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1.
A high temperature A1N template was grown on sapphire substrate by metalorganic chemical vapor deposition. AFM results showed that the root mean square of the surface roughness was just 0.11 nm. Optical transmission spectrum and high resolution X-ray diffraction (XRD) characterization both proved the high quality of the A1N template. The XRD (002) rocking curve full width at half maximum (FWHM) was about 53.7 arcsec and (102) FWHM was about 625 arcsec. The densities of screw threading dislocations (TDs) and edge TDs were estimated to be~6×10~6 cm~(-2) and ~4.7×10~9 cm~(-2). A1GaN of A1 composition 80.2% was further grown on the A1N template. The RMS of the surface roughness was about 0.51 nm. XRD reciprocal space mapping was carried out to accurately determine the Al composition and relaxation status in the A1GaN epilayer. The XRD (002) rocking curve FWHM of the A1GaN epilayer was about 140 arcsec and (102) FWHM was about 537 arcsec. The density of screw TDs was estimated to be ~4×10~7 cm~(-2) and that of edge TDs was~3.3×10~9 cm~(-2). These values all prove the high quality of the A1N template and AlGaN epilayer. 相似文献
2.
采用脉冲直流磁控溅射方法在Si(100)衬底上制备了ScAlN薄膜。以溅射的ScAlN作为缓冲层,在Si(100)衬底上用金属有机化学气相沉积(MOCVD)技术外延了GaN薄膜。使用高分辨X射线衍射、原子力显微镜和拉曼光谱研究了ScAlN缓冲层的厚度对ScAlN缓冲层和GaN外延层的影响。研究结果表明,ScAlN缓冲层的厚度是影响GaN薄膜晶体质量的重要因素。随着ScAlN厚度的增加,ScAlN的(002)面X射线衍射摇摆曲线半高宽持续减小,GaN的(002)面X射线衍射摇摆曲线半高宽先减小后增大。当ScAlN缓冲层厚度为500nm时,得到的GaN晶体质量最好,其中GaN(002)面的X射线衍射摇摆曲线半高宽为0.38°,由拉曼光谱计算得到的张应力为398.38MPa。 相似文献
3.
A. E. Nikolaev S. V. Rendakova I. P. Nikitina K. V. Vassilevski V. A. Dmitriev 《Journal of Electronic Materials》1998,27(4):288-291
6H-SiC/GaN pn-heterostructures were grown by subsequent epitaxial growth of p-SiC by low temperature liquid phase epitaxy
(LTLPE) and n-GaN by hydride vapor phase epitaxy (HVPE). For the first time, p-type epitaxial layers grown on 6H-SiC wafers
were used as substrates for GaN HVPE growth. The GaN layers exhibit high crystal quality which was determined by x-ray diffraction.
The full width at a half maximum (FWHM) for the ω-scan rocking curve for (0002) GaN reflection was ∼120 arcsec. The photoluminescence
spectra for these films were dominated by band-edge emission. The FWHM of the edge PL peak at 361 nm was about 5 nm (80K). 相似文献
4.
K. Doverspike L. B. Rowland D. K. Gaskill J. A. Freitas 《Journal of Electronic Materials》1995,24(4):269-273
This paper presents a comparative study of the properties of GaN grown by organometallic vapor phase epitaxy, using both a
GaN and A1N buffer layer, as a function of sapphire orientation (c-plane vs a-plane). Results are presented for varying the
thickness of the buffer layer, varying the growth temperature of the GaN film, and also varying the ammonia/trimethylgallium
mass flow ratio. The electron Hall mobilities of GaN films grown on an A1N buffer layer were, in general, higher compared
to films grown using a GaN buffer layer. In addition, growth on a-plane sapphire resulted in higher quality films (over a
wider range of buffer thicknesses) than growth on c-plane sapphire. The room temperature electron mobilities were also found
to be dependent on, not only the growth temperature, but also the ammonia/trimethylgallium mass flow ratio. 相似文献
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We study the plasma-assisted molecular beam epitaxy of cubic GaN on GaAs(OOl) substrates by means ofin-situ reflection high-energy electron diffraction. The epilayers are characterized by x-ray diffraction, photoluminescence, and
Hall measurements, and it is found that the overall best films are grown under a N/Ga ratio close to one. For anin-situ determination of the N/Ga ratio, the growth kinetics is studied via surface reconstruction transitions. The effective N flux
giving rise to growth is measured using the transient behavior of the half-order diffraction streak intensity for various
plasma operating conditions. 相似文献
9.
