Room-temperature electroluminescence from single-period (CdF2/CaF2) inter-subband quantum cascade structure on si substrate

Near-infrared electroluminescence from a single-period (CdF2/CaF2) inter-subband quantum cascade structure on a Si substrate is reported. The CdF2/CaF2 heterostructure is a good candidate for realizing a Si-based short-wavelength quantum cascade laser because of its large conduction band discontinuity of 2.9eV and small lattice mismatch with the Si substrate. In the experiment, an active region consisting of (CdF2/CaF2) heterostructures was grown epitaxially on the Si substrate by molecular beam epitaxy, and an Au/Al electrode was evaporated on the active region. The wafer was polished mechanically and cleaved. Electroluminescence from the device was observed in the near-infrared region at room temperature for the first time.