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在蓝宝石(Al2O3)衬底上应用脉冲激光沉积技术(PLD)生长不同厚度的AlN缓冲层后进行GaN薄膜外延生长。采用高分辨X射线衍射仪(HRXRD)和扫描电子显微镜(SEM)对外延生长所得GaN薄膜的晶体质量和表面形貌进行了表征。测试结果表明:相比直接在Al2O3衬底上生长的GaN薄膜,通过生长AlN缓冲层的GaN薄膜虽然晶体质量较差,但表面较平整;而且随着AlN缓冲层厚度的增加,GaN薄膜的晶体质量和表面平整度均逐渐提高。可见,AlN缓冲层厚度对在Al2O3衬底上外延生长GaN薄膜的晶体质量和表面形貌有着重要的影响。 相似文献
3.
在蓝宝石(Al2O3)衬底上应用脉冲激光沉积技术(PLD)生长不同厚度的AlN缓冲层后进行GaN薄膜外延生长。采用高分辨X射线衍射仪(HRXRD)和扫描电子显微镜(SEM)对外延生长所得GaN薄膜的晶体质量和表面形貌进行了表征。测试结果表明: 相比直接在Al2O3衬底上生长的GaN薄膜, 通过生长AlN缓冲层的GaN薄膜虽然晶体质量较差, 但表面较平整; 而且随着AlN缓冲层厚度的增加, GaN薄膜的晶体质量和表面平整度均逐渐提高。可见, AlN缓冲层厚度对在Al2O3衬底上外延生长GaN薄膜的晶体质量和表面形貌有着重要的影响。 相似文献
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采用条形Al掩模在Si(111)衬底上进行了GaN薄膜侧向外延的研究.结果显示,当掩模条垂直于Si衬底[11-2]方向,也即GaN[10-10]方向时,GaN无法通过侧向生长合并得到表面平整的薄膜;当掩模条平行于Si衬底[11-2]方向,也即GaN[10-10]方向时,GaN侧向外延速度较快,有利于合并得到平整的薄膜.同时,研究表明,升高温度和降低生长气压都有利于侧向生长.通过优化生长工艺,在条形Al掩模Si(111)衬底上得到了连续完整的GaN薄膜.原子力显微镜测试显示,窗口区域生长的GaN薄膜位错密度约为1×109/cm2,而侧向生长的GaN薄膜位错密度降低到了5×107/cm2以下. 相似文献
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Heon Lee Masaaki Yuri Tetsuzo Ueda James S. Harris Kyusik Sin 《Journal of Electronic Materials》1997,26(8):898-902
High crystalline quality thick GaN films were grown by vapor phase epitaxy using GaCl3 and NH3. The growth rate was in the range of 10~15 Μm/h. GaN films grown at higher temperatures (960~ 1020?C) were single crystalline with smooth surface morphologies. No chlorine impurity was incorporated in these films during growth. The best crystalline quality and surface morphology of grown films was achieved by sputtering a thin A1N buffer layer, prior to growth. According to reflection high energy electron diffraction and atomic force microscopy measurements, as-sputtered A1N buffer layer was amorphous with root means square roughness of 0.395 nm and then crystallized during the GaN growth. This improved the GaN growth due to more uniform distribution of GaN nucleation. Rutherford backscattering channeling experiments produced the lowest value from the GaN film grown on a-Al2O3 with a 500å A1N buffer layer at 1020?C. 相似文献
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A. D. Hanser C. A. Wolden W. G. Perry T. Zheleva E. P. Carlson A. D. Banks R. J. Therrien R. F. Davis 《Journal of Electronic Materials》1998,27(4):238-245
The influence of diluent gas on the metalorganic vapor phase epitaxy of AlN and GaN thin films has been investigated. A computational
fluid dynamics model using the finite element method was employed to improve film uniformity and to analyze transport phenomena.
The properties of AlN and GaN thin films grown on α(6H)-SiC(0001) substrates in H2 and N2 diluent gas environments were evaluated. Thin films of AlN grown in H2 and N2 had root mean square (rms) roughness values of 1.5 and 1.8 nm, respectively. The surface and defect microstructures of the
GaN thin films, observed by scanning and transmission electron microscopy, respectively, were very similar for both diluents.
