Thin film growth of Ba(Zn,Fe)2As2 by molecular beam epitaxy

Abstract

• We established a one-step growth process of BaZn 2 As 2 films by molecular beam epitaxy. • We also grew Ba(Zn 1- x Fe x ) 2 As 2 thin films, which was not reported so far. • We found that a substitution of Fe for Zn stabilized the target phase. • We confirmed that Ba(Zn 1- x Fe x ) 2 As 2 films up to x = 0.16 are n -type semiconductors. We have grown Ba(Zn 1- x Fe x ) 2 As 2 thin films by molecular beam epitaxy. Epitaxial thin films with various Fe contents up to x = 0.16 were obtained by employing fluoride substrates and supplying Zn and As in excess. The film of the parent compound BaZn 2 As 2 showed a metallic behavior in the temperature range of 50–300 K, although semiconducting behavior with a bandgap of 0.23 eV has been reported for a polycrystalline bulk sample. The metallic behavior can be ascribed to a defect layer near the film/substrate interface that was found by a cross-sectional microstructure observation. For the Fe-substituted films, on the other hand, no such defect layer was observed, and the temperature dependence of resistivity showed semiconducting behavior. BaZn 2 As 2 is known as a parent compound of diluted magnetic semiconductors, but the magnetization measurements of the Fe doped films showed no evidence of ferromagnetic order.