Optical and structural properties of p -doped Ge/SiGe multiple quantum wells for mid-infrared photonics

We present a detailed study of hole-doped Ge/SiGe multiple quantum wells as a promising material platformformid-infrared photonics. The heterostructures were grown on SiGe virtual substrates using low-energy plasmaenhancedchemical vapor deposition. Structural and compositional analyses via atom probe tomography andx-ray diffraction were employed to assess the crystal quality and retrieve the compositional profiles. The opticalresponse of the samples, in the 4–12-μm wavelength range, was investigated as a function of the temperature andcomplementary Hall-effect measurements were performed providing insights into the temperature evolution ofthe electrical transport properties. In addition, a well-established tight-binding model was used to reproduce andinterpret the experimental results starting from the calculated valence band structure.