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A method to remove the misfit dislocations and reduce the threading dislocations density (TDD) in the germanium (Ge) epilayer growth on a silicon (Si) substrate is presented. The Ge epitaxial film is grown directly on the Si (001) donor wafer using a “three-step growth” approach in a reduced pressure chemical vapour deposition. The Ge epilayer is then bonded and transferred to another Si (001) handle wafer to form a germanium-on-insulator (GOI) substrate. The misfit dislocations, which are initially hidden along the Ge/Si interface, are now accessible from the top surface. These misfit dislocations are then removed by annealing the GOI substrate. After the annealing, the TDD of the Ge epilayer can be reduced by at least two orders of magnitude to <5 × 106 cm−2.

Fabrication and characterization of germanium-on-insulator through epitaxy, bonding, and layer transfer

The quality of germanium (Ge) epitaxial film grown directly on a silicon (Si) (001) substrate with 6° off-cut using conventional germane precursor in a metal organic chemical vapour deposition (MOCVD) system is studied. The growth sequence consists of several steps at low temperature (LT) at 400 °C, intermediate temperature ramp (LT-HT) of ∼10 °C/min and high temperature (HT) at 600 °C. This is followed by post-growth annealing in hydrogen at temperature ranging from 650 to 825 °C. The Ge epitaxial film of thickness ∼ 1 μm experiences thermally induced tensile strain of 0.11 % with a treading dislocation density (TDD) of ∼107/cm2 and the root-mean-square (RMS) roughness of ∼ 0.75 nm. The benefit of growing Ge epitaxial film using MOCVD is that the subsequent III-V materials can be grown in-situ without the need of breaking the vacuum hence it is manufacturing worthy