Si基氨化ZnO/Ga2O3薄膜制备GaN纳米线

利用射频磁控溅射法在Si(111)衬底上溅射ZnO中间层和Ga2O3薄膜,然后在管式炉中常压下通氨气对ZnO/Ga2O3薄膜进行氨化,高温下ZnO层在氨气气氛中挥发,而Ga2O3薄膜和氨气反应合成出GaN纳米线.X射线衍射测量结果表明利用该方法制备的GaN纳米线具有沿c轴方向择优生长的六角纤锌矿结构.利用扫描电子显微镜、透射电子显微镜、傅里叶红外透射谱、能量弥散谱及选区电子衍射观测并分析了样品的形貌、成分和晶格结构.研究发现ZnO层的挥发有利于Ga2O3和NH3反应合成GaN纳米线.     

Si基氨化ZnO／Ga2O3薄膜制备GaN纳米线

利用射频磁控溅射法在Si(111)衬底上溅射ZnO中间层和Ga2O3薄膜，然后在管式炉中常压下通氨气对ZnO/Ga2O3薄膜进行氨化，高温下ZnO层在氨气气氛中挥发，而Ga2O3薄膜和氨气反应合成出GaN纳米线．X射线衍射测量结果表明利用该方法制备的GaN纳米线具有沿c轴方向择优生长的六角纤锌矿结构．利用扫描电子显微镜、透射电子显微镜、傅里叶红外透射谱、能量弥散谱及选区电子衍射观测并分析了样品的形貌、成分和晶格结构．研究发现ZnO层的挥发有利于Ga2O3和NH3反应合成GaN纳米线．     

RF磁控溅射和氨化法制备GaN纳米棒和纳米颗粒

利用射频磁控溅射法分别溅射ZnO中间层和Ga2O3薄膜到Si(111)衬底上,然后ZnO/Ga2O3薄膜在管式石英炉中常压下通氨气进行氨化,高温下ZnO在氨气气氛中被还原生成Zn而升华,而在不同的氨化时间下Ga2O3和氨气反应合成出GaN纳米棒和纳米颗粒。X射线衍射(XRD)测量结果表明,利用该方法制备GaN纳米棒和颗粒具有沿c轴择优取向生长的六方纤锌矿结构。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶红外透射谱(FTIR)及选区电子衍射(SAED)观测和分析了样品的形貌、成分和晶格结构。研究分析了此种方法合成GaN纳米结构的反应机制。     

氨化法制备大量单晶GaN纳米线及其特性研究

利用磁控溅射技术先在硅村底上制备Ga2O3/Co薄膜,然后在管式炉中通入流动的氨气在950℃对薄膜进行氨化,反应后成功制备出大量GaN纳米线.采用X射线衍射(xRD)、傅里叶红外吸收光谱(FTIR)、扫描电子显微镜(SEM)和高分辨透射电子显微镜(HRTEM)对样品进行分析.结果表明,采用此方法得到了六方纤锌矿结构的GaN单晶纳米线,纳米线的直径在50 nm～150 nm范围内,长度为几十微米.     

氨化Si基Ga2O3/Co薄膜合成GaN纳米线及其表征

采用磁控溅射技术先在Si衬底上制备Ga2O3/Co薄膜,然后在950"C下流动的氨气中进行氨化反应制备GaN纳米棒.应用X射线衍射、扫描电镜、傅里叶红外吸收光谱、选区电子衍射和高分辨透射电子显微镜对样品进行表征.结果表明,采用此方法得到了六方纤锌矿结构的GaN单晶纳米棒.观察发现纳米棒表面光滑.并讨论了GaN纳米棒的生长机制.     

氨化Si基Ga2O3/Co薄膜合成GaN纳米线及其表征

采用磁控溅射技术先在Si衬底上制备Ga2O3/Co薄膜,然后在950"C下流动的氨气中进行氨化反应制备GaN纳米棒.应用X射线衍射、扫描电镜、傅里叶红外吸收光谱、选区电子衍射和高分辨透射电子显微镜对样品进行表征.结果表明,采用此方法得到了六方纤锌矿结构的GaN单晶纳米棒.观察发现纳米棒表面光滑.并讨论了GaN纳米棒的生长机制.     