Low temperature (12K) photoluminescence measurements of GaN films grown in N2 had peak intensities and full widths at half maximum equal to or better than those films grown in H2. A room temperature Hall mobility of 275 cm2/V·s was measured on 1 μm thick, Si-doped, n-type (1×1017 cm−3) GaN films grown in N2. Acceptor-type behavior of Mg-doped GaN films deposited in N2 was repeatably obtained without post-growth annealing, in contrast to similar films grown in H2. The GaN growth rates were ∼30% higher when H2 was used as the diluent. The measured differences in the growth rates of AlN and GaN films in H2 and N2 was attributed to the different transport properties of these mixtures, and agreed well with the computer model predictions.
Nitrogen is shown to be a feasible alternative diluent to hydrogen for the growth of AlN and GaN thin films. 相似文献
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研究了采用MOCVD技术分别在100与500Torr反应室压力下生长的非故意掺杂GaN薄膜的光学与电学性能。研究表明,低压100Torr外延生长条件可以有效地降低Ga与NH3气相反应造成GaN薄膜的碳杂质沾污,从而抑制造成光致发光中黄光峰与蓝光峰的深受主的形成,所制备的材料表现出较好的光学性能。同时,不同生长压力下的GaN薄膜表现出相异的电学性能,即在500Torr下生长的样品通常表现出更高的载流子浓度((4.6-6.4)×1016 cm-3)与更高的迁移率(446-561cm2/(V.s)),而100Torr下生长的样品通常表现为更低的载流子浓度(1.56-3.99)×1016 cm-3与更低迁移率(22.9-202cm2/(V.s))。 相似文献
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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
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N. S. Zayats P. O. Gentsar V. G. Boiko O. S. Litvin M. V. Vuychik A. V. Stronski I. B. Yanchuk 《Semiconductors》2009,43(5):590-593
Morphological and optical studies of the Si-doped GaN films (doping level N Si = 1.5 × 1019 cm?3) grown by vapor-phase epitaxy from metalorganic compounds on a sapphire substrate oriented along the c axis are conducted. For the grown GaN films, the following characteristics are obtained: energy of electron transition E 0, absorption coefficient α, refractive index n, and frequencies of transverse and longitudinal optical lattice vibrations characteristic of the crystalline GaN films. 相似文献
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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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Sun Jung Kim Young Hun Seo Kee Suk Nahm Yun Bong Hahn Hyun Wook Shim Eun-Kyung Suh Kee Young Lim Hyung Jae Lee 《Journal of Electronic Materials》1999,28(8):970-974
The origin of the radiative recombination leading to yellow luminescence (YL) has been elucidated by the study of luminescence
properties of GaN films grown with two different gas feeding methods. GaN films were grown on a (0001) sapphire substrate
in a rapid thermal chemical vapor deposition (RTCVD) reactor. GaN films emitted two different luminescence energies, 2.2 and
3.47 eV, depending on the introducing position of hydrogen gas in the growth reactor. The distribution of the TMGa flow and
gas phase reactions in the reactor were investigated to understand the effect of the gas feeding methods on the optical properties
of GaN films. The results suggest that YL is related to Ga vacancies in the grown films. 相似文献
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M. A. L. Johnson Shizuo Fujita W. H. Rowland W. C. Hughes Y. W. He N. A. El-Masry J. W. Cook J. F. Schetzina J. Ren J. A. Edmond 《Journal of Electronic Materials》1996,25(5):793-797
The growth of GaN and AlGaN by molecular beam epitaxy (MBE) has been studied using GaN/SiC substrates. The GaN/SiC substrates
consisted of ∼3 μm thick GaN buffer layers grown on 6H-SiC wafers by metalorganic vapor phase epitaxy (MOVPE) at Crée Research,
Inc. The MBE-grown GaN films exhibit excellent structural and optical properties—comparable to the best GaN grown by MOVPE.
