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AlGaN/GaN epitaxial layers were grown on 0°-tilt and 1°-tilt sapphire substrates by metalorganic chemical vapor deposition (MOCVD). With exactly the same growth conditions, it was found that dislocation density was smaller and crystal quality was better for the AlGaN/GaN epitaxial layers prepared on 1°-tilt sapphire substrate. We also found that AlGaN/GaN epitaxial layers on 1°-tilt sapphire substrate were grown with step growth mode while those on 0°-tilt substrate were grown with two-dimensional island growth. From the temperature-dependent mobility, it was found that crystal quality of the AlGaN/GaN epitaxial layer prepared on 1°-tilt sapphire substrate is better. 相似文献
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外延在蓝宝石衬底上的非掺杂GaN研究 总被引:1,自引:0,他引:1
采用改变生长条件的方法制备GaN薄膜,在(0001)面蓝宝石衬底上利用金属有机物化学气相沉积技术制备了不同样品,并借助X射线双晶衍射仪(XRD)、PL谱测试仪和光学显微镜对材料进行了分析。XRD(0002)面和(1012)面测试均表明TMGa流量为70 cm3/min时样品位错密度最低。利用该TMGa流量进一步制备了改变生长温度的样品。XRD和PL谱测试结果表明,提高生长温度有利于提高GaN样品的晶体质量和光学性能。最后,利用光学显微镜对样品的表面形貌进行了分析。 相似文献
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在柱状图形蓝宝石衬底(PSS-p)和孔状图形蓝宝石衬底(PSS-h)上外延了GaN体材料和LED结构并进行了详细对比和分析.X射线衍射仪(XRD)和原子力显微镜(AFM)测试结果表明,PSS-h上体材料的晶体质量和表面形貌都优于PSS-p上体材料的特性,通过断面扫面电子显微镜(SEM)照片看出PSS-h上GaN的侧向生长是导致这种差异的原因.另外,基于PSS-p和PSS-h上外延的LED材料制作而成的器件结果表明,其20?mA下光功率水平相比普通蓝宝石衬底(CSS)分别提高了46%和33%.通过变温光荧光
关键词:
蓝宝石图形衬底
氮化镓
发光二极管
侧向生长 相似文献
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在实验优化MBE工艺条件的基础上,采用蓝宝石(0001)邻晶面衬底制备出了具有较高质量的GaN薄膜.XRD分析表明邻晶面衬底生长的GaN薄膜晶体结构质量明显提高,AFM表征结果显示邻晶面生长的样品表面形貌显著改善.蓝宝石衬底GaN薄膜的瞬态光电导弛豫特性对比实验研究发现,常规衬底生长的GaN薄膜光电导弛豫特性出现双分子复合、单分子复合和弛豫振荡三个过程,持续时间分别为0.91,7.7和35.5ms;蓝宝石邻晶面衬底生长的GaN薄膜光电导弛豫过程主要是双分子复合和单分子复合过程,持续时间分别为0.78和14ms.理论分析表明MBE生长GaN薄膜的持续光电导效应主要起源于本生位错缺陷引发的深能级.
关键词:
邻晶面蓝宝石衬底
GaN薄膜
瞬态光电导
弛豫特性 相似文献
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In this study, we report growth and characterization of GaN layers on (1 0 0)- and (1 1 1)-oriented silicon-on-insulator (SOI) substrates. Using metalorganic chemical vapor deposition (MOCVD) technique, GaN layers are grown on KOH treated Si (1 0 0) overlayers of thin SIMOX SOI substrates. Growth of GaN on such surface with an AlN buffer leads to c-axis orientated textured GaN. This is evident from high-resolution X-ray diffraction (HRXRD) measurement, which shows a much broader rocking curve linewidth. Significantly enhanced photoluminescence (PL) intensity and partial stress relaxation is observed in GaN layers grown on these SOI substrates. Furthermore, GaN grown on (1 1 1)-oriented bonded SOI substrates shows good surface morphology and improved optical quality. Micro-Raman, micro-PL, and HRXRD measurements reveal single crystalline hexagonal GaN oriented along (0 0 0 1) direction. We also report growth and characterization of InGaN/GaN multi-quantum well structures on (1 1 1)-oriented bonded SOI. Such an approach to realize nitride epilayers would be useful to fabricate GaN-based micro-opto-electromechanical systems (MOEMS) and sensors. 相似文献
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The effect of single A1GaN interlayer on the structural properties of GaN epilayers grown on Si (111) substrates 下载免费PDF全文
High-quality and nearly crack-free GaN epitaxial layer was obtained
by inserting a single AlGaN interlayer between GaN epilayer and
high-temperature AlN buffer layer on Si (111) substrate by
metalorganic chemical vapor deposition. This paper investigates the
effect of AlGaN interlayer on the structural properties of the
resulting GaN epilayer. It confirms from the optical microscopy and
Raman scattering spectroscopy that the AlGaN interlayer has a
remarkable effect on introducing relative compressive strain to the
top GaN layer and preventing the formation of cracks. X-ray
diffraction and transmission electron microscopy analysis reveal
that a significant reduction in both screw and edge threading
dislocations is achieved in GaN epilayer by the insertion of AlGaN
interlayer. The process of threading dislocation reduction in both
AlGaN interlayer and GaN epilayer is demonstrated. 相似文献
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HE Tao LI Hui DAI LongGui WANG XiaoLi CHEN Yao MA ZiGuang XU PeiQiang JIANG Yang WANG Lu JIA HaiQiang WANG WenXin & CHEN Hong Beijing National Laboratory of Condensed Matter 《中国科学:物理学 力学 天文学(英文版)》2011,(3)
