Mid-infrared electroluminescence from InAs quantum dots in p-n junctions and unipolar tunneling structures

Mid-infrared electroluminescence and photoluminescence due to transitions b etween states in InAs self-assembled quantum dots has been measured from bo th p-n junctions and unipolar (n-doped) tunneling structures. Low-temperatu re (77 K) luminescence was detected from single layers of quantum dots. The mid-infrared from the quantum dots is broad and for the p-n junction devic es peaks near the low-energy cutoff of our optical system (about 80 meV). T he electroluminescence from the unipolar devices is also broad, but peaks a t an energy of about 140 meV, while photoluminescence on the same structure is similar to the p-n junction electroluminescence. The electroluminescenc e from the p-n junction devices is more intense than from the unipolar ones , and begins to saturate at current densities as low as 20 mA/cm(2).