Regensburg 2002 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 44: GaN II

HL 44.5: Vortrag

Freitag, 15. März 2002, 11:45–12:00, H15

Accelerated Lifetime Testing of GaInN/GaN Light Emitting Diodes — •Heinz-Christoph Neitzert, Manuela Ferrara, and Elena Salurso — Universita di Salerno, DIIIE, Fisciano(SA), Italy

III-V nitride compound semiconductor, that cover a wide range of emitting wavelengths from the red to UV-wavelengths, have been successfully used for highly efficient LED?s and lasers [1], however there are still concerns regarding the device lifetime, for example due to the lattice mismatch between sapphire substrates and GaN layers and ? as compared to other LED?s, ESD sensitivity is still an importabt reliability issue [2]. We developed two easy to install LED degradation monitoring systems and performed comparative studies of accelerated lifetime tests on two families of GaInN/GaN LED?s, emitting at 430nm and 470nm, both under high current stress and under current pulse stress conditions. In both cases we found that the current-voltage (IV) caracteristics of the LED?s was rather insensitive to device degradation. However, we found a good correlation between the decrease of the optical emitted power and changes in the optical pulses decay time, as measured during pulsed degradation with 500mA pulses with stepwise increasing pulse length. Changes in the electroluminescence decay may therefore be used as an alternative method to detect early device degradation that is easier to perform than alternative sensitive methods as the measurement of the noise power spectrum [3]. [1]T.Mukai, K.Takekawa, and S.Nakamura, Jpn.J.Appl.Phys 37, L839 (1998) [2]D.L.Barton, M.Osinski, P.Perlin, P.G.Eliseev and J. Lee, Microel. Rel. 39, 1220 (1999) [3]D. Ursutiu and B.K.Jones, Semicond. Sci. Technol. 11, 1133 (1996)