Nonpolar a-plane (110) GaN films have been grown on r-plane (102) sapphire by metal-organic chemical vapor deposition (MOCVD) under different growth pressures. The as-grown films are investigated by optical microscopy, high-resolution X-ray diffraction (HRXRD) and Raman scattering. As growth pressure rises from 100 mbar to 400 mbar, the surface gets rougher, and the in-plane XRD full width at half maximum (FWHM) along the c-axis [0001] increases while that along the m-axis [100] decreases. Meanwhile, res... 相似文献
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Metal organic chemical vapor deposition (MOCVD) has been used to grow vanadium-doped GaN (GaN:V) on c-sapphire substrate using VCl4 as the V source. The as-grown GaN:V exhibited a saturated magnetic moment (Ms) of 0.28 emu/cm3 at room temperature. Upon high-temperature annealing treatment at 1100 °C for 7 min under N2 ambient, the Ms of the GaN:V increased by 39.28% to 0.39 emu/cm3. We found that rapid thermal annealing leads to a remarkable increase in surface roughness of the V-doped GaN as well as the electron concentration. The annealing also leads to a significant increase in the Curie temperature (TC), we have identified Curie temperatures about 350 K concluded from the difference between the field-cooled and zero-field-cooled magnetizations. Structure characterization by x-ray diffraction indicated that the ferromagnetic properties are not a result of secondary magnetic phases. 相似文献
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Zheng LiYuxuan Jiang Tongjun Yu Zhiyuan YangYuebin Tao Chuanyu JiaZhizhong Chen Zhijian YangGuoyi Zhang 《Applied Surface Science》2011,257(18):8062-8066
The surface temperature of cone-shaped patterned sapphire substrate (PSS) in GaN epitaxial growth by MOCVD and its relation to forced convection conditions and substrate surface topography were systematically investigated. Calculations using finite element method (FEM) exhibited that increase of substrate thickness would reduce surface temperature variation on PSS in typical growth condition. A hydrodynamics model under different chamber conditions is established, suggesting that carrier gas's velocity V∞ plays a significant role on surface temperature of PSS in comparison with planar substrate. Also, carrier gas's pressure Pcarrier is found to be another important factor on surface thermal distribution. Results of temperatures of surface with different pattern topographies suggested that an ideal PSS structure can confine the in-cell temperature discrepancy on surface into less than 0.4 K. Pattern scales of PSS and their influence on surface temperature variation were also discussed. 相似文献
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Y. Tokuda Y. Matsuoka H. Ueda O. Ishiguro N. Soejima T. Kachi 《Superlattices and Microstructures》2006,40(4-6):268
Electron traps in n-type GaN layers grown homoepitaxially by MOCVD on free-standing GaN substrates have been characterized using DLTS for vertical Schottky diodes. Two free-standing HVPE GaN substrates (A and B), obtained from two different sources, are used. The Si-doped GaN layers with the thickness of 5 μm are grown on an area of 0.9×0.9 cm2 of substrate A and on an area of 1×1 cm2 of substrate B. Two traps labeled B1 and B2 are observed with trap B2 dominant in GaN on both substrates. There exist no dislocation-related traps which have been previously observed in MOCVD GaN on sapphire. This might be correlated to the reduction in dislocation density due to the homoepitaxial growth. However, it is found that there is a large variation, more than an order of magnitude, in trap B2 concentration and that the B2 spatial distributions are different between the two substrates used. 相似文献
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The growth of GaP layer on GaN with and without buffer layers by metal-organic chemical vapour deposition (MOCVD) has been studied. Results indicate that the GaP low temperature buffer layer can provide a high density of nucleation sites for high temperature (HT) GaP growth. These sites can promote the two-dimensional (2D) growth of HT GaP and reduce the surface roughness. A GaP single crystal layer grown at 680°C is obtained using a 40-nm thick GaP buffer layer. The full-width at half-maximum (FWHM) of the (111) plane of GaP layer, measured by DCXRD, is 560 arcsec. The GaP layer grown on GaN without low temperature GaP buffer layer shows a rougher surface. However, the FWHM of the (111) plane is 408 arcsec, which is the indication of better crystal quality for the GaP layer grown on GaN without a low temperature buffer layer. Because it provides less nucleation sites grown at high growth temperature, the three-dimensional (3D) growth is prolonged. The crystalline quality of GaP is lightly improved when the surface of GaN substrate is pretreated by PH3 , while it turned to be polycrystalline when the substrate is pretreated by TEGa. 相似文献
