1.  To overcome these issues, a “dual-stage MQW” structure was proposed to enhance the electron injection and improve the crystalline quality of the overlying MQW.  As an effort to do so, a triangular quantum well (TQW) structure in the InGaN/GaN MQW active region has been recently proposed to weaken the polarization field.  In this paper, we propose a LED structure, named shallow TQW structure, to improve the emission property of LED devices.

2. Experiments FIG. 1. (a) Schematic diagram of the epitaxial LEDs with the shallow QWs structure. Buffer layer ： low temperature, grown at 530 ℃ Si-doped n-GaN layer ： 3 μm, grown at 1050 ℃ Active region ： three pairs InGaN/GaN MQW (2.7 nm/7.5 nm, grown at 745 ℃ /865 ℃ ) with In% ＝ 16% in each InGaN well p-GaN layer ： 200 nm, grown at 920 ℃ Sample A ： TQW structure Sample B ： RQW structure Sample C ： without shallow QWs Shallow QWs structure ：

3. (b) Schematic band profiles of the shallow QWs structure and the active region of LEDs with shallow TQW (Sample A), (c) LEDs with shallow RQW (Sample B), and (d) conventional LEDs (Sample C). Diagram is not to scale.