Comparative Studies of the Growth and Characterization of Germanium Epitaxial Film on Silicon (001) with 0A° and 6A° Offcut

The quality of germanium (Ge) epitaxial films grown directly on silicon (Si) (001) with 0A degrees and 6A degrees offcut orientation using a reduced-pressure chemical vapor deposition system is studied and compared. Ge film grown on Si (001) with 6A degrees offcut presents similar to 65% higher threading dislocation density and higher root-mean-square (RMS) surface roughness (1.92 nm versus 0.98 nm) than Ge film grown on Si (001) with 0A degrees offcut. Plan-view transmission electron microscopy also reveals that threading dislocations are more severe (in terms of contrast and density) for the 6A degrees offcut. In addition, both high-resolution x-ray diffraction and Raman spectroscopy analyses show that the Ge epilayer on 6A degrees offcut wafer presents higher tensile strain. The poorer quality of the Ge film on Si (001) with 6A degrees offcut is a result of an imbalance in Burgers vectors that favors dislocation nucleation over annihilation.