Growth and characterization of germanium epitaxial film on silicon (001) using reduced pressure chemical vapor deposition

High quality germanium (Ge) epitaxial film is grown directly on silicon (001) substrate using a “three-step growth” approach in a reduced pressure chemical vapor deposition system. The growth steps consist of sequential low temperature (LT) at 400 °C, intermediate temperature ramp (LT-HT) of ~ 6.5 °C/min and high temperature (HT) at 600 °C. This is followed by post-growth anneal in hydrogen at temperature ranging from 680 to 825 °C. Analytical characterizations have shown that the Ge epitaxial film of thickness ~ 1 μm experiences thermally induced tensile strain of 0.20% with a threading dislocation density of < 10⁷ cm^− 2 under optical microscope and root mean square roughness of ~ 0.9 nm. Further analysis has shown that the annealing time at high temperature has an impact on the surface morphology of the Ge epitaxial film. Further reduction in the RMS roughness can be achieved either through chemical mechanical polishing or to insert an annealing step between the LT-HT ramp and HT steps.