| â…¢-â…¤compound has been considered as the third generation semiconductor, and because nitride compound has many advantages, such as wide bandgap, high electron mobility, high luminous efficiency and high frequency, it can be widely used in blue and violet light emitting diodes(LED) and laser diodes. As the technology of luminescent materials developing, LED has been applied in traffic lights, streetlights and large area display industries, because of long life time, high efficiency and high luminance, especially the rapid develop of Ga N-based LED, white lights and full color display based on blue LED have become research hotspot. LED has the trend of replace incandescent light, this means the time of semiconductor lighting will come soon. But yet Ga N-based LED has two issues needed to be solve, the frist one is external quantum efficiency decrease at high injection current density, which called efficiency droop, and the second one is poor light extraction efficiency, which caused by the high index of refraction of Ga N.The main contents of this work include:1. Effect on the photoelectric properties of LED using different nucleartion layer. Three samples were grown, include Ga N and Al N nucleation layer grown by metalorganic chemical vapor deposition(MOCVD) and Al N nucleation layer grown by physical vapor deposition(PVD). The results found out Ga N grown on PVD Al N nucleation layer has the best crystal quality, expecially(002), full width at half maximum(FWHM) of the rocking curce is under 200 arcsec. All three samples have good diode characteristic, under the same voltage the sample grown on PVD nucleation layer has higher current than the other two samples, and the leakage current is the smallest at-10 V. Also the most important is the light output power increased a lot.2. Research of different quantum well thichness on LED. Quantum well thickness change from 2.4 nm to 3.6 nm, after the measurement of XRD, indium composition is same for all the samples, and the thickness is in accordance with the expectation. The exciton location effect is increased, when quantum well thickness increases from 2.4 nm to 2.7 nm, however the exciton location effect is decreased with the further increase of quantum well thickness. The wavelength becomes red shift with the increase of well thickness which due to the larger quantum confined Stark effect(QCSE). And turns out that efficiency droop is related with quantum well thickness, the thicker the quantum well is, the more carriers the quantum well holds.3. Effect of pre-TMIn on blue and green LED. Pre-TMIn treatment will not change the indium composition and the thickness of the quantum well, but will increase the In-rich regions, which will lead to redshift of the wavelength, and redshift become larger with pre-TMIn time increase. Pre-TMIn treatment will not chang the I-V characteristic, but can improve efficiency droop of the blue LED.4. Improve light extraction efficiency with Zn O nanorod. Zn O nanorod was grown by solution method. With changing the concentration of the reaction source in growth solution, we can grow different morphology of Zn O nanorod, and research the effect of different morphology on the light extraction efficiency. Zn O nanorod was grown well-aligned along c-axis, the concentration of ammonia and Zn2+ will change the morphology of nanorod, such as the length, diameter and the density. After grown Zn O nanorod on the LED, the light extraction efficiency was improved a lot, and it will not affect on the electrical properties and the luminous stability.
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