GaN基紫外LED多量子阱势阱层材料生长条件的研究

发布时间：2018-04-15 18:02

  本文选题：氮化镓 + 发光二极管　； 参考：《西安电子科技大学》2015年硕士论文

【摘要】：GaN基紫外LED由于其效率高、耗能少、坚固耐用以及安全环保等优势,在工业及日常生活中得到了广泛应用。但是,目前量子阱结构的GaN基紫外LED发光效率仍然非常低,这严重的限制了紫外LED的发展。所以,如何提高紫外LED的发光效率,尤其是其内量子效率已经成为国内外各机构的研究热点。本文的目的就是通过提升量子阱势阱层材料生长质量来提高紫外LED器件的发光效率。本文介绍了LED器件的基本特性,对提高LED发光效率的方法进行了比较,并给出了势阱层材料In GaN的生长模型,根据生长模型对势阱层材料的生长温度和掺In流量进行了优化实验,通过对实验样品的测试与分析得出结论。以下是本文取得的主要成果:针对势阱层材料生长温度对材料质量的影响,本文首先进行了生长温度升高序列实验,并对样品进行了材料和器件的测试。测试结果表明,随着生长温度的提高,材料中位错密度有所下降,量子阱光致发光强度随之增大。测试结果还表明,在掺In流量较低时,温度较小幅度的改变对量子阱中In组分的影响不大。通过对最终器件的电学特性的测试发现,提升势阱层材料生长温度对LED发光效率产生了积极的影响,器件由于位错而导致的漏电现象也得到一定程度改善。由于温度调整实验中掺In流量较小,所以本文针对性的进行了提升掺In流量实验。通过对实验样品的测试与分析可知,随着掺In流量的增大,量子阱中In组分逐渐增大。掺In流量少量增加时,材料生长质量会有较小幅度改善,但是当掺In流量增大到一定值时,位错密度却大幅度提升。同时发现掺In流量过大还会导致量子阱光致发光强度降低。通过对量子阱能带结构的分析发现,提升掺In流量会增大阱垒层材料间应力,量子斯塔克效应会更加显著。最终器件测试结果表明,提升掺In流量会使器件发光波长增大,发光效率提高。虽然提升掺In流量能够提升器件发光效率,但是发光波长也会增大。因此,针对这个问题本文进行了第三组实验,同时调整生长温度和掺In流量,得到不同材料生长条件下发光波长相同的器件。对器件测试结果的分析表明,势阱层材料生长温度为810℃,掺In流量为基础流量的15%时得到的样品有着较好的材料质量和器件电特性。最终得到的器件在发光波长为363.82nm时,发光功率为43.33mW,比基础程序得到器件的发光效率提升了22.5%,这表明了本文通过提升势阱层材料生长质量来提高紫外LED发光效率是非常有效的。
[Abstract]:GaN based UV LED has been widely used in industry and daily life due to its high efficiency, low energy consumption, durability, safety and environmental protection.However, the luminescence efficiency of GaN based UV LED with quantum well structure is still very low, which seriously limits the development of UV LED.Therefore, how to improve the luminescence efficiency of UV LED, especially its quantum efficiency, has become a hot research topic in domestic and foreign institutions.The aim of this paper is to improve the luminescence efficiency of ultraviolet LED devices by improving the growth quality of quantum well potential well materials.This paper introduces the basic characteristics of LED devices, compares the methods of improving the luminescence efficiency of LED, and gives the growth model of potential well material in GaN.According to the growth model, the growth temperature and the flow rate of the potential well layer were optimized, and the conclusion was drawn by the test and analysis of the experimental samples.The following are the main results obtained in this paper: for the effect of growth temperature of potential well layer material on material quality, the growth temperature rise sequence experiment is first carried out, and the materials and devices of the sample are tested.The results show that the dislocation density decreases and the photoluminescence intensity increases with the increase of growth temperature.The results also show that the change of temperature has little effect on in composition in quantum wells when the flow rate is low.By testing the electrical properties of the final device, it is found that increasing the growth temperature of the potential well material has a positive effect on the luminescence efficiency of LED, and the leakage caused by the dislocation of the device is also improved to a certain extent.Because of the low flow rate of in-doped in the temperature adjustment experiment, the experiment of raising in-doped flow rate is carried out in this paper.Through the test and analysis of the experimental samples, it can be seen that with the increase of the flow rate of in doped, the in component in quantum wells increases gradually.When the flow rate of in is increased a little, the growth quality of the material will be improved slightly, but when the flow rate of in is increased to a certain value, the dislocation density will increase greatly.At the same time, it is found that the photoluminescence intensity of quantum wells decreases when the flow rate of in doped is too large.By analyzing the energy band structure of quantum wells, it is found that increasing in doped flow increases the interlayer stress of well barrier, and the quantum Stark effect is more obvious.The final device test results show that increasing in-doped flow can increase the luminescence wavelength and luminescence efficiency.Although increasing in-doped flow can improve the luminous efficiency of the device, the luminous wavelength will also increase.Therefore, a third group of experiments have been carried out to solve this problem. At the same time, the devices with the same luminescence wavelength under different growth conditions are obtained by adjusting the growth temperature and the flow rate of in doped.The analysis of the device test results shows that the samples obtained by the growth temperature of 810 鈩，

本文编号：1755190