Spectra and Quantum Efficiency of Light-Emitting Diodes Based on GaN Heterostructures with Quantum Wells
1999; Wiley; Volume: 176; Issue: 1 Linguagem: Inglês
10.1002/(sici)1521-396x(199911)176
ISSN1521-396X
AutoresA. É. Yunovich, V. E. Kudryashov, S. S. Mamakin, A. N. Turkin, A. N. Kovalev, F. I. Manyakhin,
Tópico(s)Photocathodes and Microchannel Plates
ResumoSpectra and quantum efficiency ηe of green LEDs based on heterostructures InGaN/AlGaN/GaN with multiple quantum wells were studied at currents J = 10—6 to 10—1 A. Minor differences in ηe (of ±10% at J ≈︂ 10 mA) are caused by sufficiently different distributions of effective charges in the space charge regions and the different role of tunnel component of J at low voltages. The main peak in the spectra at low J (ħωmax = 2.35 to 2.36 eV) does not depend on the voltage. At J > 0.2 mA the spectral band is shifted with J (ħωmax = 2.36 to 2.52 eV). The origin of the “standing” and “moving” bands is discussed. The model of 2D structures with band tails describes the spectral form with four fitting parameters rather well. A tunnel radiation band is revealed in the long wavelength range (1.93 to 2.03 eV) in the LEDs with a thin space charge region (w ≤ 120 nm). The dependence of ηe on J has a maximum which correlates with the fitting parameters and J(V) and NA(w) curves. Possible microscopic and macroscopic inhomogeneities in the structures are discussed.
Referência(s)