本文選題：非極性 + AlGaN材料　； 參考：《東南大學(xué)》2016年博士論文

【摘要】：AlGaN材料在室溫下的禁帶寬度范圍為3.4～6.2 eV,它可用于制備紫外發(fā)光器件和紫外探測(cè)器。紫外探測(cè)器具有重要的應(yīng)用價(jià)值,如保密通信、導(dǎo)彈預(yù)警、生化檢測(cè)、火焰監(jiān)測(cè)、電力設(shè)備監(jiān)測(cè)、紫外環(huán)境監(jiān)測(cè)、紫外光譜學(xué)和紫外天文學(xué)。就結(jié)構(gòu)而言,紫外探測(cè)器包括p-n結(jié)二極管、p-i-n結(jié)二極管、肖特基勢(shì)壘二極管和金屬-半導(dǎo)體-金屬(MSM)紫外探測(cè)器。由于MSM紫外探測(cè)器的制備工藝簡(jiǎn)單且可與場(chǎng)效應(yīng)晶體管技術(shù)兼容,因此這種探測(cè)器引起了人們的極大關(guān)注。非極性a面AlGaN材料在生長(zhǎng)方向上不存在極化電場(chǎng)且晶面內(nèi)具有光學(xué)偏振的各向異性,這提高了材料的輻射復(fù)合效率和光學(xué)偏振敏感度。因此,非極性a面AlGaN材料可用于制備紫外偏振敏感探測(cè)器(UV-PSPDs)。 UV-PSPDs可應(yīng)用于固態(tài)光源、光學(xué)存儲(chǔ)、生物光子學(xué)、偏振光探測(cè)和窄帶光探測(cè)等領(lǐng)域。本論文利用金屬有機(jī)化合物化學(xué)氣相外延(MOCVD)技術(shù)分別在極性c面和半極性r面藍(lán)寶石襯底上成功制備了極性c面AlGaN外延層、非極性a面GaN和AlGaN外延層。為了提高非極性a面GaN和AlGaN外延層的晶體質(zhì)量,本論文系統(tǒng)地優(yōu)化了外延層生長(zhǎng)的工藝參數(shù)。而且,本論文分別詳細(xì)地研究了Si摻雜和Mg摻雜對(duì)非極性a面GaN外延層、極性c面和非極性a面AlGaN外延層的結(jié)構(gòu)、電學(xué)和光學(xué)性質(zhì)的影響。本論文還分別定量地分析了極性c面AIN和AlGaN外延層的表面性質(zhì)。另外,本論文初步研究了MSM結(jié)構(gòu)的GaN基UV-PSPD。本論文的主要研究?jī)?nèi)容和取得的具體研究成果如下：1.分別利用低溫GaN和低溫AIN成核層在半極性(1102),面藍(lán)寶石襯底上生長(zhǎng)了非極性(1120)a面GaN外延層。采用優(yōu)化的Ⅴ/Ⅲ比、TMGa流量和反應(yīng)室壓力顯著地改善了非極性(1120)a面GaN外延層的表面形貌和晶體質(zhì)量。研究發(fā)現(xiàn),AlGaN插入層,特別是Al組分漸變的AlGaN插入層有助于改善非極性(1120)a面GaN外延層的表面形貌、晶體質(zhì)量和晶體結(jié)構(gòu)的各向異性。隨著SiH4流量的升高,Si雜質(zhì)的離化率將增大,導(dǎo)致Si摻雜非極性(1110)a面GaN外延層在室溫下的電子濃度增大。而較高的Si摻雜濃度有利于形成VGa這將增強(qiáng)Si摻雜非極性(1120)a面GaN外延層的黃帶發(fā)光。此外,Mg摻雜將引起非極性(1120)a面GaN外延層缺陷的增多,從而導(dǎo)致外延層的表面形貌劣化。雖然Mg摻雜幾乎不影響非極性(1120)a面GaN外延層沿c方向的晶體質(zhì)量,但將降低外延層沿m方向的晶體質(zhì)量,并增強(qiáng)外延層晶體結(jié)構(gòu)的各向異性。2.分別利用低溫AlN成核層和高溫AlN緩沖層技術(shù)在半極性(1102),面藍(lán)寶石襯底上生長(zhǎng)了非極性(1120)1面AlGaN外延層。對(duì)于非極性(1120)1面AlGaN外延層,提升高溫AIN緩沖層的Ⅴ/Ⅲ比和減小AlGaN緩沖層的厚度可有效地改善外延層的表面形貌。由于AlGaN插入層可有效地抑制生長(zhǎng)高溫AlN緩沖層時(shí)所產(chǎn)生的位錯(cuò)密度,因此AlGaN插入層,特別是Al組分漸變AlGaN插入層可明顯地改善非極性(1120)a而AlGaN外延層的晶體質(zhì)量和品體結(jié)構(gòu)的各向異性。然而研究也發(fā)現(xiàn),非極性(1120)a面AlGaN外延層的晶體質(zhì)量和表面形貌并不是正相關(guān)的。3.分別詳細(xì)地研究了Si摻雜對(duì)極性(0001)c面和非極性(1120)a面AlGaN外延層結(jié)構(gòu)、電學(xué)和光學(xué)性質(zhì)的影響。非極性(1120)a面AlGaN外延層比極性(0001)c面AlGaN外延層具有更強(qiáng)的結(jié)構(gòu)各向異性,因此Si摻雜更有利于釋放非極性(1120)a面AlGaN外延層的殘余壓應(yīng)力。Si摻雜有助于提高極性(0001)c面和非極性(1120)a面AlGaN外延層的晶體質(zhì)量,這是由于Si摻雜增加了材料中位錯(cuò)相互作用和消失的機(jī)會(huì)。由于隨著SiHH4流量從0增加到40 sccm, AlGaN材料中因Si摻雜產(chǎn)生的類受主增多,并補(bǔ)償了材料中的本征缺陷,因此極性(0001)c面和非極性(1120)α面AlGaN外延層的藍(lán)帶發(fā)光將增強(qiáng)。另外,插入A1N緩沖層和Al組分漸變AlGaN層將顯著地改善Mg摻雜極性(0001)c面AlGaN材料的表面形貌、晶體質(zhì)量和電學(xué)性質(zhì)。4.利用角度分辨X射線光電子能譜技術(shù)分別定量地研究了極性(0001)c面A1N和AlGaN外延層的表面性質(zhì)。暴露于空氣中的極性(0001)c面AlN和AlGaN外延層的表面被氧化為Al和Ga的氧化物,而且暴露于空氣中的具有較高Al組分的極性(0001)c面AlGaN外延層的表面存在更多的Al-O鍵,這是由于Al和0原子之間存在較大的化學(xué)親和勢(shì)。由于極性(0001)c面A1N外延層中的部分N原子被O原子取代,因此A1N外延層中存在N缺陷。隨著Al組分的增大,極性(0001)c面AlGaN外延層的Ga俄歇效應(yīng)被顯著地抑制。Al原子比Ga原子更容易被氧化且具有更低的表面遷移率,因此,較高Al組分的極性(0001)c面AlGaN外延層比對(duì)應(yīng)的低Al組分外延層的Al組分分布更不均勻。5.利用MOCVD技術(shù)在極性(0001)c面藍(lán)寶石襯底上生長(zhǎng)了極性(0001)c面Al0.28Ga0.72N/Al0.45Ga0.55N多量子阱,并對(duì)其結(jié)構(gòu)和光學(xué)性質(zhì)進(jìn)行了表征和分析。研究結(jié)果表明,極性(0001)c面Al0.28Ga0.72N/Al0.45Ga0.55N多量子阱在室溫的內(nèi)量子效率為18%。設(shè)計(jì)了AlInGaN多量子阱吸收區(qū)和倍增區(qū)分離的GaN基紫外探測(cè)器,這既可以提高探測(cè)器的量子效率和響應(yīng)度,并自由調(diào)諧其截止波長(zhǎng),又能有效地降低其擊穿電壓閾值。利用MOCVD技術(shù)在半極性(1102)r面藍(lán)寶石襯底上生長(zhǎng)的非極性(1120)a面GaN外延層的基礎(chǔ)上,制備了MSM結(jié)構(gòu)的GaN基UV-PSPD,并對(duì)探測(cè)器的性能進(jìn)行了表征和分析。研究結(jié)果表明,GaN基UV-PSPD在室溫且偏壓為10 V時(shí)光譜響應(yīng)的峰值為0.31 mA/W.此外,GaN基UV-PSPD的偏振敏感度的最大值Smax=1.5。