Ching-Ting Lee Hong-Wei Chen Fu-Tsai Hwang Hsin-Ying Lee 《Journal of Electronic Materials》2005,34(3):282-286
By using a He-Cd laser in a chemical solution of H3PO4 with a pH value of 3.5, Ga oxide films were directly grown on n-type GaN. From the energy-dispersive spectrometer (EDS) measurement
and x-ray diffraction (XRD) measurement, the grown Ga oxide film was identified as (104) α-Ga2O3 structure. A small amount of phosphors existed and bonded with oxygen on the grown films. The as-grown films were amorphous.
From the XRD analysis, it is evident that annealing of the α-Ga2O3 films led to a change in the microstructure from an amorphous to a polycrystalline phase. In addition, the as-grown low-density
films gradually became dense films during the annealing process. Furthermore, the surface roughness of the annealed films
also gradually decreased. Hexagonal pinholes on the grown films were observed. The density of the hexagonal pinholes was similar
to the defect density of the n-type GaN. From the cross-sectional transmission electron microscopy (TEM) micrographs, it is
evident that the hexagonal pinholes originated from defects in the n-type GaN. 相似文献
10.
InAlN epilayers were grown on high quality GaN and A1N templates with the same growth parameters. Measurement results showed that two samples had the same In content of~16%,while the crystal quality and surface topography of the InAlN epilayer grown on the AlN template,with 282.3"(002) full width at half maximum (FWHM) of rocking curve,313.5"(102) FWHM,surface roughness of 0.39 nm and V-pit density of 2.8×108 cm-2,were better than that of the InAlN epilayer grown on the GaN template,309.3",339.1",0.593 nm and 4.2×108 cm-2.A primary conclusion was proposed that both the crystal quality and the surface topography of the InAlN epilayer grown on the AlN template were better than that of the InAlN epilayer grown on the GaN template. Therefore,the AlN template was a better choice than the GaN template for getting high quality InAlN epilayers. 相似文献
11.
J. N. Dai Z. H. Wu C. H. Yu Q. Zhang Y. Q. Sun Y. K. Xiong X. Y. Han L. Z. Tong Q. H. He F. A. Ponce C. Q. Chen 《Journal of Electronic Materials》2009,38(9):1938-1943
In this work, we have comparatively investigated the effects of the GaN, AlGaN, and AlN low-temperature buffer layers (BL)
on the crystal quality of a-plane GaN thin films grown on r-plane sapphire substrates. Scanning electron microscopy images of the a-plane GaN epilayers show that using an AlGaN BL can significantly reduce the density of surface pits. The full-width at half-maximum
values of the x-ray rocking curve (XRC) are 0.19°, 0.36°, and 0.48° for the films grown using Al0.15Ga0.85N, GaN, and AlN BLs, respectively, indicating that an AlGaN BL can effectively reduce the mosaicity of the films. Room-temperature
photoluminescence shows that the AlGaN BL results in lower impurity incorporation in the subsequent a-plane GaN films, as compared with the case of GaN and AlN BLs. The higher crystal quality of a-plane GaN films produced by the Al0.15Ga0.85N BL could be due to improvement of BL quality by reducing the lattice mismatch between the BL and r-sapphire substrates, while still keeping the lattice mismatch between the BL and epitaxial a-plane GaN films relatively small. 相似文献
12.
