Recent Developments in InGaN-Based Blue Leds and Lds

Abstract

UV/blue/green/amber InGaN quantum-well structure light-emitting diodes with an external quantum efficiency of 7.5%, 11.2%, 11.6%, and 3.3% were developed. The localization in the InGaN well layer induced by the In composition fluctuations seems to be a key role of the high efficiency of those InGaN-based light-emitting diodes. When the electrons and holes are injected into the InGaN active layer of the light-emitting diodes, these carriers are captured by the localized energy states before they are captured by the nonradiative recombination centers caused by the large number of threading dislocations. InGaN multi-quantum-well structure laser diodes ' with modulation doped strained-layer superlattice cladding layers grown on the epitaxially lateral overgrown GaN substrate were demonstrated to have an estimated lifetime of more than 10000 hours under-room temperature continuous-wave operation. When the laser diode was formed on the GaN layer above the SiO2 mask region without any threading dislocations, the threshold current density was as low as 2.7 kA cm -2 . When the laser diode was formed on the window region with the high threading dislocation density, the threshold current density was as high as 4.5 to 9 kA cm -2 . A leakage current due to a large number of threading dislocations caused the high threshold current density on the window region.

Production and luminescent properties of CdSe and CdS nanoparticle–polymer composites

“…Traditionally, white light has been generated using tungsten filament bulbs or fluorescent tubes. A recent development that promises to provide white light with improved energy conversion has been the introduction of lights based on blue light emitting diodes (LEDs) [3][4][5][6]. The blue light impinges upon a YAG crystal and the fluorescence from the crystal approximates to white light, in that it provides a broad emission centred on 550 nm.…”

First‐principle study on crystal growth of Ga and N layers on GaN substrate

“…In this study, we have simulated some kind of initial states of GaN surface growth from the viewpoint of metal-organic chemical-vapor deposition (MOCVD). It is clarified that NH 3 molecules and N radicals can not fully terminate the (0001) Ga surface, and that chemical reactions between trimethylgallium and NH 3 in gas-phase is desirable to some extent because the products which contain GaN cores are immediately stabilized on the GaN(0001) surface.1 Introduction III-V nitride semiconductors have attracted much attention to be applied to several devices, light-emitting diodes, laser diodes, and photo detectors, during these 20 years [1,2]. A lot of trials and errors have been examined to fabricate GaN single crystal to satisfy the industrial requirements, although eliminating the defect concentrations is not easy.…”

Quantum chemical study on substituent effect of gas‐phase reactions in III–V nitride semiconductor crystal growth

“…Wide-band-gap III-V nitride semiconductors attract much attention for application to blue light emitting diodes (LEDs) and laser diodes (LDs) [1,2]. Rapid progress in the metal-organic vapour phase epitaxy (MOVPE) method makes it possible to grow GaN and InGaN crystals at atmospheric pressure [1 -8].…”