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

Mid-infrared electroluminescence and photoluminescence due to transitions between states in InAs self-assembled quantum dots has been measured from both p-n junctions and unipolar (n-doped) tunneling structures. Low-temperature (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 devices peaks near the low-energy cutoff of our optical system (about 80 meV). The electroluminescence from the unipolar devices is also broad, but peaks at an energy of about 140 meV, while photoluminescence on the same structure is similar to the p-n junction electroluminescence. The electroluminescence 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/cm².