Epitaxial growth of Fe on GaAs by ion beam sputtering

The epitaxial growth of ferromagnetic metals onto semiconductors is being e xtensively studied, and one of the reasons is the potential application for magneto-electronic devices. For this, a good quality interface between mag netic metal and semiconductor is necessary. The work presented here is conc erned with Fe contacts grown epitaxially on (100) GaAs substrates. For this purpose, 25 nm thick Fe films were deposited under vacuum (similar to 10(- 7) Torr) by ion beam sputtering onto monocrystalline substrates. The deposi tion method consists in sputtering an iron target with argon ions. The ejec ted Fe atoms, having energy of about 10 eV, are then deposited onto the sub strate. The first part of the study deals with the optimisation of depositi on parameters such as substrate temperature and surface cleaning before spu ttering. In the second part, the deposited films are studied using X-ray di ffraction and high resolution transmission electron microscopy. The Fe film s deposited at room temperature are found to be polycrystalline. On the con trary, the Fe films deposited at about 300 degreesC are found to have a mon ocrystalline structure and to present a perfect epitaxial relationship with the (100) GaAs substrate. (C) 2001 Elsevier Science B.V. All rights reserv ed.