硅襯底GaN基LED光電性能及可靠性研究
發(fā)布時間:2018-05-25 06:57
本文選題:電子阻擋層 + 光功率。 參考:《南昌大學》2015年碩士論文
【摘要】:GaN基LED憑借其可控的全色光譜能隙以及優(yōu)良的物理化學性能,已逐步成為新一代綠色照明光源。為了獲得真正意義上的高品質(zhì)白光LED照明光源,需要采用全LED混光來實現(xiàn),需要采用紅、綠、藍三基色(RGB)的全LED混光來實現(xiàn),但是目前綠光的發(fā)光效率遠遠落后于藍光和紅光LED,學術(shù)界稱之為“Green gap”,這也成為實現(xiàn)RGB白光光源的主要技術(shù)瓶頸。因此,進一步提升綠光LED的光功率成為近幾年LED領(lǐng)域的研究熱點。基于硅襯底LED技術(shù)平臺,本文在保持p-GaN總體厚度不變的情況下通過改變靠近最后一個量子阱的電子阻擋層(EBL)AlGaN的厚度,較為系統(tǒng)地研究了電子阻擋層對硅襯底綠光LED的光功率(LOP)和工作電壓(VF2)的影響,另外經(jīng)過長時間對p-GaN中Mg摻雜濃度的跟蹤和外延薄膜表面形貌的觀察以及大量LED在老化過程中IR變化實驗進行了總結(jié)。主要獲得了以下研究成果:1、硅襯底GaN基綠光LED外延片薄膜在保持p層總體厚度不變的情況下對靠近最后一個量子阱的電子阻擋層(EBL)AlGaN厚度的進行了優(yōu)化及可靠性實驗,結(jié)果表明,p-AlGaN厚度為200?及P-InGaN厚度為400?的樣品D具有更高的光功率(LOP),且光電性能穩(wěn)定。并對其在大電流時光功率提高進行了解釋:大電流密度下隨著p-AlGaN的減薄使得該區(qū)域的電場增強,導(dǎo)致電子的有效勢壘高度增加和空穴有效勢壘高度減小。2、Mg摻雜濃度偏多會使芯片電壓偏高,因此需對P-GaN的摻Mg進行簡便有效地監(jiān)控。經(jīng)過長期測試發(fā)現(xiàn),p-GaN中Mg摻雜濃度偏高時在10μm*10μm的原子力顯微鏡(AFM)掃描范圍內(nèi)臺階流不明顯,而且會出現(xiàn)一些像小山丘一樣的凸起。并用二次離子質(zhì)譜儀(SIMS)對Mg元素進行了深度剖析,結(jié)果顯示有凸起出現(xiàn)的樣品中Mg的摻雜濃度確實偏高。因此提出用AFM方法快捷方便地監(jiān)控Mg的摻雜量。3、通過光電參數(shù)控制嚴格篩選出IR有差別的芯片,在大量老化實驗中發(fā)現(xiàn)IR小于0.05μA時篩選的芯片老化過程中相對穩(wěn)定,通過加載300V的靜電后可以篩選出高質(zhì)量的芯片,IR在0.05μA至0.1μA范圍內(nèi)的芯片老化過程中IR的穩(wěn)定性沒有前者高,而且只有加載1000V及以上的靜電后才能篩選出相對較好的芯片,IR在0.1μA至1μA內(nèi)的芯片老化效果較差,并且很難選出好的芯片。為篩選出的穩(wěn)定性好的芯片,建議點測時加相對小的靜電和分選時控制IR在較小的的范圍內(nèi)相結(jié)合的方法進行篩選。
[Abstract]:GaN based LED has gradually become a new generation of green light source with its controllable panchromatic spectral energy gap and excellent physical and chemical properties. In order to obtain the real high quality white light LED lighting source, all LED mixed light needs to be realized. The full LED mixed light of red, green and blue three basic colors (RGB) needs to be realized, but the green light is present at present. The luminescence efficiency is far behind the blue and red LED, which academic circles call "Green gap", which is also the main technical bottleneck for the realization of the RGB white light source. Therefore, to further improve the light power of the green light LED has become the research hotspot in the field of LED in recent years. Based on the flat platform of LED technology on the silicon substrate, this paper keeps the overall thickness of p-GaN unchanged. By changing the thickness of the electronic barrier layer (EBL) AlGaN near the last quantum well, the effects of the electronic barrier layer on the optical power (LOP) and the working voltage (VF2) of the green LED on silicon substrate are systematically investigated. In addition, the observation of the trace of the Mg doping concentration in p-GaN and the surface morphology of the epitaxial film in the p-GaN and a large number of LED in the old are also studied. The IR change experiments in the process are summarized. The main results are as follows: 1, the thickness of the electronic barrier layer (EBL) AlGaN near the last quantum well is optimized and dependable under the condition of keeping the overall thickness of the p layer unchanged. The results show that the thickness of the p-AlGaN is 200? And P-. The results show that the thickness of the p-AlGaN is 200? And P-. The sample D with a thickness of 400? With a thickness of 400? Has a higher optical power (LOP) and a stable optoelectronic performance. An explanation is made of the increase in the time power of the high current. With the decrease of the current density, the electric field of the region increases with the decrease of the p-AlGaN, resulting in the effective barrier height of the electrons and the decrease of the effective barrier height of the hole.2 and the Mg doping concentration. The voltage of the chip is much higher, so it is necessary to monitor and control the P-GaN doped Mg easily and effectively. After a long test, it is found that the Mg doping concentration in the p-GaN is not obvious in the 10 mu m*10 m atomic force microscope (AFM) scanning range, and there will be some bulges like the hills. And the two ion mass spectrometer (SIMS) is used for Mg. The depth analysis of the elements shows that the doping concentration of Mg in the samples with protruding is really high. Therefore, it is proposed that the doping amount of Mg can be monitored quickly and conveniently by AFM method, and the differential chip of IR is screened out strictly through the photoelectric parameter control. In a large number of aging experiments, the selected chip aging process is found when IR is less than 0.05 u A. Relatively stable, high quality chips can be screened by loading 300V static electricity. The stability of IR in the process of IR in the range of 0.05 to 0.1 A is not high, and only after loading 1000V and above, the relatively better chip can be screened. The aging effect of IR from 0.1 to 1 u A is poor, and it is very bad. It is difficult to select a good chip. In order to screen out the stable chip, it is suggested that the method of combination of relatively small static electricity and separation to control the combination of IR in a smaller range is proposed.
【學位授予單位】:南昌大學
【學位級別】:碩士
【學位授予年份】:2015
【分類號】:TQ133.51;TN312.8
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