Factors Affecting Surface Plasmon Coupling of Quantum Wells in Nitride-Based LEDs: A Review of the Recent Advances

Abstract

Surface plasmon (SP)-enhanced quantum-well (QW) LEDs have proved their potential in replacing conventional lighting devices for their high-performance capabilities in ultraviolet (UV), blue and green spectral ranges. The SP-enhanced QW-LEDs have applications in light emission enhancement, light polarization, color conversion, and speed modulation. The electric field of the plasmonic mode of a metal couples with the exciton energy of QWs in resonance results in efficiency enhancement to several folds. The strength of the SP–QW coupling is mainly influenced by the type of metal used for SP enhancement, the metal nanostructure geometry, and the penetration depth of the SP fringing field in the p-GaN. The use of an appropriate dielectric interlayer between the metal and the p-GaN allows further control over SP resonance with QW emission wavelength. The penetration depth defines the p-GaN thickness and the QW period number for effective SP–QW coupling. The optimization of these parameters is key to achieve high efficiencies in SP-enhanced QW-LEDs for various applications. This review explains the SP enhancement mechanism and the key challenges facing the SP enhancement of QW-LEDs. The main factors that affect the SP–QW coupling have been explained in detail based on recent reports devoted to this field.

Surface Plasmon Enhancement of an InGaN Quantum Well Using Nanoparticles Made of Different Metals and Their Combinations

“…It has been found that SP enhancement is rather a combined effect of absorption, scattering, scattering-to-extinction ratio, and field enhancement [ 3 , 22 ]. SP enhancement in LEDs depends on many factors such as metal type, geometry and size distribution of NPs, QW period number, QW emission wavelength, and GaN thickness [ 23 ].…”

Factors Affecting Terahertz Emission from InGaN Quantum Wells under Ultrafast Excitation

“…QCSE is the band-structure tilt in QWs due to the strong built-in piezoelectric feld [48][49][50][51]. It leads to low optical transition energy and poor recombination efciency in QW-LEDs as the wave function overlap decreases under the infuence of this feld [25,[52][53][54][55][56][57]. Tis built-in feld however plays a central role in terahertz generation upon ultrafast excitation of InGaN/ GaN QWs [33].…”

Performance Enhancement of InGaN Light-Emitting Diodes with InGaN/GaN/InGaN Triangular Barriers

“…Lately, the weak hole injection and serious electron leakage in III-nitride LEDs are frequently mentioned and are believed that may play essential roles in their efficiency droop. [4][5][6][7] It is well known that the holes in III-nitride materials have a larger effective mass and smaller mobility than that of the electrons. In addition, Mg as an acceptor in III-nitride materials has a high ionization activation energy, which limits the effective hole concentration in p-GaN.…”