Curves showing luminous efficiencies as a function of operating currents after aging for different periods at temperatures: (a) 60 °C; (b) 90 °C; (c)120 °C; (d) 150 °C.
Curves showing the normalized luminous efficiency as a function of aging time at different measuring currents under aging conditions: (a) 60 °C, (b) 150 °C, where efficiencies are normalized by the corresponding initial values before stress.
I-V characteristics of LED chips after aging for different periods at temperatures: (a) 60 °C, (b) 150 °C.
Schematic drawing of an LED chip being eutectic bonded on a MCPCB.
Scanning acoustic image of the LED sample after aging at 150 °C for 463 h.
Reflectivity of the fabricated Ag film: before aging and after aging for 463 h at 150 °C.
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