GaN納米材料的制備與表征
發(fā)布時(shí)間：2018-11-22 06:01
【摘要】：GaN材料與SiC、金剛石等半導(dǎo)體材料一起被稱為第三代半導(dǎo)體材料,GaN具有寬的禁帶寬度、高的擊穿電壓、高電子飽和速率及抗輻射能力,是發(fā)展高功率、高頻、高溫電子器件的理想材料,而且GaN發(fā)光效率較高,在制作藍(lán)綠光發(fā)光器件及半導(dǎo)體激光器等方面有著重要應(yīng)用。與體材料相比納米結(jié)構(gòu)具有以下優(yōu)點(diǎn),首先納米結(jié)構(gòu)中存在應(yīng)力弛豫會(huì)降低量子限制斯塔克效應(yīng),其次納米柱側(cè)壁為光子的釋放提供了更多的路徑,具有更高的出光效率。GaN納米結(jié)構(gòu)在固態(tài)照明領(lǐng)域的應(yīng)用亦成為近年來(lái)研究的熱點(diǎn)。關(guān)于GaN納米柱的制備有很多方法,包括VLS生長(zhǎng)法、光刻法以及納米壓印法等,本文采用自組織Ni納米島作為掩膜利用ICP刻蝕系統(tǒng)制備GaN納米柱,這種方法不同于以前在ICP刻蝕前需要用光刻技術(shù)來(lái)制備均勻周期性的納米模板,需要消耗高昂的費(fèi)用。用自組織的Ni納米顆粒作掩膜進(jìn)行納米結(jié)構(gòu)的制備,通常是在樣品上生長(zhǎng)一層Ni膜,然后在RTA中進(jìn)行快速熱退火,使其形成Ni納米島,以此作為后續(xù)制備納米結(jié)構(gòu)的掩膜。此外在實(shí)驗(yàn)過(guò)程中還可以通過(guò)控制最初生長(zhǎng)的Ni膜的厚度、快速退火的時(shí)間及溫度等參數(shù)來(lái)控制最終形成的Ni納米島的尺寸、密度以及占空比等分布情況,而且這種方法成本較低在大規(guī)模制備納米柱過(guò)程中可廣泛使用。本文即是采用這種方法在ICP系統(tǒng)中進(jìn)行GaN納米柱制備研究了不同刻蝕條件對(duì)納米柱刻蝕速率及發(fā)光性質(zhì)的影響,并用KOH對(duì)樣品進(jìn)行處理,所得結(jié)果如下：1.用自組織Ni納米島作為掩膜利用ICP刻蝕系統(tǒng)制備GaN納米柱,并研究了刻蝕過(guò)程不同刻蝕參數(shù)變化對(duì)納米柱刻蝕速率以及發(fā)光性質(zhì)的影響,隨著RF、ICP功率的升高,刻蝕速率也在不斷的增高,這分別與刻蝕過(guò)程中物理轟擊增強(qiáng)和反應(yīng)離子濃度的增加有關(guān),但發(fā)光強(qiáng)度并不隨RF、ICP的變化呈線性關(guān)系變化2.刻蝕之后納米柱的發(fā)光強(qiáng)度與薄膜相比明顯增強(qiáng),除此之外還發(fā)現(xiàn)刻蝕之后得到的GaN納米柱呈錐形結(jié)構(gòu),這是因?yàn)樵诩{米柱的刻蝕過(guò)程中存在橫向刻蝕,并非理想的垂直刻蝕,而且刻蝕后納米柱的尺寸比刻蝕模板要小一些,這是因?yàn)樵诳涛g過(guò)程中作為刻蝕掩膜的Ni納米顆粒也會(huì)被刻蝕。為了研究刻蝕前后應(yīng)力變化情況,分別測(cè)量了GaN薄膜和GaN納米柱的拉曼光譜,結(jié)果發(fā)現(xiàn)相對(duì)于GaN薄膜材料而言,GaN納米柱存在應(yīng)力釋放3.用KOH對(duì)樣品進(jìn)行處理,經(jīng)KOH處理的納米柱其發(fā)光強(qiáng)度較處理之前進(jìn)一步增強(qiáng),通過(guò)變溫PL譜的測(cè)量可知發(fā)光強(qiáng)度增強(qiáng)是由于內(nèi)量子效率的增強(qiáng)引起的,KOH腐蝕后內(nèi)量子效率的增加是因?yàn)樵诩{米柱刻蝕過(guò)程中會(huì)在樣品表面產(chǎn)生刻蝕損傷,這些刻蝕損傷作為非輻射復(fù)合中心會(huì)影響發(fā)光,而KOH腐蝕過(guò)程中會(huì)腐蝕掉這些損傷
[Abstract]:GaN materials, along with SiC, diamond and other semiconductor materials, are called the third generation semiconductor materials. GaN has wide band gap, high breakdown voltage, high electron saturation rate and radiation resistance, which is the development of high power and high frequency. GaN is an ideal material for high temperature electronic devices and has high luminescence efficiency. It has important applications in making blue-green photoluminescence devices and semiconductor lasers. Compared with bulk materials, nanostructures have the following advantages: firstly, the stress relaxation in nanostructures can reduce the quantum confinement Stark effect, and secondly, the lateral walls of the nanocolumns provide more paths for the release of photons. The application of GaN nanostructures in solid-state lighting has become a hot topic in recent years. There are many methods for the preparation of GaN nanorods, including VLS growth, lithography and nano-imprint. In this paper, self-organized Ni nanolayers are used as masks to fabricate GaN nanorods by ICP etching system. This method is different from that before ICP etching, which requires photolithography to fabricate uniform periodic nanotemplates, which requires high cost. The self-organized Ni nanoparticles are used as the mask for the preparation of nanostructures. Usually, a layer of Ni films is grown on the samples, and then annealed in RTA to form Ni nanoislands, which can be used as a mask for the subsequent preparation of nanostructures. In addition, the size, density and duty cycle distribution of the resulting Ni nanoliths can be controlled by controlling the thickness of the initial Ni films, the time and temperature of the rapid annealing, and so on. Moreover, this method can be widely used in the preparation of nano-columns at low cost. In this paper, the effects of different etching conditions on the etching rate and luminescence properties of GaN nanorods were studied by using this method in ICP system. The samples were treated with KOH. The results are as follows: 1. Self-organized Ni nanowires were used as masks to prepare GaN nanorods by ICP etching system. The effects of different etching parameters during etching on the etching rate and luminescence properties of nano-columns were studied. With the increase of RF,ICP power, the etching rate and luminescence properties of the nano-columns were studied. The etching rate is also increasing, which is related to the enhancement of physical bombardment and the increase of reaction ion concentration, but the luminescence intensity does not change linearly with the change of RF,ICP. After etching, the luminescence intensity of the nanocrystalline column is obviously higher than that of the thin film. In addition, it is also found that the GaN nanocolumn obtained by etching is conical, which is due to the existence of transverse etching in the etching process of the nanocrystalline column, which is not an ideal vertical etching. Moreover, the size of the nano-column is smaller than that of the etching template, because the Ni nanoparticles, which are used as the etching mask, are also etched during the etching process. In order to study the stress