锥形图形衬底上氮化镓薄膜生长和表征 总被引:1,自引:1,他引:0
Jing Liang Xiao Hongling Wang Xiaoliang Wang Cuimei Deng Qingwen Li Zhidong Ding Jieqin Wang Zhanguo Hou Xun 《半导体学报》2013,34(11):113002-5
GaN films are grown on cone-shaped patterned sapphire substrates(CPSSs)by metal-organic chemical vapor deposition,and the influence of the temperature during the middle stage of GaN growth on the threading dislocation(TD)density of GaN is investigated.High-resolution X-ray diffraction(XRD)and cathodeluminescence(CL)wereusedtocharacterizetheGaNfilms.TheXRDresultsshowedthattheedge-typedislocation density of GaN grown on CPSS is remarkably reduced compared to that of GaN grown on conventional sapphire substrates(CSSs).Furthermore,whenthegrowthtemperatureinthemiddlestageofGaNgrownonCPSSdecreases,the full width at half maximum of the asymmetry(102)plane of GaN is reduced.This reduction is attributed to the enhancement of vertical growth in the middle stage with a more triangular-like shape and the bending of TDs.The CL intensity spatial mapping results also showed the superior optical properties of GaN grown on CPSS to those of GaN on CSS,and that the density of dark spots of GaN grown on CPSS induced by nonradiative recombination is reduced when the growth temperature in the middle stage decreases. 相似文献
13.
Moon-Ho Ham Min-Chang Jeong Woo-Young Lee Jae-Min Myoung Jeung-Mi Lee Joon-Yeon Chang Suk-Hee Han 《Journal of Electronic Materials》2004,33(2):114-117
We present the magnetic and magnetotransport properties of epitaxial (Ga,Mn)N films with nominal Mn concentration (x=0.1–0.73%)
grown by plasma-enhanced molecular beam epitaxy (PEMBE). X-ray diffraction (XRD) reveals that (Ga,Mn)N has the single-phase
wurtzite structure without secondary phases. The epitaxial (Ga,Mn)N films were found to exhibit n-type conductivity, ferromagnetic
ordering with Curie temperature in the range 550–700 K, and in-plane magnetic anisotropy. The negative magnetoresistance (MR)
was observed at temperatures below 50 K and was found to gradually increase with decreasing temperature. 相似文献
14.
Zuzanna Liliental-Weber C. Kisielowski S. Ruvimov Y. Chen J. Washburn I. Grzegory M. Bockowski J. Jun S. Porowski 《Journal of Electronic Materials》1996,25(9):1545-1550
This paper describes TEM characterization of bulk GaN crystals grown at 1500–1800Kin the form of plates from a solution of
atomic nitrogen in liquid gallium under high nitrogen pressure (up to 20 kbars). The x-ray rocking curves for these crystals
were in the range of 20–30 arc-sec. The plate thickness along thec axis was about 100 times smaller than the nonpolar growth directions. A substantial difference in material quality was observed
on the opposite sides of the plates normal to thec direction. On one side the surface was atomically flat, while on the other side the surface was rough, with pyramidal features
up to 100 nm high. The polarity of the crystals was determined using convergent-beam electron diffraction. The results showed
that, regarding the long bond between Ga and N along the c-axis, Ga atoms were found to be closer to the flat side of the
crystal, while N atoms were found to be closer to the rough side. Near the rough side, within 1/10 to 1/4 of the plate thickness,
there was a high density of planar defects (stacking faults and dislocation loops decorated by Ga/void precipitates). A model
explaining the defect formation is proposed. 相似文献
15.
