Tunneling effects in light-emitting diodes based on InGaN/AlGaN/GaN heterostructures with quantum wells

Tunneling effects in the luminescence spectra and the electrical properties of blue light-emitting diodes based on InGaN/AlGaN/GaN heterostructures have been investigated. The tunneling radiation in the energy range 2.1-2.4 eV predominates for weak currents (<0.2 mA), and its role increases as the peak of the main blue band shifts into the short-wavelength region. The position (h) over bar omega(max) of the maximum is approximately proportional to the voltage eU. The shape and intensity of the band are described by the theory of tunneling radiation. The current-voltage characteristics for low direct currents possess a tunneling component with exponent E-J = 130-140 meV. The distribution of electrically active centers reveals extended, compensated layers in the n- and p-type regions, adjoining the active layer, and indicates the presence of charged walls at the boundaries of the heterojunctions. A strong electric field is present in the InGaN active region. The energy diagram of the structures is discussed.(1)) (C) 1997 American Institute of Physics. [S1063-7826(97)00311-6].