共查询到19条相似文献,搜索用时 93 毫秒
1.
对用LEO技术生长GaN材料的选择生长和横向生长速率进行了实验研究。结果表明,作为LEO生长基板的GaN层的表面质量是实现选择生长的关键,而图形方向对横向生长速率与纵向生长速率之比(L/V)也有重要的影响。通过选择合适的工艺条件,实现了GaN材料的LEO外延生长,所得样品的X射线衍射峰宽比用常规MOCVD法生长的样品减小了1/3。 相似文献
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用MOCVD法在LiGaO2(001)上生长GaN的研究 总被引:1,自引:0,他引:1
LiGaO2单晶是目前所知的GaN最为理想的衬底材料,本研究用金属有机物气相沉积法(MOCVD)在LiGaO2(001)衬底上进行了外延生长GaN膜的试验,生长出了表面较为平整的GaN外延膜。应用原子力显微镜(AFM)、X射线粉末衍射(XRD)和高分辨X射线双晶衍射分别对衬底对外延膜和衬底材料进行了分析测试。结果表明,用MOCVD法可以在LiGaO2(001)衬底上生长出较高质量的无掺杂GaN(0001)外延膜。但由于MOCVD法是在高温还原气氛中生长GaN外延膜的,LiGaO2在这种气氛中不够稳定,实验发现衬底材料在生长过程中部分样品发生开裂,但没有发生相变。 相似文献
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将以极化为特征、具有丰富功能特性的介电氧化物材料通过外延薄膜的方式,在半导体GaN上制备介电氧化物/GaN集成薄膜,其多功能一体化与界面耦合效应可推动电子系统单片集成化的进一步发展。然而,由于2类材料物理、化学性质的巨大差异,在GaN上生长介电薄膜会出现严重的相容性生长问题。采用激光分子束外延技术(LMBE),通过弹性应变的TiO2的缓冲层来减小晶格失配度,降低介电薄膜生长温度,控制界面应变释放而产生的失配位错,提高了介电薄膜外延质量;通过低温外延生长MgO阻挡层,形成稳定的氧化物/GaN界面,阻挡后续高温生长产生的扩散反应;最终采用TiO2/MgO组合缓冲层控制介电/GaN集成薄膜生长取向、界面扩散,降低集成薄膜的界面态密度,保护GaN半导体材料的性能。所建立的界面可控的相容性生长方法,为相关集成器件的研发提供了一条可行的新途径。 相似文献
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研究了不同衬底上MBE技术生长的InGaN的光学和结构特征。结果表明,在相同生长条件下,用图形化衬底生长的InGaN材料比用普通衬底生长的材料有较低的表面粗糙度和背景载流子浓度及较强的发光强度。通过透射电子显微镜(TEM)观察,发现普通衬底生长的InGaN内部原子错排现象严重,而采用图形化衬底生长的InGaN原子排列清晰规则。这主要是因为图形化衬底材料外延初期为横向生长模式,这种生长模式可有效地抑制穿透位错在GaN材料体系中的纵向延伸,降低GaN缓冲层中的位错密度,进而抑制外延InGaN材料中穿透位错和V型缺陷的产生。 相似文献
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宽带电子学器件具有效率高、温度和电流处理能力强等优点,非常适合于多种应用。例如,混合动力轿车和火车中将直流输出变换为交流信号以驱动马达,无线信号放大基站等。理想的器件应在同一材料衬底上制造以消除外延层中的应变,但大尺寸的GaN晶体很难制备,且晶体中位错密度很高。为此,日本大阪大学开发出一种溶液生长法生长GaN晶体, 相似文献
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自行设计了一套具有创新性的研究型立式高真空MOCVD装置,能够较好的调节反应气体的流动状态,从而在衬底上生长大面积均匀的外延层.利用该装置在蓝宝石和硅单晶衬底上成功地生长出高质量的GaN晶体薄膜.在蓝宝石衬底上生长出n、p型GaN以及多量子阱多层结构材料,并成功制备了GaN基多层量子阱结构的蓝光发光二极管,性能良好,具有实用价值. 相似文献
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LiGaO2单晶是目前所知的GaN最为理想的衬底材料,本研究用金属有机物气相沉积法(MOCVD)在LiGaO2(001)衬底上进行了外延生长GaN膜的试验,生长出了表面较为平整的GaN外延膜.应用原子力显微镜(AFM)、X射线粉末衍射(XRD)和高分辨X射线双晶衍射分别对衬底对外延膜和衬底材料进行了分析测试.结果表明,用MOCVD法可以在LiGaO2(001)衬底上生长出较高质量的无掺杂GaN(0001)外延膜.但由于MOCVD法是在高温还原气氛中生长GaN外延膜的,LiGaO2在这种气氛中不够稳定,实验发现衬底材料在生长过程中部分样品发生开裂,但没有发生相变. 相似文献
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A novel concept termed confined lateral guided growth (CLGG) has been demonstrated to prepare single crystalline GaN microtiles with a goal to create high crystalline quality and strain‐free GaN on large‐sized Si (111) substrates. Uniform array of hexagonal GaN tiles has been created with a diameter of larger than 30 μm for each tile. As revealed by the surface pits density of around 2 × 108 cm−2, the density of dislocations in these GaN tiles has been significantly reduced compared with that obtained typically from a GaN heteroepitaxy on Si (111). The strain in GaN tiles has been dramatically reduced to nearly zero. This approach offers a route to eliminate wafer‐bowing for growing high crystalline quality GaN on Si, especially when the substrate size scales to 12 in and beyond. The growth behavior and mechanism within these confined growth masks are investigated by both finite element modeling and experimental studying, indicating that CLGG is dominated by gas phase diffusion. 相似文献
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Nanoheteroepitaxial (NHE) growth of GaN using AlN/AlGaN as a graded buffer layer by metalorganic chemical vapor deposition has been demonstrated on the nanoporous patterned Si(111) substrates. The nanopore array on Si(111) has been fabricated by using anodized aluminum oxide membrane as an induced couple plasma dry etching mask. The reduction of the threading dislocation density and relaxation of the tensile stress in NHE GaN are revealed by transmission electron microscopy (TEM), micro-Raman spectrum and photoluminescence spectrum, respectively. Cross-sectional TEM analysis shows that dislocations nucleated at the interface are forced to bend into (0001) basal plane. Red shift in the E2 (TO) phonon peak of micro-Raman spectrum indicates the relaxation of tensile stress in the nanoheteroepitaxial lateral overgrowth of GaN. A single step ELO without mask on nanopatterned Si(111) substrates is a simple and promising way for the improvement of the quality of GaN on Si substrates. 相似文献
