共查询到19条相似文献,搜索用时 62 毫秒
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GaN在(0001)方向是一种极性极强的半导体材料,它具有极强的表面特征,是目前发现的最好的压电材料,而GaN的极性呈现出体材料的特征,它的测量要用一些特殊的方法,它的不同特征也给我们提供了广泛的应用前景.总结了到目前为止国外这一方面的研究结果. 相似文献
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采用MOCVD技术在r面蓝宝石衬底上采用两步AlN缓冲层法外延制备了a面GaN薄膜.利用高分辨X射线衍射技术和Raman散射技术分析了样品的质量以及外延膜中的残余应力.实验结果表明:样品的(1120)面的X射线双晶摇摆曲线的半峰宽仅为0.193°,Raman光谱中E2高频模的半峰宽仅为3.9cm-1,这些说明a面GaN薄膜具有较好的晶体质量;X射线研究结果表明样品与衬底的位相关系为:[11(2)0]GaN ||[1(1)02]sapphire,[0001]Gan||[(11)01]sapphire和[(11)00]GaN[11(2)0]sapphire;高分辨X射线和Raman散射谱的残余应力研究表明,采用两步AlN缓冲层法制备的a面GaN薄膜在平面内的残余应力大小与用低温GaN缓冲层法制备的a面GaN薄膜不同,我们认为这是由引入AlN带来的晶格失配和热失配的变化引起的. 相似文献
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采用MOCVD技术在r面蓝宝石衬底上采用两步AlN缓冲层法外延制备了a面GaN薄膜.利用高分辨X射线衍射技术和Raman散射技术分析了样品的质量以及外延膜中的残余应力.实验结果表明:样品的(1120)面的X射线双晶摇摆曲线的半峰宽仅为0.193°,Raman光谱中E2高频模的半峰宽仅为3.9cm-1,这些说明a面GaN薄膜具有较好的晶体质量;X射线研究结果表明样品与衬底的位相关系为:[11(2)0]GaN ||[1(1)02]sapphire,[0001]Gan||[(11)01]sapphire和[(11)00]GaN[11(2)0]sapphire;高分辨X射线和Raman散射谱的残余应力研究表明,采用两步AlN缓冲层法制备的a面GaN薄膜在平面内的残余应力大小与用低温GaN缓冲层法制备的a面GaN薄膜不同,我们认为这是由引入AlN带来的晶格失配和热失配的变化引起的. 相似文献
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用原子力显微镜和扫描电镜相结合的方法表征了KOH腐蚀后的Si掺杂GaN外延层中的位错腐蚀坑.根据腐蚀坑的不同形状和在表面的特定位置可将其分成三种类型,它们的起源可由一个关于腐蚀机制的模型加以解释.纯螺位错易于沿着由它结束的表面阶梯被腐蚀,形成一个小的Ga极性面以阻止进一步的纵向腐蚀,因而其腐蚀坑是位于两个表面阶梯交结处的截底倒六棱椎.纯刃位错易于沿位错线被腐蚀,因而其腐蚀坑是沿着表面阶梯分布的尖底倒六棱椎.极性在GaN的腐蚀过程中起了重要作用. 相似文献
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用原子力显微镜和扫描电镜相结合的方法表征了KOH腐蚀后的Si掺杂GaN外延层中的位错腐蚀坑.根据腐蚀坑的不同形状和在表面的特定位置可将其分成三种类型,它们的起源可由一个关于腐蚀机制的模型加以解释.纯螺位错易于沿着由它结束的表面阶梯被腐蚀,形成一个小的Ga极性面以阻止进一步的纵向腐蚀,因而其腐蚀坑是位于两个表面阶梯交结处的截底倒六棱椎.纯刃位错易于沿位错线被腐蚀,因而其腐蚀坑是沿着表面阶梯分布的尖底倒六棱椎.极性在GaN的腐蚀过程中起了重要作用. 相似文献
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半极性GaN材料的研究在光电器件和电子器件领域有重要意义.采用选区外延生长技术在Si衬底上生长半极性GaN材料,并制备肖特基势垒二极管(SBD).通过测量SBD在不同温度下的Ⅰ-Ⅴ特性曲线,观察到电流的大小随着温度的增加而增加,且受反向偏压影响,证明半极性GaN基SBD的电流传输机制为热电子场发射模型.光致发光光谱和X射线光电子能谱测试进一步表明,相比极性c面GaN材料,半极性GaN材料表面存在较高的氧杂质原子浓度和氮空位,此为半极性GaN肖特基特性偏离热电子发射模型的主要因素. 相似文献
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在3英寸(1英寸=2.54 cm)SiC衬底上采用金属有机物化学气相沉积(MOCVD)法生长GaN外延材料。研究了AlN缓冲层的应变状态对GaN外延层应变状态和质量的影响。使用原子力显微镜和高分辨率X射线双晶衍射仪观察样品表面形貌,表征外延材料质量的变化,使用高分辨喇曼光谱仪观察外延材料应力的变化,提出了基于外延生长的应变变化模型。实验表明,GaN外延层的张应变随着AlN缓冲层应变状态的由压变张逐渐减小,随着GaN张应力的逐渐减小,GaN位错密度也大大减少,表面形貌也逐渐变好。 相似文献
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用电子束蒸发方法在Si(111)衬底上蒸发了Au/Cr和Au/Ti/Al/Ti 两种金属缓冲层,然后在金属缓冲层上用气源分子束外延(GSMBE)生长GaN. 两种缓冲层的表面都比较平整和均匀,都是具有Au(111)面择优取向的立方相Au层. 在Au/Cr/Si(111)上MBE生长的GaN,生长结束后出现剥离. 在Au/Ti/Al/Ti/Si(111)上无AlN缓冲层直接生长GaN,得到的是多晶GaN;先在800℃生长一层AlN缓冲层,然后在710℃生长GaN,得到的是沿GaN(0001)面择优取向的六方相GaN. 将Au/Ti/Al/Ti/Si(111)在800℃下退火20min,金属层收缩为网状结构,并且成为多晶,不再具有Au(111)方向择优取向. 相似文献
