共查询到20条相似文献,搜索用时 15 毫秒
1.
Zhizhong Chen Jianming Zhu Bo Shen Rong Zhang Yugang Zhou Peng Chen Weiping Li Wenjun Liu Zhenlin Wang Youdou Zheng Shusheng Jiang 《Materials & Design》2000,21(6):579-582
Transmission electron microscopy (TEM), double crystal X-ray diffraction (XRD), photoluminescence (PL) and Raman scattering measurement were applied to study the correlation between the microstructure and material properties of the GaN films grown by light radiation heating metalorganic chemical vapor deposition (LRH-MOCVD), using GaN buffer layer on sapphire substrates. Corresponding to the density of the threading dislocation (TD) increasing approximately one order, the yellow luminescence (YL) intensity was strengthened from negligible to two orders higher than the band-edge emission intensity. The full width of half maximum (FWHM) of GaN (0002) peak of the XRD rocking curve was widened from 11 to 15 min, and in Raman spectra, the width of E2 mode is broadened from 5 cm−1 to 7 cm−1. A ‘zippers’ structure of GaN buffer layer was discovered by high-resolution electron microscope (HREM). 相似文献
2.
3.
Aluminum nitride (AlN) films were grown on sapphire substrates by radio frequency (RF) magnetron sputtering in plasma containing a mixture of argon and nitrogen, using a pure aluminum target. The effect of RF power was investigated with respect to growth rate, surface roughness, and transmittance of AlN films. As the RF power increases, the growth rate increases and the root mean square of surface roughness decreases while the absorption edge shifts to longer wavelength. This shift is believed to be due to the defects induced by ion bombardment. 相似文献
4.
5.
A ‘hot wall epitaxy’ is applied to grow PbTe thin films on sapphire substrates with BaF2 buffer layer deposited by molecular beam epitaxy (MBE). The microstructural and strain state characteristics of PbTe layer were examined with high resolution X-ray diffraction techniques. The epilayer is composed of two (111)PbTe‖(0001)Al2O3 epitaxially oriented domain variants. The domains are azimuthally rotated and their interfacial directions relative to the substrate are [011?]PbTe‖Al2O3 and [1?54?]PbTe‖Al2O3, respectively. Another possible alignment of the domain variant corresponds to PbTe‖Al2O3 orientation. The strain state analysis of PbTe layer points to its relaxation via domain formation and high dislocation density generation in the lattice. Despite the domains formation the measured mobility of electron carriers is approximately 1600 cm2/V s and 30 000 cm2/V s at 300 K and 77 K, respectively. The theoretical analysis of the measured electrical properties indicates that the scattering by acoustic and optical phonons is the factor affecting the conduction process. 相似文献
6.
R.V. Aldridge 《Thin solid films》1979,60(3):321-333
We report measurements of the temperature variation of the Hall effect, magnetoresistance and resistivity of thin films of nickel deposited onto optically flat sapphire substrates at 4 K. The as-deposited films showed almost square hysteresis loops for the Hall voltage as a function of the applied field. The loops disappeared as the films were annealed to 500 K, the Hall voltage reverting to the normal shape expected for a thin ferromagnetic film orthogonal to an external magnetic field. The annealed films 4–20 nm thick gave magnetization values at high temperatures that were close to those expected for bulk nickel. 相似文献
7.
8.
Tarala V. A. Altakhov A. S. Ambartsumov M. G. Martens V. Ya. 《Technical Physics Letters》2017,43(1):74-77
Technical Physics Letters - The possibility of growing oriented AlN films on Al2O3 substrates at temperatures below 300°C by plasma-enhanced atomic layer deposition was examined. The samples... 相似文献
9.
10.