[Abstract]:The band gap of AlGaN materials is 3.4 ~ 6.2 eV at room temperature. It can be used to prepare UV light emitting devices and ultraviolet detectors. UV detectors have important application value, such as secure communication, missile early warning, biochemical detection, flame monitoring, electric power equipment monitoring, ultraviolet loop monitoring, ultraviolet spectroscopy and ultraviolet astronomy. The ultraviolet detector includes the p-n junction diode, the p-i-n junction diode, the Schottky barrier diode and the metal semiconductor metal (MSM) ultraviolet detector. Because the preparation process of the MSM UV detector is simple and can be compatible with the field effect transistor technology, the detector has aroused great concern. The non-polar a surface AlGaN material is in the birth. There is no polarization electric field and the anisotropy of optical polarization in the crystal surface, which improves the radiation recombination efficiency and optical polarization sensitivity of the material. Therefore, the nonpolar a AlGaN material can be used in the preparation of UV polarization sensitive detector (UV-PSPDs). UV-PSPDs can be applied to solid state light, optical storage, biophotonics, polarized light. In this paper, the polar C surface AlGaN epitaxial layer, non polar a surface GaN and AlGaN epitaxial layer have been successfully prepared on polar C and semi polar r surface sapphire substrates by chemical vapor phase epitaxy (MOCVD). This paper has been used to improve the crystal quality of non polar a surface GaN and AlGaN epitaxial layers. The technological parameters of epitaxial layer growth are systematically optimized. Furthermore, the effects of Si doping and Mg doping on the structure, electrical and optical properties of the non polar a surface GaN epitaxial layer, polar C surface and non polar a surface AlGaN epitaxial layer are investigated in this paper. The surface properties of AIN and AlGaN epitaxial layers of polar C surface are separately analyzed in this paper. In addition, the main research content and the specific research results of the GaN based UV-PSPD. paper of MSM structure are preliminarily studied as follows: 1. the non polar (1120) a surface epitaxial layer was grown on the semi polar (1102) and surface sapphire substrate by using low temperature GaN and low temperature AIN nucleation layer respectively. The optimized V / III ratio, TMGa flow and reaction were used. The chamber pressure significantly improved the surface morphology and crystal quality of the