Effect of long-term aging on series resistance and junction conductivity of high-power InGaN light-emitting diodes

Abstract

The forward voltage, series resistance, and junction conductivity of commercial high-power InGaN light-emitting diodes (LEDs) were investigated as a function of aging time. A gradual decrease of series resistance with a rate of about –1%/1000 h was revealed in InGaN LEDs within first ∼9,600 hours of aging under ordinary conditions (nominal forward current 350 mA, junction temperature 350 K), whereas the characteristic energy of tunnel injection exhibited a decrease with a rate of about –0.1%/1000 h. The observed aging effects were attributed to continuous post-fabrication self-annealing of the p-type cladding layer and to the variation of the localized-state density in the active layer of the LED chips.
Keywords: aging, high-power LED, series resistance, junction conductivity
PACS: 81.40.Cd, 85.60.Bt, 85.60.Jb, 84.37.+q, 73.40.Kp