Luminescence spectra of blue and green light-emitting diodes based on multilayer 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 the 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)>=2.38-2.50 eV, respectively, depending on the In content in the active layer. The spectral intensity of the principal band decreases exponentially in the long-wavelength region with energy constant E-0 = 45 - 70 meV; this is described by a model that takes into account the tails of the density of states in the two-dimensional active region and the degree of filling of the tails near the band edges. At low currents radiative tunneling recombination with a voltage-dependent maximum in the spectrum is observed in the spectra of the blue diodes. A model of the energy diagram of the heterostructures is discussed. (C) 1997 American Institute of Physics.