Hole-doped Ge-rich SiGe parabolic quantum wells for mid-infrared photonics

The design, growth and characterization of hole-doped Ge-rich SiGe parabolic quantum wells are discussed. The heterostructures were epitaxially grown by low-energy plasma-enhanced chemical vapor deposition and characterized by secondary ion mass spectroscopy, scanning transmission electron microscopy and X-ray diffraction measurements. Fourier-transform infrared spectroscopy revealed an almost temperature- and doping-independent intersubband transition at around 120 meV which is stable up to room temperature, making these heterostructures promising candidates for the realization of optoelectronic devices working in the fingerprint region.