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利用金属有机物化学气相沉积技术在蓝宝石衬底(0001)面生长了InGaN/GaN多量子阱结构,并测量了其荧光(PL)光谱的峰位能量和发光效率对温度和注入载流子密度的依赖性.结果显示,该样品PL的峰位能量对温度的依赖性是“S形”的(降低-增加-降低),并且最大发光效率出现在50 K左右.前者反映了InGaN阱层中势能的非均一性和载流子复合的局域特征,后者则表明了将极低温度下的内量子效率设定为100%的传统界定方法应当被修正.进一步的研究结果显示,发光效率不仅是温度的函数,同时也是注入载流子密度的函数.为此我们对传统的基于PL光谱测量来确定某结构(或器件)内量子效率的方法进行了修正:在不同温度下测量发光效率对注入载流子密度的依赖性,并将发光效率的最大值设为内量子效率是100%,这样,其他温度点和注入载流子密度点所对应的内量子效率也就随之确定.
InGaN / GaN multi-quantum well structure was grown on the (0001) plane of sapphire substrate by metalorganic chemical vapor deposition technique and the effect of peak energy and luminous efficiency of the fluorescence (PL) spectrum on the temperature and the carrier density The results show that the temperature dependency of the peak energy of the sample PL is “S-shaped” (decrease-increase-decrease) and the maximum luminous efficiency appears at about 50 K. The former reflects the InGaN well layer The potential heterogeneity and the local characteristics of carrier recombination, the latter shows that the traditional method of defining the internal quantum efficiency at very low temperatures as 100% should be modified.Further studies show that the emission of light Efficiency is not only a function of temperature, but also a function of injected carrier density. For this reason, we modified the traditional method of determining the quantum efficiency in a structure (or device) based on PL spectroscopy measurements: measuring luminescence at different temperatures The dependence of the efficiency on the injected carrier density and the maximum luminous efficiency as the internal quantum efficiency is 100% so that the internal quantum efficiencies corresponding to the other temperature points and the point at which the carriers are injected are also determined .