Interfacial reactions of Mn/GaAs thin films

Mn thin films were deposited in situ on molecular beam epitaxy grown GaAs(001) surfaces at 0degreesC. Postgrowth anneals of the Mn/GaAs samples were done at 200, 300, and 400degreesC for times ranging from 0.5 to 30 h. Rutherford backscattering spectrometry, x-ray diffraction, and transmission electron microscopy show that for samples annealed at 300degreesC the interfacial reactions initially result in the formation of an epitaxial two phase region (Mn2As and MnGa) with an average composition of Mn0.6Ga0.2As0.2. The rate of reaction between the Mn and GaAs shows a square root of time dependence, indicating that the reactions are diffusion limited. (C) 2004 American Institute of Physics.