GaFeAs: a diluted magnetic semiconductor grown by molecular beam epitaxy

We prepared a novel diluted magnetic semiconductor of GaFeAs grown on (001) GaAs substrates using molecular beam epitaxy (MBE). The low growth tempera ture of the buffered GaAs layers is a key factor necessary for the creation of GaFeAs epilayers, without the anomalous nucleation of Fe atoms. The max imum Fe concentration of 1.5 x 10(21) cm(-3), which is the highest reported value, was successfully doped uniformly in GaAs. The 1 x 1-reflection high -energy electron diffraction patterns, indicating a well-ordered flat surfa ce, were maintained during the growth of GaFeAs. X-Ray diffraction measurem ents showed that the peak shifted toward the higher angle side with an incr easing Fe content in GaAs, implying that Fe atoms substitutionally occupy t he GaAs lattice sites. Magnetization measurements revealed that the GaFeAs epilayers were predominantly paramagnetic, and that 5% of the total Fe atom s were segregated in the MBE-grown GaFeAs epilayers. (C) 2000 Published by Elsevier Science S.A. All rights reserved.