Aging Mechanisms of InGaN/AlGaN/GaN Light-Emitting Diodes Operating at High Currents

Abstract

Changes of luminescence spectra and electrical properties of light-emitting diodes (LED's) based on InGaN/AlGaN/GaN heterostructures were investigated over a long period of operation. Blue and green LED's with InGaN single quantum wells were studied at currents up to 80 mA for 10 2 -2.10 3 hours. An increase of luminescence intensity at operating currents of 15 mA was detected at the 1st stage of aging (100-800 hours) and a slow fall was detected in the 2nd stage. Greater changes of spectra were observed at low currents (< 0.15 mA). A study of charged acceptor distribution in the space charge region has shown that at the 1st stage their concentration grows, and in the 2nd stage, it falls. The models for the two stages are proposed: 1) activation of Mg due to destruction of residual Mg-H complexes; 2) formation of donor vacancies N. A model of defect formation by hot electrons injected into the quantum well is discussed.

Simulation of visible and ultra-violet group-III nitride light emitting diodes

“…Comparison of the I-V characteristic of the SQW LED measured on various samples [27,83] with those calculated for the contact area A = 10 À3 mm 2 and the serial resistance R s = 20 X is presented in Fig. 6.…”

Peculiarities of defect generation under injection current in LEDs based on group‐III nitride3N nanostructures

“…Several mechanisms of defects generation have been proposed that include broken bonds of Mg-H and Ga-N pairs of atoms in the high electrical field of a heterojunction [2], activation of the closed core screw dislocations with the help of nitrogen vacancies [3], and defect generation under hot-electron injection [4]. Migration of Alatoms (for UV LEDs) and of Ga-and In-atoms (for blue LEDs) have been also considered [1,3,5].…”

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

“…The decrease in series resistance could be attributed to continuous annealing of the p cladding layer in the light-emitting structure. Such a post-fabrication self-annealing can result in a higher density of holes due to the instability of residual Mg-H complexes [21][22][23] and might be more pronounced in high-power LEDs operating at increased junction temperatures. However, the junction temperature of 350 K is too low to invoke conventional breakdown of the Mg-H complexes, which are known to dissociate at about 1000 K [24].…”