Al-Rich III-Nitride Materials and Ultraviolet Light-Emitting Diodes

Abstract

Aluminum nitride (AlN) material is commonly used as a crucial template for the growth of high-quality Al-rich III-nitride materials and high-performance deep-ultraviolet light-emitting diodes (DUV LEDs). In this chapter, the heteroepitaxy of AlN film by MOVPE and the development of AlN epitaxy techniques on sapphire substrates are discussed. The structural design for efficient DUV LEDs is then introduced. Since bulk AlN substrates are a perfect candidate for AlGaN-based DUV LEDs due to similar thermal expansion coefficients and relatively small lattice mismatches, we also discussed AlN homoepitaxy, pseudomorphic AlGaN, and DUV LEDs on AlN substrates. The limited light extraction efficiency (LEE) is another obstacle for power DUV LEDs and their applications. The intrinsic Al-rich-induced optical polarization effect and related methods for improving the LEE are presented.