本文選題：氮化鎵 + 發(fā)光二極管��； 參考：《西安電子科技大學》2015年碩士論文

【摘要】：GaN基紫外LED由于其效率高、耗能少、堅固耐用以及安全環(huán)保等優(yōu)勢,在工業(yè)及日常生活中得到了廣泛應用。但是,目前量子阱結構的GaN基紫外LED發(fā)光效率仍然非常低,這嚴重的限制了紫外LED的發(fā)展。所以,如何提高紫外LED的發(fā)光效率,尤其是其內(nèi)量子效率已經(jīng)成為國內(nèi)外各機構的研究熱點。本文的目的就是通過提升量子阱勢阱層材料生長質量來提高紫外LED器件的發(fā)光效率。本文介紹了LED器件的基本特性,對提高LED發(fā)光效率的方法進行了比較,并給出了勢阱層材料In GaN的生長模型,根據(jù)生長模型對勢阱層材料的生長溫度和摻In流量進行了優(yōu)化實驗,通過對實驗樣品的測試與分析得出結論。以下是本文取得的主要成果:針對勢阱層材料生長溫度對材料質量的影響,本文首先進行了生長溫度升高序列實驗,并對樣品進行了材料和器件的測試。測試結果表明,隨著生長溫度的提高,材料中位錯密度有所下降,量子阱光致發(fā)光強度隨之增大。測試結果還表明,在摻In流量較低時,溫度較小幅度的改變對量子阱中In組分的影響不大。通過對最終器件的電學特性的測試發(fā)現(xiàn),提升勢阱層材料生長溫度對LED發(fā)光效率產(chǎn)生了積極的影響,器件由于位錯而導致的漏電現(xiàn)象也得到一定程度改善。由于溫度調整實驗中摻In流量較小,所以本文針對性的進行了提升摻In流量實驗。通過對實驗樣品的測試與分析可知,隨著摻In流量的增大,量子阱中In組分逐漸增大。摻In流量少量增加時,材料生長質量會有較小幅度改善,但是當摻In流量增大到一定值時,位錯密度卻大幅度提升。同時發(fā)現(xiàn)摻In流量過大還會導致量子阱光致發(fā)光強度降低。通過對量子阱能帶結構的分析發(fā)現(xiàn),提升摻In流量會增大阱壘層材料間應力,量子斯塔克效應會更加顯著。最終器件測試結果表明,提升摻In流量會使器件發(fā)光波長增大,發(fā)光效率提高。雖然提升摻In流量能夠提升器件發(fā)光效率,但是發(fā)光波長也會增大。因此,針對這個問題本文進行了第三組實驗,同時調整生長溫度和摻In流量,得到不同材料生長條件下發(fā)光波長相同的器件。對器件測試結果的分析表明,勢阱層材料生長溫度為810℃,摻In流量為基礎流量的15%時得到的樣品有著較好的材料質量和器件電特性。最終得到的器件在發(fā)光波長為363.82nm時,發(fā)光功率為43.33mW,比基礎程序得到器件的發(fā)光效率提升了22.5%,這表明了本文通過提升勢阱層材料生長質量來提高紫外LED發(fā)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，

本文編號：1755190