本文選題：Si襯底 + 偏角　； 參考：《南昌大學》2015年碩士論文

【摘要】：Ga N基材料因其優(yōu)異的性能在固態(tài)照明方面具有廣泛的應(yīng)用前景。與Ga N常用的異質(zhì)外延襯底藍寶石和Si C相比,Si襯底具有價格低、導電導熱性能好、尺寸大、易于光電集成等優(yōu)點,在Si襯底上制備Ga N基LED的技術(shù)路線非常有發(fā)展?jié)摿?吸引了全球大量研究人員對其進行相關(guān)的研究。然而Ga N與Si襯底之間存在巨大的晶格失配和熱失配,這會在Ga N薄膜的外延生長引入巨大的失配應(yīng)力,進而會影響LED器件的性能。雖然近年來Si襯底Ga N基LED技術(shù)已取得了重大進展,其發(fā)光效率已逐步趕上藍寶石襯底LED,產(chǎn)業(yè)規(guī)模也在逐漸擴大,但與其獨特結(jié)構(gòu)相關(guān)的一些問題仍需要進一步研究。本文從Ga N薄膜外延生長和器件可靠性兩個方面著手進行了研究,一方面研究了Si襯底切偏角對Ga N基LED外延膜的影響,利用高分辨X射線衍射儀(HRXRD)、原子力顯微鏡(AFM)以及光致發(fā)光(PL)對外延薄膜的晶體質(zhì)量、量子阱中In組分、表面形貌及光學特性進行了研究。另一方面研究了垂直結(jié)構(gòu)芯片電老化過程中正向工作電壓VF2下降的問題,首先,研究了單純的熱效應(yīng)對器件老化過程中VF2變化的影響;然后,采用SIMS深度剖析技術(shù)分析了Si基LED芯片老化前后p-Ga N歐姆接觸界面Mg、Ga、N、Ag等元素的縱向分布情況以及p-Ga N中H元素濃度的變化情況;最后,對比了純Ag與Ni Ag Ni Ag兩種結(jié)構(gòu)器件的老化數(shù)據(jù),研究了Ni在LED老化過程中的影響�；谝陨蟽蓚�方面研究,本文取得了以下研究成果:1.Si(111)襯底偏角對量子阱中的In組分、Ga N外延膜的表面形貌、晶體質(zhì)量以及光學性能具有重大影響。為了獲得高質(zhì)量的Ga N外延薄膜,襯底偏角必須控制在小于0.5°范圍。超出此范圍,Ga N薄膜的晶體質(zhì)量、表面形貌及光學性能都明顯下降。2.開發(fā)出了一套滿足二次離子質(zhì)譜儀(SIMS)測試要求的Si基LED芯片試樣制備工藝,該工藝也可應(yīng)用于基于其它襯底制備的薄膜型LED芯片分析。3.老化過程所產(chǎn)生的熱效應(yīng)引起器件溫度上升是有限的,還不足以激活Mg受主,不會引起器件VF2下降;老化過程中p-Ga N歐姆接觸界面處的Mg、Ga、N、Ag元素均沒有發(fā)生縱向擴散,且p-Ga N中H元素濃度基本上也沒有發(fā)生變化,我們認為在老化過程中Mg-H絡(luò)合物發(fā)生分解后,當有載流子正向注入時H+俘獲電子變成H0,而H0是一種穩(wěn)定狀態(tài)不會鈍化Mg。老化電壓的下降是由于Mg受主在電注入的作用下被進一步激活,使受主濃度增加,引起p型層電導率上升,器件的VF2下降。4.純Ag結(jié)構(gòu)器件在老化過程中電壓會下降0.2V左右,而N i Ag N i Ag結(jié)構(gòu)的器件在老化過程中電壓幾乎不會下降。p型歐姆接觸層采用Ni有利于提高Si基LED器件的穩(wěn)定性。
[Abstract]:Gan-based materials have been widely used in solid-state lighting due to their excellent properties. Compared with gan heteroepitaxial sapphire and sic substrate, Si substrate has the advantages of low price, good thermal conductivity, large size and easy photoelectric integration. It has attracted a large number of researchers around the world to do related research. However, there is a huge lattice mismatch and thermal mismatch between gan and Si substrates, which will introduce a huge mismatch stress into the epitaxial growth of gan thin films, which will affect the performance of LED devices. In recent years, Ga N-based LED technology on Si substrate has made great progress, its luminescence efficiency has gradually caught up with the LED substrate of sapphire substrate, and the industrial scale is gradually expanding, but some problems related to its unique structure still need to be further studied. In this paper, the epitaxial growth and device reliability of gan thin films are studied. On the one hand, the influence of the cut angle of Si substrates on gan based LED epitaxial films is studied. The crystal quality, in composition, surface morphology and optical properties of epitaxial thin films were investigated by high resolution X-ray diffractometer (HRXRD), atomic force microscopy (AFM) and photoluminescence (PL). On the other hand, the problem of the decrease of the forward working voltage VF2 during the electric aging of the vertical chip is studied. Firstly, the effect of the pure thermal effect on the VF2 changes during the aging process of the device is studied. The longitudinal distribution of p-Ga N ohmic contact interface and the change of H concentration in p-Ga N were analyzed by Sims depth analysis technique before and after aging. The aging data of pure Ag and Ni Ag Ni Ag structures were compared, and the effect of Ni on the aging process of LED was studied. Based on the above two aspects, the following results have been obtained: 1. The substrate deflection angle has great influence on the surface morphology, crystal quality and optical properties of in composition gan epitaxial films in quantum wells. In order to obtain high quality gan epitaxial films, the substrate deflection angle must be controlled in the range of less than 0.5 擄. Beyond this range, the crystal quality, surface morphology and optical properties of gan thin films decreased significantly. A sample preparation process for Si-based LED chips which meets the requirements of secondary ion mass spectrometer (SIMS) testing has been developed. The process can also be applied to the analysis of thin film LED chips based on other substrates. The temperature rise caused by the thermal effect during aging is limited, which is not enough to activate mg acceptor and not cause VF2 decrease, and there is no longitudinal diffusion at the contact interface of p-Ga N ohmic contact. The concentration of H in p-Ga N has not changed. It is considered that after the decomposition of Mg-H complex during aging, the H trapping electron becomes H0 when there is positive carrier injection, and H0 is a stable state that does not passivate mg. The decrease of aging voltage is due to the further activation of mg acceptor under the action of electric injection, which leads to the increase of acceptor concentration and the increase of the conductivity of p-type layer, and the decrease of VF2 of the device by .4. The voltage of pure Ag structure device will decrease about 0.2 V during aging, while the voltage of Ni Ag structure device will hardly decrease during aging process. The use of Ni type ohmic contact layer can improve the stability of Si based LED device.
【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】：TN312.8

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本文編號：2006835