Multiple wavelength anisotropically polarized mid-infrared emission from InAs quantum dots

Multiple wavelength, anisotropically polarized midinfrared electroluminescence from self-assembled InAs quantum dots grown in AlGaAs∕GaAs heterostructures has been observed at 77K. Electrons are injected into excited quantum dot states using a graded AlGaAs injector. Direct tunneling out of the quantum dot excited states is prevented by means of a superlattice electron filter. Two midinfrared peaks are seen in the electrically pumped surface emission spectra of the device. The emission peaks are orthogonally polarized within the growth plane, indicating photon emission from intersublevel electron transitions within anisotropically shaped quantum dots.