Efficiency enhancement of green light emitting diodes by improving the uniformity of embedded quantum dots in multiple quantum wells through working pressure control

InGaN/GaN multiple-quantum-wells (MQWs) in green light emitting diodes (G-LEDs) containing embedded quantum dots (QDs) inside or extruded 3D-like QDs with various size distributions produced via spinodal decomposition are grown by metal-organic chemical vapor deposition. The average size of QDs changes from 3.05 nm to 2.40 nm as the working pressure decreases from 500 torr to 300 torr. The growth mechanism of QDs is discussed. The photoluminescence and electroluminescence results show that smaller and more uniform embedded QDs can improve recombination efficiency, and thus achieve higher peak intensity with smaller peak broadening. More importantly, this work demonstrates that the embedded QDs undergo higher strain relaxation, with a smaller piezoelectric field and better droop performance. Accordingly, the performance of external quantum efficiency is enhanced, leading to a 20% increase in light output power in lamp-form package LEDs. (C) 2016 Published by Elsevier B.V.