Impact ionization luminescence of InGaN/AlGaN/GaN p-n-heterostructures

The luminescence spectra of InGaN/AlGaN/GaN p-n heterostructures with reverse bias sufficient for impact ionization are investigated. The injection luminescence of light-emitting diodes with such structures was examined earlier. A strong electric field is present in the InGaN active layer of the heterostructures, and for small reverse bias the tunneling component of the current predominates. Avalanche breakdown commences at voltages V-th>8-10 V, i.e., similar to 3E(g), (E-g is the width of the band gap) in the absence of lightly doped structures. The luminescence spectra have a short-wavelength edge corresponding to the width of the GaN band gap (3.40 eV) and maxima in the region 2.60-2.80 eV corresponding to the maxima of the injection luminescence spectra in the active layer. The long-wavelength edge of the spectra in the region 1.7-1.8 eV may be associated with deep recombination levels. Mechanisms of recombination of the hot electron-hole plasma in the strong electric fields of the p-n heterostructures are discussed. (C) 1998 American Institute of Physics.