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The structural properties of GaN grown on AlGaN/AlN stress mitigating layers on 100-mm diameter Si (111) substrate by ammonia molecular beam epitaxy have been reported. High resolution X-ray diffraction, micro-Raman spectroscopy, transmission electron microscopy and secondary ion mass spectroscopy have been used to study the influence of AlN thickness and AlGaN growth temperature on the quality of GaN. GaN grown on thicker AlN showed reduced dislocation density and lesser tensile strain. Three-dimensional growth regime was observed for GaN grown at lower AlGaN growth temperature while higher AlGaN growth temperature resulted in two-dimensional growth mode. The dislocation bending and looping at the AlGaN/AlN interface was found to have significant influence on the dislocation density and strain in the GaN layer. The evolution and interaction of threading dislocations play a major role in determining the quality and the strain states of GaN. 相似文献
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Andrs Kovcs Martial Duchamp Rafal E. Dunin‐Borkowski Rositza Yakimova Pter L. Neumann Hannes Behmenburg Bartosz Foltynski Cristoph Giesen Michael Heuken Bla Pcz 《Advanced Materials Interfaces》2015,2(2)
The implementation of graphene layers in gallium nitride (GaN) heterostructure growth can solve self‐heating problems in nitride‐based high‐power electronic and light‐emitting optoelectronic devices. In the present study, high‐quality GaN layers are grown on patterned graphene layers and 6H–SiC by metalorganic chemical vapor deposition. A periodic pattern of graphene layers is fabricated on 6H–SiC by using polymethyl methacrylate deposition and electron beam lithography, followed by etching using an Ar/O2 gas atmosphere. Prior to GaN growth, an AlN buffer layer and an Al0.2Ga0.8N transition layer are deposited. The atomic structures of the interfaces between the 6H–SiC and graphene, as well as between the graphene and AlN, are studied using scanning transmission electron microscopy. Phase separation of the Al0.2Ga0.8N transition layer into an AlN and GaN superlattice is observed. Above the continuous graphene layers, polycrystalline defective GaN is rapidly overgrown by better quality single‐crystalline GaN from the etched regions. The lateral overgrowth of GaN results in the presence of a low density of dislocations (≈109 cm−2) and inversion domains and the formation of a smooth GaN surface. 相似文献
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The initial growth stage of self-induced GaN nanowires (NWs) on an AlN(0001)/Si(111) substrate is studied theoretically. Calculations are carried out within the model of Stranski-Krastanov quantum dot formation. The surface density of GaN islands is calculated, the formation of which precedes NW formation. GaN NW density is found as a function of gallium flux and deposition time for the case of molecular beam epitaxy growth. 相似文献
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Jing Wang L.W. Guo H.Q. Jia Z.G. Xing Y. Wang H. Chen J.M. Zhou 《Thin solid films》2006,515(4):1727-1730
