In-situ control during molecular beam epitaxy:: impurity incorporation and dissimilar materials epitaxial growth

Reflection high-energy electron diffraction and reflectance difference spectroscopy are used to monitor in real-time the Si incorporation as well as nucleation and growth of MnAs on different well-defined GaAs(001) templates. It is demonstrated that Si incorporation into the trenches of the (2 x 4)beta 2 structure occurs randomly whereas for Si deposition on a (2 x 4)alpha template a high degree of ordering is observed. This is confirmed by real-space imaging using scanning tunneling microscopy. Despite the dissimilar NiAs structure ferromagnetic MnAs can be grown in high structural quality on GaAs(001)-d(4 x 4), as evidenced by real-time measurements as well as high-resolution transmission electron microscopy. The exposed ((1) over bar 1.0)MnAs surface develops stoichiometry dependent reconstructions. These findings are promising in view of the integration of ferromagnetic material within the framework of the well developed GaAs technology. (C) 2000 Elsevier Science S.A. All rights reserved.