NiAlFe thin films were prepared onto sapphire single crystals by physical vapour deposition (PVD) and these were analysed by X-ray photoelectron spectroscopy (XPS) in combination with argon ion etching to determine the composition depth profile and interfacial characteristics of the samples. Non-linear least square fitting (NLLSF) analysis of the data was required due to the conflict of several peaks of interest. XPS depth profiles show that, for non-annealed NiAlFe–Al2O3, the interface is sharp and oxygen diffusion occurs at different annealing temperatures. Ni remains chemically unaffected by the presence of oxygen while the formation of aluminium oxide compounds occur. Two iron species are present in the film thickness where the low binding energy component is attributed to Fe–Fe or Fe–Al interactions and the higher one to the NiAlFe compound. The reduction-dissolution of the sapphire substrate leads to depletion of oxygen in the sapphire surface layer and the formation of alumina at the NiAlFe–Al2O3 interface. Within the film, aluminium and nickel are present as an intermetallic compound. Annealing of the samples induces surface oxidation and the subsequent formation of an Al2O3 layer. This type of interphase morphology should lead to optimal fibre/matrix (F–M) adhesion, and therefore optimal load transfer between the matrix and reinforcement. 相似文献
11.
用电子束蒸发氧化铪靶的方法.在SOI(绝缘体上硅)材料上制备了氧化铪薄膜,随后在氮气中进行快速退火(600℃.300s)。借助掠角X射线衍射(GAXRD)、X射线光电子能谱(XPS)、高分辨透射电镜(HRTEM)技术分析了样品的微观结构.研究了样品在退火前后发生的组成及结构变化.结果表明退火后氧化铪薄膜由退火前的非晶态转变为单斜结构的多晶态,薄膜中的O/Hf原子比较退火前更接近化学计量比2。借助扩展电阻探针(SRP)技术考察了退火前后薄膜的电学性能.证明在SOI材料上制备的多晶氧化铪薄膜同样具有较好的电介质绝缘性能。 相似文献
12.
《Thin solid films》1987,148(3):233-241
The temperature dependence of the electrical conduction in discontinuous silver films on sapphire substrates was examined in the temperature range 120–300 K. The experimental dependences were approximated by functions taken from some theoretical models. The best approximation was found using the phenomenological model presented previously by the present author. 相似文献
13.
Cheng-Liang Wang Jyh-Rong Gong 《Journal of Materials Science: Materials in Electronics》2005,16(2):107-110
Low-temperature (LT) AlxGa1–xN (0.1 < x < 0.8) films, 0.4 m in thickness, were prepared on (0001) sapphire substrates at 500,C by alternate supply of Ga and Al alkyls and ammonia (NH3). Al composition in the solid phase was identified based on the shift of the (0002) Bragg angle of X-ray diffraction. A series of high temperature (HT) GaN films, 1.0 m in thickness, were also grown at 1000,C on the LT-AlxGa1–xN coated (0001) sapphire substrates with buffer layer thickness ranging from 7.5 to 20 nm. It was found that the optimized LT-AlxGa1–xN buffer layer thickness decreases linearly with the Al-content. As-grown HT-GaN films having LT-LT-Al0.43Ga0.57N buffer layers show smooth surface based on optical microscopic (OM) observations. Transmission electron microscopy (TEM) confirms the mono-crystalline nature of the HT-GaN films. The quenched near band-edge photoluminescence (PL) emissions and an apparent yellow luminescence of the HT-GaN films are attributed to the LT-AlxGa1–xN buffer layer induced mosaic microstructure and bonding defects in the films. 相似文献
14.
M. I. Kotelyanskii I. M. Kotelyanskii V. B. Kravchenko 《Technical Physics Letters》2000,26(2):163-164
It is suggested to deposit III–V nitride films onto sapphire substrates upon preliminary deposition of a buffer sublayer of
a crystalline material with a cubic structure. It is shown experimentally that the deposition of a heteroepitaxial niobium
sublayer onto a (0001)-oriented sapphire substrate or a niobium nitride sublayer onto a (
11[`2]011\bar 20
)-oriented Al2O3 substrate eliminates a 30° rotation of the (0001)-oriented nitride film in the substrate plane. The elimination of this rotation
provides considerable reduction of the lattice mismatch between the substrate and the nitride film, which, in turn, should
increase the degree of crystal perfection of the film. In addition, the planes of semiconductor nitride films become parallel
to the natural cleavage planes of the substrate. This fact provides for the possibility of manufacturing a heterolaser with
a Fabry-Perot resonator, in which the role of the mirrors is played by natural cleavage planes of the film. 相似文献
15.
16.