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Yanhui Xing Jun Han Jun Deng Jianjun Li Chen Xu Guangdi Shen 《Applied Surface Science》2009,255(12):6121-6124
GaN layer on c-plane misoriented sapphire, grown by metal organic chemical vapor deposition, has been studied. It was observed that the random and non-uniform distribution of the step was caused by the step reconstruction for GaN grown on 0° sapphire by atomic force microscopy. The image quality parameter analysis of electron back-scatter diffraction indicated that the strains were reduced for GaN grown on 0.2° and 0.3° sapphire, and optical and electrical properties were improved. The electroluminescence intensity of LED grown on 0.2° and 0.3° sapphire was 2 times as that of 0° sapphire. 相似文献
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ZHANG YuChao XING ZhiGang MA ZiGuang CHEN Yao DING GuoJian XU PeiQiang DONG ChenMing CHEN Hong & LE XiaoYun School of Physics Nuclear Energy Engineering Beihang University Beijing China Renewable Energy Laboratory 《中国科学:物理学 力学 天文学(英文版)》2010,(3)
GaN epifilms are grown on the patterned sapphire substrates (PSS) (0001) and the conventional sapphire substrates (CSS) (0001) by metal-organic chemical vapor deposition (MOCVD) using a novel two-step growth. High resolution X-ray diffraction (HR-XRD) is used to investigate the threading dislocation (TD) density of the GaN epifilms. The TD density is calculated from the ω-scans full width at half maximum (FWHM) results of HR-XRD. The edge dislocation destiny of GaN grown on the PSS is 2.7×108 cm-2, which is less than on the CSS. This is confirmed by the results of atomic force microscopy (AFM) measurement. The lower TD destiny indicates that the crystalline quality of the GaN epifilms grown on the PSS is improved compared to GaN epifilms grown on the CSS. The residual strains of GaN grown on the PSS and CSS are compared by Raman Scattering spectra. It is clearly seen that the residual strain in the GaN grown on PSS is lower than on the CSS. 相似文献
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The influence of AlN/GaN superlattice intermediate layer on the properties of GaN grown on Si(111) substrates 下载免费PDF全文
AlN/GaN superlattice buffer is inserted between GaN epitaxial layer
and Si substrate before epitaxial growth of GaN layer. High-quality
and crack-free GaN epitaxial layers can be obtained by inserting
AlN/GaN superlattice buffer layer. The influence of AlN/GaN
superlattice buffer layer on the properties of GaN films are
investigated in this paper. One of the important roles of the
superlattice is to release tensile strain between Si substrate and
epilayer. Raman spectra show a substantial decrease of in-plane
tensile strain in GaN layers by using AlN/GaN superlattice buffer
layer. Moreover, TEM cross-sectional images show that the densities
of both screw and edge dislocations are significantly reduced. The
GaN films grown on Si with the superlattice buffer also have better
surface morphology and optical properties. 相似文献
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On semipolar epitaxial ZnO grown by chemical vapor deposition consists of two distinct orientations as evidenced by transmission electron microscopy and X‐ray diffraction. The initially grown ZnO on GaN follows the GaN lattice with the epitaxial relationship of // and The other oriented ZnO domains then grow on faceted with and with good coherency with the ‐oriented grains. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
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利用金属有机物化学气相沉积技术在蓝宝石衬底上低温生长GaN:Mg薄膜,对不同源流量的GaN:Mg材料特性进行优化研究.研究表明二茂镁(CP2Mg)和三甲基镓(TMGa)物质的量比([CP2Mg]/[TMGa])在1.4×10-3—2.5×10-3范围内,随[CP2Mg]/[TMGa]增加,晶体质量提高,空穴浓度线性增加.当[CP2Mg]/[TMGa]为2.5×10-3时获得空穴浓度与在较高温度生长获得的空穴浓度相当,且薄膜表面较粗糙.采用[CP2Mg]/[TMGa]为2.5×10-3的p型GaN层制备的发光二极管,在注入电流为20mA时,输出光强提高了17.2%. 相似文献