Browsing by Author "Santiago, Svette Reina Merden"

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Enhanced Performance of GaN-based Ultraviolet Light Emitting Diodes by Photon Recycling Using Graphene Quantum Dots
(2017-08-02)
Lin, Tzu-Neng
;
Santiago, Svette Reina Merden
;
Yuan, Chi-Tsu
;
Chiu, Kuo-Pin
;
Shen, Ji-Lin
ablation. The synthesized GQDs can improve the optical and electrical properties of InGaN/InAlGaN UV light emitting diodes (LEDs) remarkably. An enhancement of electroluminescence and a decrease of series resistance of LEDs were observed after incorporation of GQDs on the LED surface. As the GQD concentration is increased, the emitted light (series resistance) in the LED increases (decreases) accordingly. The light output power achieved a maximum increase as high as 71% after introducing GQDs with the concentration of 0.9 mg/ml. The improved performance of LEDs after the introduction of GQDs is explained by the photon recycling through the light extraction from the waveguide mode and the carrier transfer from GQDs to the active layer.
Tunnel injection from WS2 quantum dots to InGaN/GaN quantum wells
(2018-01-01)
Santiago, Svette Reina Merden
;
Caigas, Septem P.
;
Lin, Tzu-Neng
;
Yuan, Chi-Tsu
;
Shen, Ji-Lin
We propose a tunnel-injection structure, in which WS2 quantum dots (QDs) act as the injector and InGaN/GaN quantum wells (QWs) act as the light emitters. Such a structure with different barrier thicknesses has been characterized using steady-state and time-resolved photoluminescence (PL). A simultaneous enhancement of the PL intensity and PL decay time for the InGaN QW were observed after transfer of charge carriers from the WS2-QD injector to the InGaN-QW emitter. The tunneling time has been extracted from the time-resolved PL, which increases as the barrier thickness is increased. The dependence of the tunneling time on the barrier thickness is in good agreement with the prediction of the semiclassical Wentzel-Kramers-Brillouin model, confirming the mechanism of the tunnel injection between WS2 QDs and InGaN QWs.
Tunnel injection from WS2 quantum dots to InGaN/GaN quantum wells (vol 8, pg 15399, 2018)
(2018-01-01)
Santiago, Svette Reina Merden
;
Caigas, Septem P.
;
Lin, Tzu-Neng
;
Yuan, Chi-Tsu
;
Shen, Ji-Lin