Abstract
Defects in Ge0.947Sn0.053 layers grown using molecular beam epitaxy on (001) Si substrates with 4.9% mismatch are investigated using optical, scanning, and transmission electron and atomic force microscopies. It is shown that the strain relaxation occurs via the introduction of 90° misfit dislocations of short length, at the Ge0.947Sn0.053/Si interface. An irregular morphology in the form of mounds is observed on the surface of epitaxial Ge1−xSnx (0.031 ≤ x ≤ 0.093) and is found to be associated with carbon impurities at the hetero-interface. A low-cost and fast defect selective wet etching technique is described to determine the etch pit density in epitaxial Ge1−xSnx with a low Sn content (≤5.3%). On the basis of etch pit morphology, different defects, e.g., dislocations, stacking faults, and crystal originated particles, are distinguished.
Published Version
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