Characterization of Ge/Si0.16Ge0.84 multiple quantum wells on Ge-on-Si virtual substrate using piezoreflectance spectroscopy

A Ge/Si0.16Ge0.84 multiple quantum well (MQW) structure grown on a Ge-on-Si virtual substrate (Ge-VS) was characterized by using temperature dependent piezoreflectance (PzR) technique. Signals from every relevant portion of the sample, including Ge-VS, MQW and barriers were observed. The band gap blue-shifted and valence band splitting in the vicinity of the direct band-edge transitions of Ge revealed that the Ge-VS is compressively strained. A comprehensive analysis of the PzR spectra led to the identification of various quantum-confined interband transitions. In addition, the parameters that describe the temperature dependence of the excitonic transition energies were evaluated and found to be similar to that of the bulk Ge.