The authors propose a Ge/Ge0.76Si0.19Sn0.05 quantum cascade laser using intersubband transitions at L valleys of the conduction band which has a “clean” offset of150 meV situated below other energy valleys (Γ,X). The entire structure is strain-free because the lattice-matched Ge and Ge0.76Si0.19Sn0.05 layers are to be grown on a relaxed Ge buffer layer on a Si substrate. Longer lifetimes due to the weaker scattering of nonpolar optical phonons reduce the threshold current and potentially lead to room temperature operation.
Sun, Greg; Cheng, H. H.; Menéndez, J.; Khurgin, Jacob B.; and Soref, R. A., "Strain-free Ge/GeSiSn quantum cascade lasers based on L-valley intersubband transitions" (2007). Physics Faculty Publications. 20.
American Institute of Physics
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