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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 2.9 eV 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.