non polar (1120) a GaN epitaxial layer. It was found that the AlGaN insertion layer, especially the AlGaN insertion layer of the Al component, was helpful to improve the surface morphology, crystal mass and crystal structure anisotropy of the non polar (1120) a surface GaN epitaxial layer. With the increase of SiH4 flow, Si impurity The ionization rate will increase, which leads to the increase in the electron concentration of the Si doped non polar (1110) a surface GaN epitaxial layer at room temperature. The higher Si doping concentration is beneficial to the formation of VGa, which will enhance the yellow band luminescence of the Si doped non polar (1120) a surface GaN epitaxial layer. Moreover, Mg doping will lead to the increase of the GaN epitaxial layer defects of the non polar (1120) a surface, resulting in the extension of the epitaxial layer. The surface morphology of the layer is deteriorated. Although Mg doping does not affect the crystal mass of the non polar (1120) a surface GaN epitaxial layer along the c direction, it will reduce the crystal mass along the M direction in the epitaxial layer and enhance the anisotropic.2. of the epitaxial layer crystal structure by using the low-temperature AlN nucleation layer and the high temperature AlN buffer layer in the semi polar (1102), surface sapphire liner. The non polar (1120) 1 surface AlGaN epitaxial layer was grown on the bottom. For the non polar (1120) 1 surface AlGaN epitaxial layer, improving the V / III ratio of the high temperature AIN buffer layer and reducing the thickness of the AlGaN buffer layer can effectively improve the surface morphology of the epitaxial layer. As the AlGaN insertion layer can effectively inhibit the dislocation density produced by the growth of the high temperature AlN buffer layer, Al The GaN insertion layer, especially the Al component gradient AlGaN insertion layer, can obviously improve the crystal mass and the anisotropy of the crystalline structure of the non polar (1120) a and AlGaN epitaxial layer. However, it is also found that the crystal mass and surface morphology of the non polar (1120) a surface AlGaN epitaxial layer are not a positive correlation.3., respectively, to study the Si doping pair polarity respectively (0 001) C surface and non polar (1120) a surface AlGaN epitaxial layer structure, electrical and optical properties. Non polar (1120) a surface AlGaN epitaxial layer has stronger structural anisotropy than polarity (0001) C surface AlGaN epitaxial layer, so Si doping is more conducive to release the residual pressure stress.Si doping of non polar (1120) a surface AlGaN epitaxial layer helps to improve the polarity (000 1) the crystal quality of the C and non polar (1120) a surface AlGaN epitaxial layers, which is due to the chance that Si doping increases the dislocation interaction and disappearance of the material. As the SiHH4 flow increases from 0 to 40 SCCM, the Si doped class acceptor increases