Epitaxial growth of Fe on GaAs by ion beam sputtering

The epitaxial growth of ferromagnetic metals onto semiconductors is being extensively studied, and one of the reasons is the potential application for magneto-electronic devices. For this, a good quality interface between magnetic metal and semiconductor is necessary. The work presented here is concerned with Fe contacts grown epitaxially on (1 0 0) GaAs substrates. For this purpose, 25 nm thick Fe films were deposited under vacuum (∼10−7 Torr) by ion beam sputtering onto monocrystalline substrates. The deposition method consists in sputtering an iron target with argon ions. The ejected Fe atoms, having energy of about 10 eV, are then deposited onto the substrate. The first part of the study deals with the optimisation of deposition parameters such as substrate temperature and surface cleaning before sputtering. In the second part, the deposited films are studied using X-ray diffraction and high resolution transmission electron microscopy. The Fe films deposited at room temperature are found to be polycrystalline. On the contrary, the Fe films deposited at about 300°C are found to have a monocrystalline structure and to present a perfect epitaxial relationship with the (1 0 0) GaAs substrate.