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Strong yellow luminescence (YL) was found in GaN grown by the halide vapor phase epitaxy technique, using an NH3-HCl-GaCl-N2-H2 growth chemistry. The low-temperature (less than 100K) thermal activation energy of the yellow luminescence was determined
to be ∼18 meV, which indicates that a shallow donor, rather than a ‘shallow’ acceptor, was involved in observed radiative
transition. The temperature dependence of the YL peak energy and the shape of the YL band imply that there are multiple recombination
channels involved in the YL band. The ratio of integrated intensity of yellow-to-bandedge luminescence decreased with an increase
of HCl (and hence GaCl and growth rate) in the growth ambient. 相似文献
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使用气相沉积SiO2和普通光刻以及湿法腐蚀方法,在C面蓝宝石上开出不同尺寸的正方形窗口,在窗口区域中露出衬底,然后使用氢化物气相外延(HVPE)方法选区外延GaN薄膜.采用光学显微镜、原子力显微镜(AFM)、扫描电子显微镜(SEM)、高分辨率双晶X射线衍射(DCXRD)和喇曼谱测试(Raman shift)对薄膜进行分析.结果表明,在C面蓝宝石衬底上独立的正方形窗口区域中外延生长的,厚度约20μm的GaN薄膜,当窗口面积为100μm×100μm时,GaN表面无裂纹;而当窗口面积为300μm×300μm和500μm×500μm时,GaN表面有裂纹.随着窗口面积的减小,GaN双晶衍射摇摆曲线的(0002)峰的半高宽(FWHM)减小,表明晶体的质量更好,最小的半高宽为530".从正方形窗口区的角上到边缘再到中心,GaN的面内压应力逐渐减小,分析认为这与OaN横向外延区(ELO区)与SiO2掩膜之间的相互作用,以及窗口区到ELO区的线位错的90"扭转有关. 相似文献
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使用气相沉积SiO2和普通光刻以及湿法腐蚀方法,在C面蓝宝石上开出不同尺寸的正方形窗口,在窗口区域中露出衬底,然后使用氢化物气相外延(HVPE)方法选区外延GaN薄膜.采用光学显微镜、原子力显微镜(AFM)、扫描电子显微镜(SEM)、高分辨率双晶X射线衍射(DCXRD)和喇曼谱测试(Raman shift)对薄膜进行分析.结果表明,在C面蓝宝石衬底上独立的正方形窗口区域中外延生长的,厚度约20μm的GaN薄膜,当窗口面积为100μm×100μm时,GaN表面无裂纹;而当窗口面积为300μm×300μm和500μm×500μm时,GaN表面有裂纹.随着窗口面积的减小,GaN双晶衍射摇摆曲线的(0002)峰的半高宽(FWHM)减小,表明晶体的质量更好,最小的半高宽为530".从正方形窗口区的角上到边缘再到中心,GaN的面内压应力逐渐减小,分析认为这与OaN横向外延区(ELO区)与SiO2掩膜之间的相互作用,以及窗口区到ELO区的线位错的90"扭转有关. 相似文献
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Kai Qiu X.H. Li F. Zhong Z.J. Yin X.D. Luo C.J. Ji Q.F. Han J.R. Chen X.C. Cao X.J. Xie Y.Q. Wang 《Journal of Electronic Materials》2007,36(4):436-441
This paper reports the properties of GaN grown by the hydride vapor-phase epitaxy (HVPE) technique on buffer layers with different
polarities. The N-, mixed-, and Ga-polarity buffer layers were grown by molecular-beam epitaxy (MBE) on sapphire (0001) substrates;
then, thicker GaN epilayers were grown on these by HVPE. The surface morphology, structural, and optical properties of these
