Dependence of radiative efficiency and deep level defect incorporation on threading dislocation density for InGaN/GaN light emitting diodes

The influence of threading dislocation (TD) density on electroluminescence and deep level defect incorporation in the multi-quantum well regions of InGaN/GaN light emitting diodes (LEDs) was investigated. LED efficiency increased with decreasing TD density. To elucidate the impact of TD density on deep level defect incorporation and resulting radiative efficiency, deep level optical spectroscopy and lighted capacitance voltage measurements were applied to the LEDs. Interestingly, the concentration of all observed deep levels decreased with TD density reduction, but their concentration also varied strongly with depth in the multi-quantum well region. These trends indicate that (1) TDs strongly influence point defect incorporation in InGaN/GaN LEDs and (2) TDs, possibly in conjunction with point defects, are detrimental to LED efficiency.