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Optical and Electronic Properties of InGaN/GaN Multi—Quantum—Wells Near—Ultraviolet Lighting—Emitting—Diodes Grown by Low—Pressure Metalorganic Vapour Phase Epitaxy 下载免费PDF全文
The near-ultraviolet lighting-emitting-diodes (UV-LEDs) with the InGaN/GaN multi-quantum-well (MQW) structure were grown by low-pressure metalorganic vapour phase epitaxy. The double crystal x-ray diffraction revealed a distinct second-order satellite peak. The near-ultraviolet InGaN/GaN MQW LEDs have been successfully fabricated to emit at 401.2nm with narrow FWHM of 14.3nm and the forward voltage of 3.6 V at 20 mA injection current at room temperature. With increasing forward current from l 0 mA to 50 mA, the redshift of the peak wavelength was observed due to the band-gap narrowing caused by heat generation. 相似文献
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以α-烯烃磺酸钠(AOS)为可聚合乳化剂、苯乙烯(St)为非极性单体、甲基丙烯酸甲酯(MMA)为极性单体、二乙烯基苯(DVB)为交联剂、十六烷(HD)为助稳定剂,通过细乳液聚合法制备了聚合物包覆蒽醌类染料的纳米色料。利用透射电子显微镜(TEM)、激光粒度仪(DLS)等研究了可聚合乳化剂、极性单体和交联剂的用量对纳米色料形貌的影响。结果表明:该纳米色料具有明显的核壳结构,且乳液的稳定性好。随着乳化剂用量的增加,粒子粒径变小;少量极性单体的加入有助于得到粒径分布较窄的核壳结构纳米粒子,交联剂和单体彼此极性的差异会导致粒子表面粗糙。以St为聚合单体,当DVB的质量小于St质量的30%时,能够得到结构规整的纳米粒子,超过30%时,纳米粒子表面不再光滑。而以MMA为聚合单体,当DVB的质量为MMA的8%~30%时,粒子表面均凹凸不平。 相似文献
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负载卤化镍(NiX2/HD)催化MMA的原子转移自由基聚合 总被引:1,自引:0,他引:1
以负载卤化镍(NiX2/HD)为催化剂合成聚甲基丙烯酸甲酯(PMMA),具有反应可控、后处理简单且催化剂可以反复使用的优点。研究结果表明:卤原子、催化剂、钝化剂的类型和含量、反应温度等条件对该体系的聚合速率及可控性有重要影响。在相同条件下,NiCl2较NiBr2的催化速率快;钝化剂卤化铜/三-(N,N-二甲基氨基乙基)胺(CuX2/Me6TREN)对聚合产物分子量分布的可控性要优于卤化铁/三-(N,N-二甲基氨基乙基)胺(FeX3/Me6TREN);增大钝化剂的含量,聚合速率降低,且含量为1%时聚合的可控性较好;温度升高聚合速率加快,分子量分布指数(PDI)增大。顺磁共振检测中观察到钝化剂中过渡金属的化合价发生改变。 相似文献
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The effects of dopants on the defects of GaN films were investigated by using different methods, such as wet,etching of pits, x-ray dit~action and photoluminescence (PL). Three kinds of the samples were prepared with different dopants, that is, nominally undoped, Si-doped and Mg-doped GaN films. It was found that the lowest density of the, etched pit was existed in the nominally undoped GaN, while the highest in the Mg-doped sample.The effects of the dopants on the, etching pits were discussed. 相似文献
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Influence of Growth Temperature and Trimethylindium Flow of InGaN Wells on Optical Properties of InGaN Multiple Quantum-Well Violet Light-Emitting Diodes 下载免费PDF全文
An InGaN multiple-quantum-well (MQW) violet-light-emitting diode (LED) is grown by low-pressure metalorganic chemical vapour deposition. It is found that photoluminescence wavelength of the InGaN MQW violet LED is lengthened with increasing growth temperature and with the increasing trimethylindium flow of the InGaN wells. The electroluminescence peak wavelength of the violet LED are about 401 nm with full width at half maximum of 14nm, and the output power in injection current of 2OmA at room temperature is 4.1mW. 相似文献