Growth of bulk like epitaxial films of Weyl semimetal TaAs on GaAs (001)

Three dimensional topological semimetals (TSMs) exhibit extraordinary properties such as extremely high mobility, conductivity and magnetoresistance stemming from their protected bandstructures. They are now emerging as excellent candidates for a wide variety of applications including spintronics, thermoelectrics, and catalysts. While there has been a great deal of success studying novel bulk single crystal TSMs, they are not suitable for device applications. Thus, there is a need to develop thin film TSMs compatible with semiconductor manufacturing to accelerate the adoption of TSMs into devices. We report epitaxial growth of thick bulk-like films of Weyl semimetal TaAs on GaAs(001) substrates using molecular beam epitaxy. TaAs has been widely studied in bulk crystal form but only synthesized in thin films as ultrathin materials (10-20 nm), in which electron transport is dominated by surface states. In this presentation we discuss growth strategies to realize thick (100-300 nm) single crystal films and eliminate secondary phases. We study the electronic structure using a combination of magnetotransport and angle resolved photoemission spectroscopy. We will also discuss the impact of epitaxial growth on intrinsic doping and magnetoresistance.