changes before and after etching, the Raman spectra of GaN film and GaN nanocolumn were measured, and the results showed that there was stress release in GaN nanocrystalline column compared with GaN film material. The luminescence intensity of the nano-column treated with KOH was further enhanced by KOH treatment. The measurement of PL spectrum at variable temperature showed that the enhancement of luminescence intensity was caused by the enhancement of internal quantum efficiency. The increase in quantum efficiency after KOH etching is due to the etching damage on the surface of the sample during the etching process of the nanoscale column, which acts as a non-radiative recombination center to affect the luminescence, while the KOH etching process corrodes the damage.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.1
本文編號(hào)：2348300
[Abstract]:GaN materials, along with SiC, diamond and other semiconductor materials, are called the third generation semiconductor materials. GaN has wide band gap, high breakdown voltage, high electron saturation rate and radiation resistance, which is the development of high power and high frequency. GaN is an ideal material for high temperature electronic devices and has high luminescence efficiency. It has important applications in making blue-green photoluminescence devices and semiconductor lasers. Compared with bulk materials, nanostructures have the following advantages: firstly, the stress relaxation in nanostructures can reduce the quantum confinement Stark effect, and secondly, the lateral walls of the nanocolumns provide more paths for the release of photons. The application of GaN nanostructures in solid-state lighting has become a hot topic in recent years. There are many methods for the preparation of GaN nanorods, including VLS growth, lithography and nano-imprint. In this paper, self-organized Ni nanolayers are used as masks to fabricate GaN nanorods by ICP etching system. This method is different from that before ICP etching, which requires photolithography to fabricate uniform periodic nanotemplates, which requires high cost. The self-organized Ni nanoparticles are used as the mask for the preparation of nanostructures. Usually, a layer of Ni films is grown on the samples, and then annealed in RTA to form Ni nanoislands, which can be used as a mask for the subsequent preparation of nanostructures. In addition, the size, density and duty cycle distribution of the resulting Ni nanoliths can be controlled by controlling the thickness of the initial Ni films, the time and temperature of the rapid annealing, and so on. Moreover, this method can be widely used in the preparation of nano-columns at low cost. In this paper, the effects of different etching conditions on the etching rate and luminescence properties of GaN nanorods were studied by using this method in ICP system. The samples were treated with KOH. The results are as follows: 1. Self-organized Ni nanowires were used as masks to prepare GaN nanorods by ICP etching system. The effects of different etching parameters during etching on the etching rate and luminescence properties of nano-columns were studied. With the increase of RF,ICP power, the etching rate and luminescence properties of the nano-columns were studied. The etching rate is also increasing, which is related to the enhancement of physical bombardment and the increase of reaction ion concentration, but the luminescence intensity does not change linearly with the change of RF,ICP. After etching, the luminescence intensity of the nanocrystalline column is obviously higher than that of the thin film. In addition, it is also found that the GaN nanocolumn obtained by etching is conical, which is due to the existence of transverse etching in the etching process of the nanocrystalline column, which is not an ideal vertical etching. Moreover, the size of the nano-column is smaller than that of the etching template, because the Ni nanoparticles, which are used as the etching mask, are also etched during the etching process. In order to study the stress changes before and after etching, the Raman spectra of GaN film and GaN nanocolumn were measured, and the results showed that there was stress release in GaN nanocrystalline column compared with GaN film material. The luminescence intensity of the nano-column treated with KOH was further enhanced by KOH treatment. The measurement of PL spectrum at variable temperature showed that the enhancement of luminescence intensity was caused by the enhancement of internal quantum efficiency. The increase in quantum efficiency after KOH etching is due to the etching damage on the surface of the sample during the etching process of the nanoscale column, which acts as a non-radiative recombination center to affect the luminescence, while the KOH etching process corrodes the damage.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.1
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