We introduce a structure of multi-quantum barriers (MQBs) into the multi-quantum well (MQW) heterostructures to
improve the performance in light-emitting diodes. The InGaN/GaN MQW LEDs with and without MQBs were prepared
by metal-organic vapor phase epitaxy system. The electroluminescence measurements were carried out over a
temperature range from 20 to 300 K and an injection current level from 10 to 100 mA. According to the experimental
results of the InGaN/GaN MQW LEDs, we observe the enhancement of carrier confinement in the active layer and the
inhibited carrier leakage over the barrier to the p-GaN regions for the sample with MQBs, which we attribute to the
increase of effective barrier heights due to the quantum interference of the electrons within MQBs. In addition, the
variations of electroluminescence external quantum efficiency as a function of injection current at various temperatures
are also obtained for the samples. It is observed that the sample possessing MQBs exhibit less sensitive temperature
dependence and indeed improve the radiative efficiency.
A novel light-emitting diode backlight module applied in liquid crystal displays is demonstrated. With microgrooves on
the bottom surface and diffusive dots on the upper surface of the light guide plate (LGP), most of the incident backlight
is utilized effectively and the dispersion of light is decreased obviously. The design procedure of optimization for the
backlight module is accomplished by the TracePro optical simulation software. Relationship between the dimensions of
microgrooves and diffusive dots are investigated and discussed in detail. By using the structure of microgrooves and
diffusive dots on the LGP, the incident light satisfies the total internal reflection conditions and reflects from the bottom
surface then spread by the diffusive dots. Compared to the conventional backlight devices, the light uniformity and light
intensity for the LGP are improved by our design.
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