Degradation of (InAlGa)N-based UV-B light emitting diodes stressed by current and temperature

作者：Glaab Johannes^*; Ploch Christian; Kelz Rico; Stoelmacker Christoph; Lapeyrade Mickael; Ploch Neysha Lobo; Rass Jens; Kolbe Tim; Einfeldt Sven; Mehnke Frank; Kuhn Christian; Wernicke Tim; Weyers Markus; Kneissl Michael

来源：Journal of Applied Physics, 2015, 118(9): 094504.

DOI：10.1063/1.4929656

The degradation of the electrical and optical properties of (InAlGa) N-based multiple quantum well light emitting diodes (LEDs) emitting near 308 nm under different stress conditions has been studied. LEDs with different emission areas were operated at room temperature and at constant current densities of 75 A/cm(2), 150 A/cm(2), and 225 A/cm(2). In addition, the heat sink temperature was varied between 15 degrees C and 80 degrees C. Two main modes for the reduction of the optical power were found, which dominate at different times of operation: (1) Within the first 100 h, a fast drop of the optical power is observed scaling exponentially with the temperature and having an activation energy of about 0.13 eV. The drop in optical power is accompanied by changes of the currentvoltage (I-V) characteristic. (2) For operation times beyond 100 h, the optical power decreases slowly which can be reasonably described by a square root time dependence. Here, the degradation rate depends on the current density, rather than the current. Again, the rate of optical power reduction of the second mode depends exponentially on the temperature with an activation energy of about 0.21 eV. The drop in the optical power is accompanied by an increased reverse-bias leakage current.

• 出版日期2015-9-7