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 degrees C, intermediate temperature ramp (LT-HT) of similar to 6.5 degrees C/min and high temperature (HT) at 600 degrees C. This is followed by post-growth anneal in hydrogen at temperature ranging from 680 to 825 degrees C. Analytical characterizations have shown that the Ge epitaxial film of thickness similar to 1 mu m experiences thermally induced tensile strain of 0.20% with a threading dislocation density of <10(7) cm(-2) under optical microscope and root mean square roughness of similar to 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. (C) 2011 Elsevier B.V. All rights reserved.