Rapid Lab‐Based In Situ Monitoring of Germanium Multiple Quantum Wells Interdiffusion
Diana Ryzhak, Elena Campagna, Markus Andreas Schubert, Yuji Yamamoto, Oliver Skibitzki, Enrico Talamas Simola, Monica De Seta, Giovanni Capellini, Marvin Hartwig ZoellnerABSTRACT
The Silicon–Germanium (Si‐Ge) interdiffusion and its impact on the structural and optical properties of Ge/Si 0 .₁₈Ge 0 .₈ 2 multiple quantum wells (MQW) grown on Si by industry‐standard chemical vapor deposition are investigated. The structures, consisting of 186 periods, each 27 nm thick, are studied by in situ high‐resolution X‐ray diffraction during short‐time annealing (≤30 min) between 700°C and 760°C. The evolution of superlattice peak intensities reveals Arrhenius‐type diffusion with an activation energy of ∼3.4 eV. The extracted interdiffusivities agree well with the Dong model, including strain‐dependent corrections. Micro‐photoluminescence measurements show both direct (Γ‐HH) and indirect (L‐HH) optical transitions. The annealing process induces bandgap widening, and results in a progressive degradation of quantum confinement. A blueshift of the Γ transition (∼0.25 eV) is observed prior to complete intermixing. These results highlight the strong influence of interdiffusion on structural and optical properties, emphasizing the need for precise thermal control in CMOS‐compatible optoelectronic devices.