Electroluminescence from isolated single indium gallium nitride quantum dots up to 150 K

We present light emitting diode structures with InGaN quantum dots (QDs) as active material grown by metal-organic vapor-phase epitaxy. The devices reveal a threshold voltage of 3.15 V at room temperature, or 8.8 V at 4K. respectively. At room temperature, the electroluminescence intensity is still as high as 28% of the intensity at 4K, the emission covering the spectral region from 2.3 to 2.7 eV at 4K (2.2-2.6 eV at 300K). Electrically driven luminescence from spectrally isolated single InGaN QDs emitting in the green spectral region is demonstrated with a thermal stability of up to 150K. These results are an important step towards applications like electrically driven single photon emitters at elevated temperatures, which are desirable as a basis for communication techniques incorporating plastic optical fibers as well as for modern concepts of free space quantum cryptography. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim