本文關(guān)鍵詞：微納結(jié)構(gòu)增強(qiáng)GaN基LED發(fā)光效率的研究　出處：《江南大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 微納結(jié)構(gòu) GaN基LED 表面等離激元 時域有限差分法 ICP刻蝕

【摘要】：隨著GaN基發(fā)光二極管(LEDs)的快速發(fā)展,LED以其優(yōu)越的性能正逐漸替代傳統(tǒng)照明器件被廣泛應(yīng)用在各個領(lǐng)域,它不僅具備發(fā)光效率高、響應(yīng)時間短、光譜可調(diào)范圍大、壽命長等優(yōu)點(diǎn),同時還具有材料無污染、節(jié)能等諸多優(yōu)點(diǎn)。盡管LED的商業(yè)應(yīng)用已經(jīng)比較普遍,價格也比較低廉,但其仍面臨需要克服外量子效率低的問題,關(guān)鍵在于如何解決由于GaN材料和外界空氣界面處全反射角所引起的光提取率低問題。目前常用的方法有光子晶體、倒裝芯片、透明襯底、表面粗化、等離激元等技術(shù)。本文主要是通過在半導(dǎo)體表面制備微納結(jié)構(gòu)增強(qiáng)GaN基LED的發(fā)光效率,主要分為沉積金屬薄膜、金屬顆粒和刻蝕三個部分,并對幾種微納結(jié)構(gòu)下的LED光致發(fā)光譜進(jìn)行對比分析。具體研究工作和相關(guān)結(jié)果如下:1.利用時域差分有限元的方法(FDTD)研究了金屬納米粒子增強(qiáng)GaN紫外LED的光提取率。結(jié)構(gòu)包含不同尺寸、間距的Al納米粒子,同時還包括非對稱結(jié)構(gòu)的Al納米粒子。通過調(diào)節(jié)納米粒子的尺寸和間距可以改變光譜的響應(yīng)范圍,發(fā)現(xiàn)電場增強(qiáng)分布和峰值的位置也和納米粒子的結(jié)構(gòu)對稱性有關(guān)。通過調(diào)節(jié)非對稱結(jié)構(gòu)的納米粒子參數(shù)可以獲得較大增強(qiáng)比例,為獲得高效的深紫外LED提供參考價值。2.利用磁控濺射鍍膜儀設(shè)備在GaN基LED外延片表面沉積不同厚度的金屬Ag薄膜,采用光致發(fā)光譜來表征外延片的發(fā)光效率,得出了三種不同厚度的金屬薄膜對其發(fā)光效率的影響,FDTD仿真結(jié)果驗證了在金屬表面出現(xiàn)場增強(qiáng)的效果。3.通過對金屬薄膜進(jìn)行退火處理得到金屬納米粒子,實驗研究了三種不同直徑的金屬Ag納米粒子對GaN基LED發(fā)光效率的影響,同時使用FDTD軟件從理論上計算了三種直徑Ag納米顆粒的消光光譜,計算結(jié)果和實驗結(jié)果能夠較好的吻合。同時電場增強(qiáng)在Ag納米顆粒周圍的效果更加明顯,與預(yù)期一致。其PL光譜的增強(qiáng)比例最大提升219%。4.采用電感耦合等離子體技術(shù)(ICP)對GaN基LED的P型層進(jìn)行刻蝕,經(jīng)過ICP刻蝕后的LED器件發(fā)光效率明顯增強(qiáng),接著在刻蝕后的納米線結(jié)構(gòu)上沉積金屬顆粒,并將實驗結(jié)果與前面兩種實驗方式進(jìn)行對比。對量子阱進(jìn)行PL測試發(fā)現(xiàn),對比原位外延片其PL光譜在峰值處增加了224%,是鍍銀納米顆粒樣片的1.2倍,表明在Ag納米顆粒和納米線直接有很強(qiáng)的表面等離激元耦合和散射作用。
[Abstract]:With the rapid development of LEDs, LEDs have been widely used in various fields because of their superior performance. They not only have high luminous efficiency. LED has many advantages, such as short response time, wide spectrum adjustable range, long life, no pollution of materials, energy saving and so on. Although the commercial application of LED is already relatively common, the price is also relatively low. However, it is still faced with the need to overcome the problem of low external quantum efficiency. The key lies in how to solve the problem of low optical extraction rate caused by the total reflection angle between GaN material and external air interface. At present, the commonly used methods are photonic crystal, flip chip, transparent substrate, and surface coarsening. In this paper, the luminescence efficiency of GaN based LED is enhanced by fabricating micro and nano structure on semiconductor surface, which is mainly divided into three parts: deposition metal film, metal particle and etching. The LED photoluminescence spectra of several micro and nano structures are compared and analyzed. The specific research work and related results are as follows: 1. Using the finite element method of time-domain difference (FDTD). The optical extraction rate and structure of metal nanoparticles enhanced GaN UV LED were studied. The response range of the spectrum can be changed by adjusting the size and spacing of the nano-particles. It is found that the distribution of electric field enhancement and the position of peak value are also related to the structure symmetry of the nanoparticles, and a large proportion of the nanoparticles can be obtained by adjusting the parameters of the asymmetric structure. In order to obtain highly efficient deep ultraviolet (LED), reference value is provided. 2. Using magnetron sputtering equipment, Ag thin films of different thickness are deposited on the surface of GaN based LED epitaxial wafers. Photoluminescence spectra were used to characterize the luminescence efficiency of the epitaxial wafers, and the effects of three kinds of metal films with different thickness on the luminescence efficiency were obtained. FDTD simulation results verify the effect of in-situ enhancement on the metal surface. 3. The metal nanoparticles are obtained by annealing the metal film. The effects of three kinds of metal Ag nanoparticles with different diameters on the luminescence efficiency of GaN based LED were studied experimentally. The extinction spectra of three Ag nanoparticles with different diameters were calculated theoretically by using FDTD software. The calculated results are in good agreement with the experimental results, and the effect of electric field enhancement around Ag nanoparticles is more obvious. The enhancement ratio of PL spectrum is maximum 219.4.The P-type layer of GaN based LED is etched by inductively coupled plasma technique. The luminescence efficiency of LED device after ICP etching is obviously enhanced, and then the metal particles are deposited on the nanowire structure after etching. The PL spectra of the quantum wells are increased by 224% at the peak compared with the in situ epitaxial wafers. The results show that Ag nanoparticles and nanowires have strong surface coupling and scattering.
【學(xué)位授予單位】：江南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN312.8

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