Status of GaN-based green light-emitting diodes**Project supported by the Key Program of the National Natural Science Foundation of China (Grant No. 61334001), the National Natural Science Foundation of China (Grant Nos. 11364034 and 21405076), the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No. 2011BAE32B01), and the National High Technology Research

Abstract

GaN-based blue light emitting diodes (LEDs) have undergone great development in recent years, but the improvement of green LEDs is still in progress. Currently, the external quantum efficiency (EQE) of GaN-based green LEDs is typically 30%, which is much lower than that of top-level blue LEDs. The current challenge with regard to GaN-based green LEDs is to grow a high quality InGaN quantum well (QW) with low strain. Many techniques of improving efficiency are discussed, such as inserting AlGaN between the QW and the barrier, employing prestrained layers beneath the QW and growing semipolar QW. The recent progress of GaN-based green LEDs on Si substrate is also reported: high efficiency, high power green LEDs on Si substrate with 45.2% IQE at 35 A/cm2, and the relevant techniques are detailed.