Taib, M lkram Md and Zamat, N. and Hassan, Z.
(2016)
Closing Green Gap in LEOs Technology: Chal lenges and Future Solutions.
In: 3rd Meeting of Malaysia Nitrides Research Group (MNRG 2016).
Abstract
By 2020, demand would be strong in Malaysia lighting market, witnessing rapid growth residing in applications such as commercial/industrial lig hting. horticultural lighting and medical/health care ligh ting. Great progress on blue LE Ds based on 111-V nitrides has been acllteved . with their efficiency is more than 80%. Nonetheless, this is not the case for longer wavelength em ission LEDs . which covers visible energy spectrum from green to red . The ex ternal quantum efficiency (EQE) of those devices is reported to degrade significantly with increasing current. Suct1 problem 1s related to t1tgt1 droop efficiency and trlis phenomenon is known as 'Green gap' In principle . longer emtssion wavelength LEDs requires more indium composition in ln,Ga ,., N quantum wells . Nevertheless , growing ln,Ga ,_,N materials with high indium composition is diffi cult due to indium decomposition issue. which always leads to significa nt reduction of internal quantum efficiency (IOE) and subsequently EQE of the LEDs. To overcome this issue, several novel methods have been proposed in literature and will be discussed in the talk. Furtherm ore. major challenge to increase IQE/EOE of longer wavelength emission LEDs is quantumconfinement Stark effect (QCSE), which becomes more sign ificant 111 ln,Ga ,_,N materials with high indium composition. The effect reduces wavefunction of electrons and holes. resulting low internal radiative quantum effic ie ncy of LEOs. Growing longer emission waveleng h LEOs on semipolar and nonpolar GaN substra te is one of ways to eliminate the OCSE phenomena . but is this techn ique desirable from industrial practica l point of view? Towards th e end of the talk , future plan to develop longer emission wavelength LEDs at INOR. USM will be proposed . Discussion on design structure of th e LEDs, with substrate choice in order to suppress the droop efficiency of th e LEDs will be presented
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