Improved epitaxial growth of TbAs film on III–V semiconductors

In order to achieve high epitaxial quality of rocksalt TbAs, the authors studied the molecular beam epitaxy growth of TbAs films on zincblende (001) GaAs and (001) InP:Fe wafers. Despite the opposite strain condition of TbAs on these two substrates, mixed-orientation TbAs growth was observed on both substrates. However, the nucleation time and the continuing growth of the TbAs misoriented domains were influenced by the substrate type. By suppressing the growth of misoriented domains in the TbAs film, enhanced single-crystal orientation of TbAs grown on the (001) InP:Fe substrate was observed as compared to the (001) GaAs substrate. In addition, the cube-on-cube epitaxial arrangement of (001) TbAs with a thick film of up to ∼1150 nm is maintained on the (001) InP:Fe substrate but not on the (001) GaAs substrate. The improved TbAs film growth on the InP:Fe substrate exhibited enhanced optical properties when compared to that grown on the GaAs substrate, including a threefold reduction in the scattering rate. This largely improved optical property highlights the importance of increasing the epitaxial quality of TbAs films for future optoelectronic as well as other applications.