This paper analyses the impact of the presence of a silicon nitride passivation layer on the thermal stability of gallium nitride LEDs. It is shown that the presence of the passivation layer can affect devices reliability during high temperature stress: identified degradation mechanisms are efficiency decrease, emission crowding and forward voltage increase. The degradation is attributed to the thermally activated diffusion of hydrogen from the passivation layer to the p-type region of the diodes: this hydrogen can bind with magnesium, thus lowering the active acceptor concentration, worsening the transport properties of the p-side GaN and ohmic contact, and devices efficiency. The activation energy of the degradation was found to be equal to 1.3 eV.
High temperature instabilities of GaN LEDs related to passivation
MENEGHINI, MATTEO;TREVISANELLO, LORENZO ROBERTO;MENEGHESSO, GAUDENZIO;ZANONI, ENRICO
2006
Abstract
This paper analyses the impact of the presence of a silicon nitride passivation layer on the thermal stability of gallium nitride LEDs. It is shown that the presence of the passivation layer can affect devices reliability during high temperature stress: identified degradation mechanisms are efficiency decrease, emission crowding and forward voltage increase. The degradation is attributed to the thermally activated diffusion of hydrogen from the passivation layer to the p-type region of the diodes: this hydrogen can bind with magnesium, thus lowering the active acceptor concentration, worsening the transport properties of the p-side GaN and ohmic contact, and devices efficiency. The activation energy of the degradation was found to be equal to 1.3 eV.
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