载气流量对HVPE外延生长GaN膜光学性质的影响 总被引:2,自引:0,他引:2
研究了利用水平氢化物气相外延 (HVPE)系统在蓝宝石衬底上外延氮化镓 (Ga N)的生长规律 ,重点研究了作为载气的氮气流量对 Ga N膜的结构及光学性质的影响。观察到载气流量对预反应的强弱有很大影响 ,外延膜的质量和生长速度对载气流量极为敏感。当载气流量较小时 ,样品的 X射线衍射谱 (XRD)中出现了杂峰(1 0 -1 1 )和 (1 1 -2 0 ) ,相应的光致发光谱 (PL)中出现了黄带 (YL) ,靠近带边有杂质态。而当载气流量增大时 ,样品质量改善。Ga N外延膜的结构和光学性质的相关性表明深能级的黄带与生长过程中产生的非 c轴方向晶面有关 ,据此我们推测 :Ga空位与束缚在 (1 0 -1 1 )和 (1 1 -2 0 )等原子面上的杂质构成复合结构 ,这些复合结构所产生的深能级对黄带的发射有贡献 ;由于预反应使生长过程中混入的附加产物及杂质对带边发射有重要影响 相似文献
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W. K. Fong C. F. Zhu B. H. Leung C. Surya B. Sundaravel E. Z. Luo J. B. Xu I. H. Wilson 《Microelectronics Reliability》2002,42(8):1179-1184
A small indium flux was used as a surfactant during the growth of gallium nitride by rf-plasma assisted molecular beam epitaxy. The effects of the In surfactant on the optical and structural properties of undoped GaN were studied by photoluminescence (PL), X-ray diffraction, atomic force microscopy (AFM), and Rutherford backscattering spectrometry (RBS). PL studies show that the use of In surfactant is beneficial to the reduction of deep-level defects. The X-ray rocking curves demonstrate a 20% decrease in the full width at half maximum value for the films grown with In surfactant. AFM studies show that the root mean squared surface roughness for films grown with and without In surfactant are 5.86 and 6.99 nm respectively indicating significant improvement in surface morphology. The improved surface morphology is attributed to the enhanced 2-dimensional growth promoted by the application of In surfactant. RBS studies show that the χmin values along [0 0 0 1] direction are 2.06% and 2.16% for the samples grown with and without In surfactant respectively. Off-normal ion channeling studies were performed to further investigate the effects of In surfactant on the crystallinity. It is found that the number density of stacking faults is smaller for the sample grown with In surfactant compared to the one grown without In surfactant. However, defect analysis shows that dislocations are found in the sample grown with In surfactant in contrary to the one grown without In surfactant. We speculate that there is a thickness limit of GaN grown with In surfactant and the thickness of our samples exceed this limit, leading to the presence of dislocation. 相似文献
18.
采用化学方法腐蚀部分 c-面蓝宝石衬底,在腐蚀区域形成一定的图案,利用 LP-MOCVD 在此经过表面处理的蓝宝石衬底上外延生长 GaN 薄膜.采用高分辨率双晶X射线衍射(DCXRD)、光致发光光谱(PL)、透射光谱分析GaN薄膜的晶体质量和光学质量.分析结果表明,CaN 薄膜透射谱反映出的 CaN 质量与 X射线双晶衍射测量的结果一致,即透射率越大,半高宽越小,结晶质量越好;对蓝宝石衬底进行前处理可以大大改善GaN薄膜的晶体质量和光学质量,其(0002)面及(1012)面XRD半高宽(FWHM)分别降低到 208.80arcsec 及 320.76arcsec,而且其光致发光谱中的黄光带几乎可以忽略. 相似文献
19.
研究了采用高频PlasmaCVD技术在较低温度下(300—400℃)生长以GaN为基的Ⅲ-Ⅴ族氮化物的可行性,在蓝宝石衬底上生长了GaN缓冲层.热处理后的光致发光谱和X光衍射表明,生长的GaN缓冲层为立方相,带边峰位于3.15eV.在作者实验的范围内,最优化的TMGa流量为0.08sccm(TMAm=10sccm时),XPS分析结果表明此时的Ga/N比为1.03.这是第一次在高Ⅴ/Ⅲ比下得到立方GaN.相同条件下石英玻璃衬底上得到的立方GaN薄膜,黄光峰很弱,晶体质量较好. 相似文献
20.
Meng Wei Xiaoliang Wang Xu Pan Hongling Xiao CuiMei Wang Qifeng Hou Zhanguo Wang 《Materials Science in Semiconductor Processing》2011,14(2):97-100
We studied the influence of high temperature AlN buffer thickness on the property of GaN film on Si (1 1 1) substrate. Samples were grown by metal organic chemical vapor deposition. Optical microscopy, atomic force microscopy and X-ray diffraction were employed to characterize the samples. The results demonstrated that thickness of high temperature AlN buffer prominently influenced the morphology and the crystal quality of GaN epilayer. The optimized thickness of the AlN buffer is found to be about 150 nm. Under the optimized thickness, the largest crack-free range of GaN film is 10 mm×10 mm and the full width at half maximum of GaN (0 0 0 2) rocking curve peak is 621.7 arcsec. Using high temperature AlN/AlGaN multibuffer combined with AlN/GaN superlattices interlayer we have obtained 2 μm crack-free GaN epilayer on 2 in Si (1 1 1) substrates. 相似文献