AlxGa1−xN films (x ∼ 0.06-0.08) and AlxGa1−xN/GaN multi-quantum-well structures which display good optical properties were also grown by MBE on GaN/SiC substrates. 相似文献
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Single-crystalline nonpolar GaN epitaxial films have been successfully grown on r-plane sapphire (Al2O3) substrates by pulsed laser deposition (PLD) with an in-plane epitaxial relationship of GaN[1-100]//Al2O3[11-20]. The properties of the ~500 nm-thick nonpolar GaN epitaxial films grown at temperatures ranging from 450 to 880 °C are studied in detail. It is revealed that the surface morphology, the crystalline quality, and the interfacial property of as-grown ~500 nm-thick nonpolar GaN epitaxial films are firstly improved and then decreased with the growth temperature changing from 450 to 880 °C. It shows an optimized result at the growth temperature of 850 °C, and the ~500 nm-thick nonpolar GaN epitaxial films grown at 850 °C show very smooth surface with a root-mean-square surface roughness of 5.5 nm and the best crystalline quality with the full-width at half-maximum values of X-ray rocking curves for GaN(11-20) and GaN(10-11) of 0.8° and 0.9°, respectively. Additionally, there is a 1.7 nm-thick interfacial layer existing between GaN epitaxial films and r-plane sapphire substrates. This work offers an effective approach for achieving single-crystalline nonpolar GaN epitaxial films for the fabrication of nonpolar GaN-based devices. 相似文献
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A. E. Wickenden D. D. Koleske R. L. Henry R. J. Gorman M. E. Twigg M. Fatemi J. A. Freitas Jr. W. J. Moore 《Journal of Electronic Materials》2000,29(1):21-26
Growth pressure has a dramatic influence on the grain size, transport characteristics, optical recombination processes, and
alloy composition of GaN and AlGaN films. We report on systematic studies which have been performed in a close spaced showerhead
reactor and a vertical quartz tube reactor, which demonstrate increased grain size with increased growth pressure. Data suggesting
the compensating nature of grain boundaries in GaN films is presented, and the impact of grain size on high mobility silicon-doped
GaN and highly resistive unintentionally doped GaN films is discussed. We detail the influence of pressure on AlGaN film growth,
and show how AlGaN must be grown at pressures which are lower than those used for the growth of optimized GaN films. By controlling
growth pressure, we have grown high electron mobility transistor (HEMT) device structures having highly resistive (105 Ω-cm) isolation layers, room temperature sheet carrier concentrations of 1.2×1013 cm−2 and mobilities of 1500 cm2/Vs, and reduced trapping effects in fabricated devices. 相似文献
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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
17.
Davis R.F. Roskowski A.M. Preble E.A. Speck J.S. Heying B. Freitas J.A. Jr. Glaser E.R. Carlos W.E. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2002,90(6):993-1005
Metal-organic vapor phase epitaxy (MOVPE) and molecular beam epitaxy (MBE) are the principal techniques for the growth and n-type (Si) and p-type (Mg) doping of III-nitride thin films on sapphire and silicon carbide substrates as well as previously grown GaN films. Lateral and pendeoepitaxy via MOVPE reduce significantly the dislocation density and residual strain in GaN and AlGaN films. However tilt and coalescence boundaries are produced in the laterally growing material. Very high electron mobilities in the nitrides have been realized in radio-frequency plasma-assisted MBE GaN films and in two-dimensional electron gases in the AlGaN/GaN system grown on MOVPE-derived GaN substrates at the crossover from the intermediate growth regime to the droplet regime. State-of-the-art Mg doping profiles and transport properties have been achieved in MBE-derived p-type GaN. The Mg-memory effect, and heterogeneous growth, substrate uniformity, and flux control are significant challenges for MOVPE and MBE, respectively. Photoluminescence (PL) of MOVPE-derived unintentionally doped (UID) heteroepitaxial GaN films show sharp lines near 3.478 eV due to recombination processes associated with the annihilation of free-excitons (FEs) and excitons bound to a neutral shallow donor (D/spl deg/X). 相似文献
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D. K. Gaskill A. E. Wickenden K. Doverspike B. Tadayon L. B. Rowland 《Journal of Electronic Materials》1995,24(11):1525-1530
The growth issues known to effect the quality of GaN organometallic vapor phase epitaxial films are reviewed and the best
300Kmobility vs electron concentration data are discussed. The data probably represent transport properties intrinsic to films
grown on sapphire. From the results of Hall measurements, the unintentional donor in high quality GaN films cannot be Si since
the donor ionization energy is much larger than that of films intentionally doped with Si (36 vs 26 meV). Electrical properties
of a doped channel layer are shown not to be significantly different from those of thick films which implies a viable technology
for conducting channel devices. It is argued that 77K Hall measurements are a useful indicator of GaN film quality and a compilation
of unintentionally and Si doped data is presented. The 77K data imply that, at least over a limited range, Si-doping does
not appreciably change the compensation of the GaN. The 77K data indicate that the low mobilities of films grown at low temperatures
are probably not related to dopant impurities. 相似文献
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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