A promising technique of lateral epitaxial overgrowth, namely CantiBridge epitaxy, is developed and demonstrated in order to reduce the threading dislocation density in GaN films. Using metalorganic chemical vapor deposition, the GaN films are grown on patterned sapphire fabricated by wet chemical etching, instead of traditional dry etching. The image of atomic force microscopy shows that the threading dislocations in CantiBridge-epitaxy GaN are reduced sharply, which makes a promising to realize the high-performance GaN-based optoelectronic devices. 相似文献
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J.Y. Moon H.Y. Kwon M.J. Shin Y.J. Choi H.S. Ahn J.H. Chang S.N. Yi Y.J. Yun D.H. Ha S.H. Park 《Materials Letters》2009,63(30):2695-2697
We grew one-dimensional GaN nanoneedles on AlN/Si(111) substrates at HCl/NH3 gas-flow ratios of 1/20, 1/30, and 1/50 using the hydride vapor-phase epitaxy (HVPE) method. Field emission-scanning electron microscopy (FE-SEM) images of GaN nanoneedles show that the vertical growth rate of GaN nanoneedles increases with increasing gas-flow ratio, but there is little growth in the lateral direction. X-ray diffraction patterns indicate that GaN nanoneedles grew with c-axes oriented perpendicular to the substrate. The room-temperature PL spectrum of GaN nanoneedles was detected at 3.237 eV of near-band-edge transitions. 相似文献
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High‐Brightness Blue Light‐Emitting Diodes Enabled by a Directly Grown Graphene Buffer Layer
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Zhaolong Chen Xiang Zhang Zhipeng Dou Tongbo Wei Zhiqiang Liu Yue Qi Haina Ci Yunyu Wang Yang Li Hongliang Chang Jianchang Yan Shenyuan Yang Yanfeng Zhang Junxi Wang Peng Gao Jinmin Li Zhongfan Liu 《Advanced materials (Deerfield Beach, Fla.)》2018,30(30)
Single‐crystalline GaN‐based light‐emitting diodes (LEDs) with high efficiency and long lifetime are the most promising solid‐state lighting source compared with conventional incandescent and fluorescent lamps. However, the lattice and thermal mismatch between GaN and sapphire substrate always induces high stress and high density of dislocations and thus degrades the performance of LEDs. Here, the growth of high‐quality GaN with low stress and a low density of dislocations on graphene (Gr) buffered sapphire substrate is reported for high‐brightness blue LEDs. Gr films are directly grown on sapphire substrate to avoid the tedious transfer process and GaN is grown by metal–organic chemical vapor deposition (MOCVD). The introduced Gr buffer layer greatly releases biaxial stress and reduces the density of dislocations in GaN film and InxGa1?xN/GaN multiple quantum well structures. The as‐fabricated LED devices therefore deliver much higher light output power compared to that on a bare sapphire substrate, which even outperforms the mature process derived counterpart. The GaN growth on Gr buffered sapphire only requires one‐step growth, which largely shortens the MOCVD growth time. This facile strategy may pave a new way for applications of Gr films and bring several disruptive technologies for epitaxial growth of GaN film and its applications in high‐brightness LEDs. 相似文献
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GaN nanowires (NWs) have been grown on Si(111) substrates by plasma-assisted molecular beam epitaxy (PAMBE). The nucleation process of GaN-NWs has been investigated in terms of nucleation density and wire evolution with time for a given set of growth parameters. The wire density increases rapidly with time and then saturates. The growth period until the nucleation of new nanowires is terminated can be defined as the nucleation stage. Coalescence of closely spaced nanowires reduces the density for long deposition times. The average size of the well-nucleated NWs shows linear time dependence in the nucleation stage. High-resolution transmission electron microscopy measurements of alternating GaN and AlN layers give valuable information about the length and radial growth rates for GaN and AlN in NWs. 相似文献