THz emission from n-type Ge/SiGe quantum cascade structures

We report electroluminescence at 14meV and 20meV from a n-type Ge/Si0.15Ge0.85 quantum cascade heterostructure on Si substrate grown by ultra-high vacuum chemical vapour deposition. The electroluminescence signal of the single quantum well active region design, extracted through diffraction gratings from mesa structures, is compared with its GaAs counterpart.The spectral features agree well with modeling based on Non-equilibrium Green's function calculations. The observed electroluminescence peaks show a full width at half maximum of 3meV and 4meV. These results are an important step towards the realization of an n-type THz quantum cascade laser on a non-polar material system.