Room temperature and narrow intersubband electroluminescence from ZnCdSe/ZnCdMgSe quantum cascade laser structures

We report ZnCdSe/ZnCdMgSe Quantum Cascade structures with “two-phonon” and “bound-to-continuum” active region designs. The electroluminescence shows more than 3 times higher luminescence efficiency and 40% narrower linewidth (<30 meV) than previous reports. The measured turn-on voltage matches closely the calculated value, indicating the improved electron transport characteristics in these structures. A waveguide design suitable for mode confinement in this material system is also presented, which resulted in a structure with a single narrow electroluminescence peak for all temperatures from 80 to 300 K.