The hydrothermal synthesis of ZnAPO-34 films supported on alumina substrates was reported in this paper. Synthesis parameters of the films were extensively examined. Organic content, water content, alumina source, and supports played important roles in the syntheses of ZnAPO-34 films. The best synthesis composition was found to be 0.4ZnO : 0.8Al2O3 : 1P2O5 : 2TEAOH : 225–550H2O with aluminum isopropoxide as alumina source. However, repeated syntheses were necessary to synthesize contineous ZnAPO-34 films on both nonporous an porous alumina supports. 相似文献
17.
Wenliang Wang Weijia Yang Zuolian Liu Yunhao Lin Shizhong Zhou Huiromg Qian Fangliang Gao Lei Wen Shugang Zhang Guoqiang Li 《Journal of Materials Science》2014,49(9):3511-3518
The 2-inch-diameter homogeneous GaN films have been epitaxially grown on sapphire substrates by pulsed laser deposition (PLD) technique with optimized laser rastering and PLD growth conditions. The as-grown GaN films are characterized by in situ reflection high-energy electron diffraction, white-light interferometry, scanning electron microscopy, atomic force microscopy (AFM), grazing incidence angle X-ray reflectivity, reciprocal space mappings, and micro-Raman spectroscopy for surface morphologies and structural properties. The as-grown 2-inch-diameter single-crystalline GaN films exhibit excellent thickness uniformity with a root-mean-square (RMS) inhomogeneity less than 3.4 % and very smooth surface with a RMS roughness less than 1.3 nm measured by AFM. There is a maximum of 1.2 nm thick interfacial layer existing between the as-grown GaN films and sapphire substrates, and the as-grown 310 nm thick GaN films are almost fully relaxed only with an in-plane compressive strain of 0.044 %. This work demonstrates a possibility for achieving high-quality large-scale GaN films with uniform thickness and atomically abrupt interface by PLD, and is of great interest for the commercial development of GaN-based optoelectronic devices. 相似文献
18.
Lanthanum modified lead zirconate titanate (PLZT) thin films were fabricated on sapphire (0001) substrate by sol-gel method. The cell parameters of films were calculated with help of whole-pattern fitting procedure. The evolution of strain, shift of absorption edge and change in the band tailing with film thickness were found and analyzed for amorphous and polycrystalline PLZT films. The refractive index n was computed with help of “Envelope method” and dielectric function was calculated by fitting the measured optical transmission spectrum. 相似文献
19.
C面蓝宝石衬底上6H-SiC薄膜的低压化学气相外延生长与表征 总被引:1,自引:0,他引:1
采用低压化学气相沉积方法在C面蓝宝石衬底上异质外延生长出高结晶质量和良好表面形貌的6H-SiC薄膜,研究了CsHs气体流速对薄膜结晶质量的影响.随着C3Hs气体流速的降低,薄膜的结晶质量先增加后降低,表明薄膜的生长在开始阶段受表面反应控制,而后受质量输运控制.所得到的结晶质量最好的6H-SiC薄膜,其摇摆曲线半高宽为0.6°,已经达到单晶水平.没有使用A1N过渡层,制备出结晶质量更好的SiC薄膜,表明对于蓝宝石衬底上SiC薄膜的生长,起决定性因素的是温度,过渡层不是影响SiC薄膜结晶质量的主要因素. 相似文献
20.
J. H EDGAR C. H WEI D. T SMITH T. J KISTENMACHER W. A BRYDEN 《Journal of Materials Science: Materials in Electronics》1997,8(5):307-312
The structural properties of epitaxial indium nitride thin films were characterized and related to the mechanical properties
as measured by nanoindentation. The seven epitaxial InN films examined were deposited over the temperature range 200–400°C
by reactive magnetron sputtering on (0 0.1) sapphire substrates buffered with a thin AlN layer. The hardness, surface texture
and crystal quality of the InN films were functions of the deposition temperature, with the maximum hardness (11.2 GPa), the
smoothest surface, the minimum c-lattice constant (0.5708 nm), and the minimum (0 0.4) X-ray rocking curve width (0.6°) all
occurring at the deposition temperature of 350°C. The crystal quality and the hardness of the InN films degraded at both higher
and lower temperatures.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献