MBE growth process of ferromagnetic MnAs on Si(111) substrates

We have studied initial growth process of metallic ferromagnetic MnAs thin films on Si(1 1 1) substrates by molecular beam epitaxy (MBE). MBE Growth study was performed under a variety of conditions (i.e. As-4/Mn flux ratio, substrate temperature T-sub) A nearly two-dimensional growth process took place at T-sub approximate to 350 degreesC, under a relatively small As-4/Mn flux ratio (approximate to 1.2), and eventually resulted in the formation of smooth surface. When the As-4/Mn flux ratio was increased at a fixed T-sub (approximate to 350 degreesC) or T-sub was increased at a fixed As-4/Mn flux ratio (approximate to 1.2), the growth mode of MnAs turned to three-dimensional resulting in the formation of islands. Structural characterizations and magnetization properties are presented and the results are discussed in relation to the growth process. (C) 2001 Elsevier Science B.V. All rights reserved.