Mid-infrared electroluminescence from coupled quantum dots and wells

Room temperature electroluminescence between 1.7-2.6 mum has been observed from coupled quantum dots and quantum wells in the InAs/InSb/GaSb materials system. The samples studied consist of a single narrow InAs quantum well grown below a layer of InSb quantum dots in a GaSb matrix. The thickness of the GaSb spacer layer lowers the energy from that of a quantum well alone but with a dependence that cannot be described solely through electronic coupling of the wave functions. A sharp transition occurs after a single monolayer coverage of GaSb either due to structural changes in the quantum dots or from shrinkage of the quantum well. For slightly thicker layers the emission energy can be explained by segregation during growth or strain-mediated correlation of the localized states in the system. (C) 2004 American Institute of Physics.