發(fā)布時(shí)間：2018-04-15 18:02

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

【摘要】：GaN基紫外LED由于其效率高、耗能少、堅(jiān)固耐用以及安全環(huán)保等優(yōu)勢(shì),在工業(yè)及日常生活中得到了廣泛應(yīng)用。但是,目前量子阱結(jié)構(gòu)的GaN基紫外LED發(fā)光效率仍然非常低,這嚴(yán)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(guó)內(nèi)外各機(jī)構(gòu)的研究熱點(diǎn)。本文的目的就是通過(guò)提升量子阱勢(shì)阱層材料生長(zhǎng)質(zhì)量來(lái)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(duì)提高LED發(fā)光效率的方法進(jìn)行了比較,并給出了勢(shì)阱層材料In GaN的生長(zhǎng)模型,根據(jù)生長(zhǎng)模型對(duì)勢(shì)阱層材料的生長(zhǎng)溫度和摻In流量進(jìn)行了優(yōu)化實(shí)驗(yàn),通過(guò)對(duì)實(shí)驗(yàn)樣品的測(cè)試與分析得出結(jié)論。以下是本文取得的主要成果:針對(duì)勢(shì)阱層材料生長(zhǎng)溫度對(duì)材料質(zhì)量的影響,本文首先進(jìn)行了生長(zhǎng)溫度升高序列實(shí)驗(yàn),并對(duì)樣品進(jìn)行了材料和器件的測(cè)試。測(cè)試結(jié)果表明,隨著生長(zhǎng)溫度的提高,材料中位錯(cuò)密度有所下降,量子阱光致發(fā)光強(qiáng)度隨之增大。測(cè)試結(jié)果還表明,在摻In流量較低時(shí),溫度較小幅度的改變對(duì)量子阱中In組分的影響不大。通過(guò)對(duì)最終器件的電學(xué)特性的測(cè)試發(fā)現(xiàn),提升勢(shì)阱層材料生長(zhǎng)溫度對(duì)LED發(fā)光效率產(chǎn)生了積極的影響,器件由于位錯(cuò)而導(dǎo)致的漏電現(xiàn)象也得到一定程度改善。由于溫度調(diào)整實(shí)驗(yàn)中摻In流量較小,所以本文針對(duì)性的進(jìn)行了提升摻In流量實(shí)驗(yàn)。通過(guò)對(duì)實(shí)驗(yàn)樣品的測(cè)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(shí),材料生長(zhǎng)質(zhì)量會(huì)有較小幅度改善,但是當(dāng)摻In流量增大到一定值時(shí),位錯(cuò)密度卻大幅度提升。同時(shí)發(fā)現(xiàn)摻In流量過(guò)大還會(huì)導(dǎo)致量子阱光致發(fā)光強(qiáng)度降低。通過(guò)對(duì)量子阱能帶結(jié)構(gòu)的分析發(fā)現(xiàn),提升摻In流量會(huì)增大阱壘層材料間應(yīng)力,量子斯塔克效應(yīng)會(huì)更加顯著。最終器件測(cè)試結(jié)果表明,提升摻In流量會(huì)使器件發(fā)光波長(zhǎng)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(zhǎng)也會(huì)增大。因此,針對(duì)這個(gè)問(wèn)題本文進(jìn)行了第三組實(shí)驗(yàn),同時(shí)調(diào)整生長(zhǎng)溫度和摻In流量,得到不同材料生長(zhǎng)條件下發(fā)光波長(zhǎng)相同的器件。對(duì)器件測(cè)試結(jié)果的分析表明,勢(shì)阱層材料生長(zhǎng)溫度為810℃,摻In流量為基礎(chǔ)流量的15%時(shí)得到的樣品有著較好的材料質(zhì)量和器件電特性。最終得到的器件在發(fā)光波長(zhǎng)為363.82nm時(shí),發(fā)光功率為43.33mW,比基礎(chǔ)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(guò)提升勢(shì)阱層材料生長(zhǎng)質(zhì)量來(lái)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(hào)：1755190