Epitaxial Growth of Strained Ge Films on GaAs(001)

Abstract

Ge films were grown epitaxially as well as pseudomorphically on GaAs(001) substrates at different temperatures using high-vacuum magnetron sputtering. The crystal quality of the resultant layers was examined by high-resolution X-ray diffraction (HRXRD). The rocking curves of Ge layer grown at temperatures greater than 470°C show clear Pendellösung oscillations, confirming 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 layer grown pseudomorphically on GaAs. Calculations from the lattice parameter model are consistent with the supposition of Ge films with high concentrations of As or Ga, as reconfirmed by Hall effect measurements. Atomic Force Microscope (AFM) measurements performed to characterize the Ge surface, indicate that the RMS surface roughness is typically 30 Å, but that it can be as low as 3 Å for intermediate temperatures, a value that compares favorable with those obtained for molecular beam epitaxially grown material.