Room temperature InAs/InAs1−xSbx single quantum well light emitting diodes with barriers for improved carrier confinement

Abstract

Room temperature InAs/InAs1−xSbx single quantum well light emitting diodes for the mid-infrared region that emit at λ∼4.2 μm with an internal efficiency of 2.6% and pulsed output powers of more than 110μW/A are studied. The structures are grown by molecular beam epitaxy and include an InAl0.17As0.83 barrier for enhanced electron confinement in the active region. Comparison with an identical structure grown without the barrier demonstrates an improvement in room temperature efficiency by a factor of more than six. Additional magneto-electroluminescence measurements reveal several very narrow subband transitions with a typical FWHM of only 10 meV. The broad (∼40 meV) LED emission spectra are therefore due to multiple bound states in the quantum wells. This shows the high material quality of the quantum wells, and that the quasi-Fermi energy separation, even at low (150 A/cm2) current densities, exceeds ∼30 meV and promises excellent prospects for high gain in laser diode structures made from these heterostructures.