LED materials: Epitaxy and quantum well structures

Abstract

This chapter describes how, in order to achieve low droop and high-efficiency light-emitting diodes (LEDs), we investigated the following multiple quantum wells (MQWs) and electron-blocking layer (EBL) design to enhance our LED devices: Graded-thickness multiple quantum wells (GQWs), graded-composition multiple quantum barriers (GQBs), selectively graded-composition multiple quantum barriers (SGQBs), and graded-composition electron-blocking layer (GEBL). Besides, the crystal quality of the epitaxial layer was enhanced by introducing freestanding GaN substrate for the epitaxial growth of III-nitride epilayer. On the other hand, in recent years, the epitaxial growth of GaN-based materials on Si substrate has a great potential for applications in low-cost and high-efficiency LEDs. Hence, the properties of GaN-based LEDs on Si will also be described in this chapter.