氨化Ga_2O_3/Mg薄膜制备簇状GaN纳米线

通过在1050°C时氨化Ga2O3/Mg薄膜制备出簇状GaN纳米线。用X射线衍射(XRD),傅里叶红外吸收光谱(FTIR)扫描电子显微镜(SEM)和高分辨电子显微镜(HRTEM)对样品进行测试分析。结果表明,GaN纳米线为六万纤锌矿结构单晶相并且成族生长,直径在200～500nm米左右,其长度可达5～10μm。几乎所有纳米线的直径均有逐渐缩小的趋势。对Mg膜的作用进行了初步的分析。     

RF磁控溅射和氮化法制备GaN纳米棒和纳米颗粒

利用射频磁控溅射法分别溅射ZnO中间层和Ga2O3薄膜到Si（111）衬底上，然后ZnO／Ga2O3薄膜在管式石英炉中常压下通氨气进行氨化，高温下ZnO在氨气气氛中被还原生成Zn而升华，而在不同的氨化时间下Ga2O3和氨气反应合成出GaN纳米棒和纳米颗粒。X射线衍射（XRD）测量结果表明，利用该方法制备GaN纳米棒和颗粒具有沿c轴择优取向生长的六方纤锌矿结构。利用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、傅里叶红外透射谱（FTIR）及选区电子衍射（SAED）观测和分析了样品的形貌、成分和晶格结构。研究分析了此种方法合成GaN纳米结构的反应机制。     

磁控溅射和氨化法生长GaN纳米棒及其特性

使用一种新奇的稀土元素铽(Tb)作催化剂,通过氨化磁控溅射在Si(111)衬底上的Ga2O3/Tb薄膜,合成了大量的GaN纳米棒,氨化温度为950℃,氨化时间为15min。该方法可以进行持续合成且制备的GaN纳米棒纯度较高、成本低廉。实验后分别用扫描电子显微镜(SEM)、X射线衍射(XRD)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)和X射线光电子能谱(XPS)对样品进行了结构、表面形态和成分测试。通过XRD和XPS测试分析,合成的纳米棒具有六方纤锌矿GaN结构;通过SEM、TEM和HRTEM观察分析得出合成的纳米棒为单晶GaN纳米棒。简单讨论了GaN纳米棒的生长机制。     

石墨烯上生长GaN纳米线

采用金属Ga升华法在石墨烯/蓝宝石衬底上生长了高质量GaN纳米线,研究了不同的生长条件,如NH3流量、反应时间、催化剂和缓冲层等对GaN纳米线形貌的影响,采用扫描电子显微镜(SEM)对GaN纳米线进行表征.研究发现,在适当的NH3流量且无催化剂时,衬底上可以生长出粗细均匀的GaN纳米线.反应时间为5 min时,纳米线密集分布在衬底上,表面光滑.在石墨烯/蓝宝石上预先低温生长GaN缓冲层,然后升温至1 100℃进行GaN纳米线生长,获得了具有择优取向的GaN纳米线结构.研究表明,石墨烯和缓冲层对获得GaN纳米线结构有序阵列具有重要的作用.     

Remote plasma-enhanced atomic layer deposition of gallium oxide thin films with NH_3 plasma pretreatment

High quality gallium oxide(Ga_2O_3) thin films are deposited by remote plasma-enhanced atomic layer deposition(RPEALD) with trimethylgallium(TMG) and oxygen plasma as precursors. By introducing in-situ NH3 plasma pretreatment on the substrates, the deposition rate of Ga_2O_3 films on Si and GaN are remarkably enhanced, reached to 0.53 and 0.46 ?/cycle at 250 °C,respectively. The increasing of deposition rate is attributed to more hydroxyls(–OH) generated on the substrate surfaces after NH3 pretreatment, which has no effect on the stoichiometry and surface morphology of the oxide films, but only modifies the surface states of substrates by enhancing reactive site density. Ga_2O_3 film deposited on GaN wafer is crystallized at 250 °C, with an epitaxial interface between Ga_2O_3 and GaN clearly observed. This is potentially very important for reducing the interface state density through high quality passivation.     

Synthesis of GaN nanowires and nanorods via self-growth mode control

The synthesis of hexagonal wurzite one-dimensional (1D) GaN nanostructures on c-Al₂O₃ substrates was investigated using a thermal chemical vapor deposition (CVD) process. The diameter of the GaN nanostructures was controlled by varying the growth time using a mixture of GaN powder and Ga metal with the ammonia gas reaction. The morphologies of the GaN nanowires and nanorods were confirmed by field emission scanning electron microscopy. The micro-Raman spectroscopy and X-ray scattering measurements indicated that the GaN nanostructures had a hexagonal wurzite structure without any oxide phases. We investigated the difference in the structural properties between the GaN nanowires and nanorods. Deep-level emission bands were not observed in cathodoluminescence measurements from either the GaN nanowires or nanorods, indicating the incorporation of low-level impurities into our 1D GaN nanostructures.     

