Photoluminescence, Thermal Transport, and Breakdown in Joule-Heated GaN Nanowires

Thermal transport and breakdown in Joule-heated GaN nanowires is investigated using a combination of microphotoluminescence and in situ TEM characterization. The thermal conductivity of the nanowires is estimated to be <80 W/m.K, which is substantially below the bulk GaN value. Catastrophic breakdown in individual nanowires is observed to occur at a maximum temperature of approximately 1000 K, and nanowire morphology near the breakdown region indicates that failure occurs via thermal decomposition, a conclusion that is validated by in situ TEM images obtained during the failure process.