Asymmetric Hybrid A1(Ga)SbAs/InAs/Cd(Mg)Se Heterostructures for Mid-IR LEDS and Lasers
RUSSIAN ACADEMY OF SCIENCES SAINT PETERSBURG IOFFE PHYSICAL-TECHNICAL INST
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A hybrid double heterostructure with large asymmetric band offsets, combining AlAsSbInAs as a III-V part and CdMgSeCdSe as a II-VI part, has been proposed as a basic element of a mid-infrared laser structure design. The p-i-n diode structure has been successfully grown by molecular beam epitaxy MBE and exhibited an intense long-wavelength electroluminescence at 3.12 micrometers 300 K. A II-VI MBE growth initiation with a thin ZnTe buffer layer prior to the CdMgSe deposition results in a dramatic reduction of defect density originating at the II-VIIII-V interface, as demonstrated by transmission electron microscopy. A less than 10 times reduction of electroluminescence intensity from 77 to 300 K indicates an efficient carrier confinement in the InAs active layer due to high potential barriers in conduction and valence bands, estimated as delta Esub c 1.28 eV and delta Esub v 1.6 eV. An increase in the pumping current results in a super-linear raising the EL intensity. The type of band line up at the coherent InAsCd1-xMgxSe interface is discussed for 0 - - 0.2, using experimental data and theoretical estimations within a model-solid theory.
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