Experimental Demonstration of Time-Dependent Breakdown in GaN-Based Light Emitting Diodes

This letter reports the first experimental demonstration of time-dependent breakdown in GaN-based light-emitting diodes (LEDs); based on a number of constant voltage stress tests, carried out below the breakdown limit of the devices, we show that: 1) when submitted to reverse-bias stress, the LEDs show a gradual increase in current, well correlated with an increase in the breakdown luminescence signal; 2) for sufficiently long stress times, the LEDs can reach a catastrophic (sudden) breakdown, which leads to the failure of the devices; 3) the breakdown process is time-dependent and the time to failure (TTF) has an exponential dependence on stress voltage; and 4) TTF is Weibull distributed. The results presented within this letter demonstrate that the GaN-based heterostructures can show a TDDB-like behavior, and can be useful for the interpretation of the degradation data of LEDs and HEMTs.