HVPE-GaN epilayers were characterized by atomic force microscopy (AFM), x-ray diffraction (XRD), scanning electron microscopy,
and photoluminescence (PL) spectroscopy. The results indicate that the crystallinity of these HVPE-GaN epilayers depends on
the polarity of the buffer layer. 相似文献
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YEHao-hua YUGuang-hui LEIBen-lian QIMing LIAi-zhen 《半导体光子学与技术》2005,11(1):28-31
Thick GaN films were grown on the sapphire substrate by hydride vapour phase epitaxy. The properties of GaN films were found to be significantly influenced by the duration of exposing the sapphire substrate to ammonia prior to the GaN growth initiation. The crystalline quality of GaN films revealed by high resolution X-ray diffraction were strongly dependent on the nitridation time, which determined substrate surface topography. The different nitridation schemes strongly affected the morphology of GaN overlayers resulting in the blue shift of the main excitonic peak in photoluminescence spectra at room temperature. 相似文献
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Growth of GaN on porous SiC and GaN substrates 总被引:1,自引:0,他引:1
C. K. Inoki T. S. Kuan C. D. Lee Ashutosh Sagar R. M. Feenstra D. D. Koleske D. J. Díaz P. W. Bohn I. Adesida 《Journal of Electronic Materials》2003,32(8):855-860
We have studied the growth of GaN on porous SiC and GaN substrates, employing both plasma-assisted molecular-beam epitaxy
(PAMBE) and metal-organic chemical-vapor deposition (MOCVD). For growth on porous SiC, transmission electron microscopy (TEM)
observations indicate that the epitaxial-GaN growth initiates primarily from surface areas between pores, and the exposed
surface pores tend to extend into GaN as open tubes and trap Ga droplets. The dislocation density in the GaN layers is similar
to, or slightly less than, that observed in layers grown on nonporous substrates. For the case of GaN growth on porous GaN,
the overgrown layer replicates the underlying dislocation structure (although considerable dislocation reduction can occur
as this overgrowth proceeds, independent of the presence of the porous layer). The GaN layers grown on a porous SiC substrate
were found to be mechanically more relaxed than those grown on nonporous substrates; electron-diffraction patterns indicate
that the former are free of misfit strain or are even in tension after cooling to room temperature. 相似文献
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