硅基镓浓度对GaN晶体膜质量的影响

采用射频磁控溅射工艺在扩镓硅基上溅射Ga2O3薄膜，再氮化反应组装GaN晶体膜，并对其生长条件进行了研究。用傅里叶红外谱仪(FTIR)、X射线衍射(XRD)、扫描电镜(SEM)、选区电子衍射(SAED)和光致发光(PL)谱对样品进行结构、形貌和发光特性的分析。测试结果表明，采用此方法可得到六方纤锌矿结构的GaN晶体膜。镓浓度在影响膜层质量方面起着不可忽视的作用，随着扩镓浓度的增加，薄膜的晶化程度和发光特性明显提高。     

Spontaneous growth of GaN nanowire nuclei on N- and Al-polar AlN: A piezoresponse force microscopy study of crystallographic polarity

The polarity of gallium nitride (GaN) nanowire nuclei grown on AlN layers was studied by piezoresponse force microscopy (PFM). N- or Al-polar AlN layers were grown by molecular beam epitaxy (MBE) on Si (111) substrates by use of Al- or N-rich growth conditions, respectively. Short and low density GaN nanowires were then grown on each AlN polarity type. PFM measurements verified the expected AlN layer polarity and further indicated that predominantly N-polar nanowires are produced for growth on both AlN polarity types. Cross-section scanning transmission electron microscopy (STEM) images further reveal that the nanowires on Al-polar AlN films are nucleated on regions in the AlN layer that contain inversion domains, which propagate into the GaN nanowire nuclei. PFM measurements were found to be a convenient technique for mapping the polarity of a statistically significant number of individual GaN nanowires.     

Application of halide vapor phase epitaxy for the growth of ultrawide band gap Ga_2O_3

Halide vapor phase epitaxy(HVPE) is widely used in the semiconductor industry for the growth of Si, GaAs, GaN, etc.HVPE is a non-organic chemical vapor deposition(CVD) technique, characterized by high quality growth of epitaxial layers with fast growth rate, which is versatile for the fabrication of both substrates and devices with wide applications. In this paper, we review the usage of HVPE for the growth and device applications of Ga_2O_3, with detailed discussions on a variety of technological aspects of HVPE. It is concluded that HVPE is a promising candidate for the epitaxy of large-area Ga_2O_3 substrates and for the fabrication of high power β-Ga_2O_3 devices.     

氮化Si基ZnO/Ga_2O_3制备GaN薄膜

利用射频磁控溅射法在Si衬底上先溅射ZnO缓冲层,接着溅射Ga2O3薄膜,然后ZnO/Ga2O3膜在管式炉中常压下通氨气进行氮化,反应自组生成GaN薄膜。XRD测量结果表明,利用该方法制备的GaN薄膜是沿c轴方向择优生长的六角纤锌矿多晶结构的薄膜,利用SEM观测了其表面形貌,PL测量结果发现了位于351nm处的室温光致发光峰。     

A review of the most recent progresses of state-of-art gallium oxide power devices

Until very recently, gallium oxide(Ga_2O_3) has aroused more and more interests in the area of power electronics due to its ultra-wide bandgap of 4.5–4.8 eV, estimated critical field of 8 MV/cm and decent intrinsic electron mobility limit of250 cm2/(V·s), yielding a high Baliga's figures-of-merit(FOM) of more than 3000, which is several times higher than GaN and SiC.In addition to its excellent material properties, potential low-cost and large size substrate through melt-grown methodology also endows β-Ga_2O_3 more potential for future low-cost power devices. This article focuses on reviewing the most recent advances ofβ-Ga_2O_3 based power devices. It will be starting with a brief introduction to the material properties of β-Ga_2O_3 and then the growth techniques of its native substrate, followed by the thin film epitaxial growth. The performance of state-of-art β-Ga_2O_3 devices, including diodes and FETs are fully discussed and compared. Finally, potential solutions to the challenges of β-Ga_2O_3 are also discussed and explored.     

氨化温度对Si基GaN纳米结构质量的影响(英文)

通过磁控溅射技术在Si(111)衬底上沉积Ga2O3/Co薄膜,然后在不同温度下氨化制得GaN纳米结构。采用X射线衍射(XRD)、傅里叶红外吸收谱(FTIR)、扫描电子显微镜(SEM)、高分辨透射电镜(HRTEM)和光致发光谱(PL)对样品的结构、形貌和光学特性进行了表征。结果显示合成的GaN纳米结构具有六方纤锌矿结构,且纳米结构的生长受温度影响很大。PL谱显示在388nm处有一强的紫外发光峰,表明其在低维激光器件方面的应用优势。同时对纳米结构的生长机制进行了简单讨论。