Epitaxial growth of strained Ge films on GaAs(001)

Ge films were grown epitaxially as well as pseudomorphically on GaAs(001) s ubstrates at different temperatures using high-vacuum magnetron sputtering. The crystal quality of the resultant layers was examined by high-resolutio n X-ray diffraction (HRXRD). The rocking curves of Ge layer grown at temper atures greater than 470 degrees C show clear Pendellosung oscillations, con firming the high crystalline quality of the Ge layers. The angular position of the Ge diffraction peak is observed shifted from that for a pure Ge lay er grown pseudomorphically on GaAs. Calculations from the lattice parameter model are consistent with the supposition of Ge films with high concentrat ions of As or Ga, as reconfirmed by Hall effect measurements. Atomic Force Microscope (AFM) measurements performed to characterize the Ge surface, ind icate that the RMS surface roughness is typically 30 Angstrom, but that it can he as low as 3 Angstrom for intermediate temperatures, a value that com pares favorable with those obtained for molecular beam epitaxially grown ma terial. (C) 1999 Elsevier Science S.A. All rights reserved.