in the AlGaN material and compensates for the intrinsic defects in the material, therefore, the polarity (0001) C surface and non polarity (1120) the blue band luminescence of the AlGaN epitaxial layer of the alpha surface will be enhanced. In addition, the insertion of the A1N buffer layer and the Al component gradient AlGaN layer will significantly improve the surface morphology of the Mg doped polar (0001) C surface AlGaN material. The crystal quality and the electrical properties.4. use the angle resolved X ray photoelectron spectroscopy to quantitatively study the polarity (0001) C face A1N and AlGaN. The surface properties of the extended layer. The surfaces of the polar (0001) C surface AlN and AlGaN epitaxial layers exposed to air are oxidized to Al and Ga oxides, and there are more Al-O bonds on the surface of the polar (0001) C surface AlGaN epitaxial layer exposed to the higher Al components in the air, which is due to the larger chemical affinity between Al and 0 atoms. The partial N atom in the A1N epitaxial layer of polar (0001) C surface is replaced by O atoms, so there is a N defect in the A1N epitaxial layer. With the increase of the Al component, the Ga Auger effect of the AlGaN epitaxial layer on the polar (0001) C surface is significantly inhibited by the.Al atom is more easily oxidized and has a lower surface mobility than the Ga atom. Therefore, the polarity of the higher component is 0001 The Al component distribution of the surface AlGaN epitaxial layer is more uneven than that of the corresponding lower Al group..5. uses MOCVD technology to grow polar (0001) C surface Al0.28Ga0.72N/Al0.45Ga0.55N multiple quantum wells on the polar (0001) C surface sapphire substrate and characterizations and analysis of its structure and optical properties. The results show that polarity (0001) C face Al0.28Ga0 is shown. The internal quantum efficiency of.72N/Al0.45Ga0.55N multiple quantum wells at room temperature is 18%. designed for the AlInGaN multiple quantum well absorption area and the GaN based UV detector separated by the multiplier region. This can not only improve the quantum efficiency and response degree of the detector, but also freely tune its cut-off wavelength, and can effectively reduce the threshold of the breakdown voltage. MOCVD technology is used in the semi pole. On the basis of the non polar (1120) a surface GaN epitaxial layer on the R surface sapphire substrate, the GaN based UV-PSPD of the MSM structure is prepared and the performance of the detector is characterized and analyzed. The results show that the peak value of the GaN based UV-PSPD at room temperature and the partial pressure of 10 V time spectrum response is 0.31 mA/W. in addition, and the polarization sensitivity of GaN base UV-PSPD is sensitive. The maximum value of the degree Smax=1.5.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TN304;TN23

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本文編號(hào)：1953343