Role of V-defect density on the performance of III-nitride green LEDs on sapphire substrates

In this study, we experimentally investigated the role of V-defect density on the performance of green III-nitride LEDs grown on sapphire substrates by metalorganic chemical vapor deposition. We systematically varied the threading dislocation (TD) density from 4 x 10(8) to 1 x 10(9) cm(-2) by changing the V/III ratio during initial high temperature GaN growth. A 30-period InGaN/GaN superlattice promoted V-defect formation and growth at TDs, where the density of V-defects was correlated to the TD density. By interrupting the LED growth and examining the surface of the active region, we quantified the average size and density of V-defects. In a series of LEDs, we measured a systematic decrease in forward voltage (V-F) with V-defect density. At a V-defect density of 5.0 x 10(8) cm(-2) and TD density of 1 x 10(9) cm(-2), green LED devices were demonstrated with lambda = 523 nm and V-F = 2.94 V at 20 A cm(-2). These results highlight the potential of using V-defect engineering to achieve low V-F long wavelength LEDs on sapphire substrates, where opening of remaining threading dislocations into V-defects presents an opportunity for further V-F reduction.

Automated summary

The role of V-defect density on the performance of green III-nitride LEDs grown on sapphire substrates was experimentally investigated in this study. Results showed that V-defect engineering has the potential to achieve low forward voltage and long wavelength LEDs on sapphire substrates.