Changes in the luminescent and electrical properties of InGaN/AlGaN/GaN light-emitting diodes during extended operation |
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Authors: | A N Kovalev F I Manyakhin V E Kudryashov A N Turkin A É Yunovich |
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Affiliation: | (1) Moscow Institute of Steel and Alloys, 117936 Moscow, Russia;(2) M. V. Lomonosov Moscow State University, 119899 Moscow, Russia |
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Abstract: | Changes in the luminescence spectra and current-voltage and capacitance-voltage characteristics of light-emitting diodes based
on InGaN/AlGaN/GaN heterostructures were investigated as functions of operating time during extended use. Sample blue and
green light-emitting diodes with InGaN single quantum-well active layers were examined during operating times of 102−2×103 h at currents up to 80 mA. An increase in the efficiency at the working currents (15 mA) was observed in the first stage
of aging (100–800 h) followed by a decrease in the second stage. The greatest changes in the spectra were observed at low
currents (<0.15 mA). Studies of the distribution of charged acceptors in the space-charge region showed that their concentration
grows in the first stage and falls in the second. Models explaining the two stages of aging are proposed: 1) activation of
Mg acceptors as a result of destruction of residual Mg-H complexes, and 2) formation of N donor vacancies. A model of subthreshold
defect formation by hot electrons injected into the quantum wells is discussed.
Fiz. Tekh. Poluprovodn. 33, 224–232 (February 1999) |
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