TUNNELING EFFECTS IN LIGHT-EMITTING-DIODES BASED ON INGAN ALGAN/GAN HETEROSTRUCTURES WITH QUANTUM-WELLS/

Tunneling effects in the luminescence spectra and the electrical prope rties of blue light-emitting diodes based on InGaN/AlGaN/GaN heterostr uctures have been investigated. The tunneling radiation in the energy range 2.1-2.4 eV predominates for weak currents (<0.2 mA), and its rol e increases as the peak of the main blue band shifts into the short-wa velength region. The position (h) over bar omega(max) of the maximum i s approximately proportional to the voltage eU. The shape and intensit y of the band are described by the theory of tunneling radiation. The current-voltage characteristics for low direct currents possess a tunn eling component with exponent E-J = 130-140 meV. The distribution of e lectrically 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 energ y diagram of the structures is discussed.(1)) (C) 1997 American Instit ute of Physics. [S1063-7826(97)00311-6].