O2-Enhanced surface treatment of Ge epitaxially grown on Si for heterogeneous Ge technology

In this work, in order to investigate the effects of annealing gases on the quality of Ge epitaxially grown on Si substrate, ex-situ rapid thermal annealing (RTA) processes with different gases have been performed. The Ge-on-Si samples were prepared by different growth techniques using reduced-pressure chemical vapor deposition (RPCVD), and then, samples annealed in the N₂, forming gas (FG), and O₂ were compared with an unannealed one to confirm the improvements in Ge quality. To evaluate the material quality, photoluminescence (PL) measurements have been carried out for the samples at room temperature. Among the prepared samples, the O₂-annealed sample showed the highest PL signals regardless of growth techniques, which supports that an ex-situ RTA in the O₂ ambient would be an effective technique for surface treatment of Ge in the fabrication processes of Ge-based electronic and photonic devices.