非极性AlGaN材料生长及探测器制备技术研究

发布时间：2018-05-30 01:36

  本文选题：非极性 + AlGaN材料　； 参考：《东南大学》2016年博士论文

【摘要】：AlGaN材料在室温下的禁带宽度范围为3.4～6.2 eV,它可用于制备紫外发光器件和紫外探测器。紫外探测器具有重要的应用价值,如保密通信、导弹预警、生化检测、火焰监测、电力设备监测、紫外环境监测、紫外光谱学和紫外天文学。就结构而言,紫外探测器包括p-n结二极管、p-i-n结二极管、肖特基势垒二极管和金属-半导体-金属(MSM)紫外探测器。由于MSM紫外探测器的制备工艺简单且可与场效应晶体管技术兼容,因此这种探测器引起了人们的极大关注。非极性a面AlGaN材料在生长方向上不存在极化电场且晶面内具有光学偏振的各向异性,这提高了材料的辐射复合效率和光学偏振敏感度。因此,非极性a面AlGaN材料可用于制备紫外偏振敏感探测器(UV-PSPDs)。 UV-PSPDs可应用于固态光源、光学存储、生物光子学、偏振光探测和窄带光探测等领域。本论文利用金属有机化合物化学气相外延(MOCVD)技术分别在极性c面和半极性r面蓝宝石衬底上成功制备了极性c面AlGaN外延层、非极性a面GaN和AlGaN外延层。为了提高非极性a面GaN和AlGaN外延层的晶体质量,本论文系统地优化了外延层生长的工艺参数。而且,本论文分别详细地研究了Si掺杂和Mg掺杂对非极性a面GaN外延层、极性c面和非极性a面AlGaN外延层的结构、电学和光学性质的影响。本论文还分别定量地分析了极性c面AIN和AlGaN外延层的表面性质。另外,本论文初步研究了MSM结构的GaN基UV-PSPD。本论文的主要研究内容和取得的具体研究成果如下：1.分别利用低温GaN和低温AIN成核层在半极性(1102),面蓝宝石衬底上生长了非极性(1120)a面GaN外延层。采用优化的Ⅴ/Ⅲ比、TMGa流量和反应室压力显著地改善了非极性(1120)a面GaN外延层的表面形貌和晶体质量。研究发现,AlGaN插入层,特别是Al组分渐变的AlGaN插入层有助于改善非极性(1120)a面GaN外延层的表面形貌、晶体质量和晶体结构的各向异性。随着SiH4流量的升高,Si杂质的离化率将增大,导致Si掺杂非极性(1110)a面GaN外延层在室温下的电子浓度增大。而较高的Si掺杂浓度有利于形成VGa这将增强Si掺杂非极性(1120)a面GaN外延层的黄带发光。此外,Mg掺杂将引起非极性(1120)a面GaN外延层缺陷的增多,从而导致外延层的表面形貌劣化。虽然Mg掺杂几乎不影响非极性(1120)a面GaN外延层沿c方向的晶体质量,但将降低外延层沿m方向的晶体质量,并增强外延层晶体结构的各向异性。2.分别利用低温AlN成核层和高温AlN缓冲层技术在半极性(1102),面蓝宝石衬底上生长了非极性(1120)1面AlGaN外延层。对于非极性(1120)1面AlGaN外延层,提升高温AIN缓冲层的Ⅴ/Ⅲ比和减小AlGaN缓冲层的厚度可有效地改善外延层的表面形貌。由于AlGaN插入层可有效地抑制生长高温AlN缓冲层时所产生的位错密度,因此AlGaN插入层,特别是Al组分渐变AlGaN插入层可明显地改善非极性(1120)a而AlGaN外延层的晶体质量和品体结构的各向异性。然而研究也发现,非极性(1120)a面AlGaN外延层的晶体质量和表面形貌并不是正相关的。3.分别详细地研究了Si掺杂对极性(0001)c面和非极性(1120)a面AlGaN外延层结构、电学和光学性质的影响。非极性(1120)a面AlGaN外延层比极性(0001)c面AlGaN外延层具有更强的结构各向异性,因此Si掺杂更有利于释放非极性(1120)a面AlGaN外延层的残余压应力。Si掺杂有助于提高极性(0001)c面和非极性(1120)a面AlGaN外延层的晶体质量,这是由于Si掺杂增加了材料中位错相互作用和消失的机会。由于随着SiHH4流量从0增加到40 sccm, AlGaN材料中因Si掺杂产生的类受主增多,并补偿了材料中的本征缺陷,因此极性(0001)c面和非极性(1120)α面AlGaN外延层的蓝带发光将增强。另外,插入A1N缓冲层和Al组分渐变AlGaN层将显著地改善Mg掺杂极性(0001)c面AlGaN材料的表面形貌、晶体质量和电学性质。4.利用角度分辨X射线光电子能谱技术分别定量地研究了极性(0001)c面A1N和AlGaN外延层的表面性质。暴露于空气中的极性(0001)c面AlN和AlGaN外延层的表面被氧化为Al和Ga的氧化物,而且暴露于空气中的具有较高Al组分的极性(0001)c面AlGaN外延层的表面存在更多的Al-O键,这是由于Al和0原子之间存在较大的化学亲和势。由于极性(0001)c面A1N外延层中的部分N原子被O原子取代,因此A1N外延层中存在N缺陷。随着Al组分的增大,极性(0001)c面AlGaN外延层的Ga俄歇效应被显著地抑制。Al原子比Ga原子更容易被氧化且具有更低的表面迁移率,因此,较高Al组分的极性(0001)c面AlGaN外延层比对应的低Al组分外延层的Al组分分布更不均匀。5.利用MOCVD技术在极性(0001)c面蓝宝石衬底上生长了极性(0001)c面Al0.28Ga0.72N/Al0.45Ga0.55N多量子阱,并对其结构和光学性质进行了表征和分析。研究结果表明,极性(0001)c面Al0.28Ga0.72N/Al0.45Ga0.55N多量子阱在室温的内量子效率为18%。设计了AlInGaN多量子阱吸收区和倍增区分离的GaN基紫外探测器,这既可以提高探测器的量子效率和响应度,并自由调谐其截止波长,又能有效地降低其击穿电压阈值。利用MOCVD技术在半极性(1102)r面蓝宝石衬底上生长的非极性(1120)a面GaN外延层的基础上,制备了MSM结构的GaN基UV-PSPD,并对探测器的性能进行了表征和分析。研究结果表明,GaN基UV-PSPD在室温且偏压为10 V时光谱响应的峰值为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.
【学位授予单位】：东南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN304;TN23

【相似文献】

相关期刊论文 前10条

1 赵建芝;林兆军;Corrigan T D;张宇;李惠军;王占国;;Influence of annealed ohmic contact metals on electron mobility of strained AlGaN/GaN heterostructures[J];半导体学报;2009年10期

2 孙再吉;;开发插入AlGaN层的InAlN/AlGaN/GaN FETs[J];半导体信息;2010年04期

3 任凡;郝智彪;王磊;汪莱;李洪涛;罗毅;;Effects of SiN_x on two-dimensional electron gas and current collapse of AlGaN/GaN high electron mobility transistors[J];Chinese Physics B;2010年01期

4 纪攀峰;刘乃鑫;魏同波;刘U，

本文编号：1953343