Jan 21, 2019

Anelasticity of GaN Epitaxial Layer in GaN LED

In this work, the anelasticity of the GaN layer in the GaN light-emitting-diode device was studied. The present results show that the forward-voltage of GaN LED increases with time, as the GaN light-emitting-diode was maintained at a constant temperature of 100 °C. We found that the increase of the forward-voltage with time attributes to the delay-response of the piezoelectric fields (internal electrical fields in GaN LED device). And, the delay-response of the internal electrical fields with time is caused by the anelasticity (time-dependent strain) of the GaN layer. Therefore, using the correlation of strain-piezoelectric-forward voltage, a plot of thermal strain of the GaN layer against time can be obtained by measuring the forward-voltage of the studied GaN LED against time. With the curves of the thermal strain of GaN epi-layers versus time, the anelasticity of the GaN compound can be studied. The key anelasticity parameter, characteristic relaxation time, of the GaN is defined to be 2623.76 min in this work.


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