Mid-IR interband cascade light emitting diodes based on type-II quantum wells

We can circumvent the fast phonon scattering loss in type-I QC lasers, while retaining the cascaded tunneling injection advantage, by utilizing photon emission between an electron state and a hole state in a new class of QC lasers based on type-II QWs, which was first proposed by Yang and is referred to as type-II QC lasers. The type-II QC lasers can have a higher radiative efficiency because the phonon relaxation process is greatly suppressed in an interband transition. Here, we report the first observation of mid-IR electroluminescence in such a type-II QC laser structure. We illustrates the band diagram of two periods of an InAs-AlSb-GaSb type-II QC laser diode under a forward bias.