LUMINESCENCE SPECTRA OF BLUE AND GREEN LIGHT-EMITTING-DIODES BASED ONMULTILAYER INGAN ALGAN/GAN HETEROSTRUCTURES WITH QUANTUM-WELLS/

The luminescence spectra of blue and green light-emitting diodes based InxGa1-xN/AlyGa1-xN/GaN heterostructures with a thin (2-3 nm) InxGa1- xN active layer have been investigated in the temperature and current intervals 100-300 K and J = 0.01-20 mA, respectively. The spectra of t he blue and green light-emitting diodes have maxima in the interavals <(h)over bar omega(max)>=2.55-2.75 eV and <(h)over bar omega(max)>=2.3 8-2.50 eV, respectively, depending on the In content in the active lay er. The spectral intensity of the principal band decreases exponential ly in the long-wavelength region with energy constant E-0 = 45 - 70 me V; this is described by a model that takes into account the tails of t he density of states in the two-dimensional active region and the degr ee of filling of the tails near the band edges. At low currents radiat ive tunneling recombination with a voltage-dependent maximum in the sp ectrum is observed in the spectra of the blue diodes. A model of the e nergy diagram of the heterostructures is discussed. (C) 1997 American Institute of Physics.