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61.
ZnAl_2O_4/α-Al_2O_3衬底上GaN的生长 总被引:1,自引:0,他引:1
研究了直接在 Zn Al2 O4/α-Al2 O3 衬底上用 MOCVD法一步生长 Ga N薄膜 .利用脉冲激光淀积法在α-Al2 O3衬底上淀积了高质量 Zn O薄膜 ,对 Zn O/α-Al2 O3 样品在 110 0℃退火得到了具有 Zn Al2 O4覆盖层的 α-Al2 O3 衬底 ,并在此复合衬底上利用光加热低压 MOCVD法直接生长了纤锌矿结构 Ga N. X射线衍射谱表明反应得到的Zn Al2 O4层为 ( 111)取向 .扫描电子显微镜照片显示随退火时间从小于 3 0 min增加到 2 0 h,Zn Al2 O4表面由均匀的岛状结构衍变为突起的线状结构 ,相应的 Ga N X射线衍射谱表明 Ga N由 c轴单晶变为多晶 ,单晶 Ga N的摇摆曲线半高宽 相似文献
62.
用SiH2Cl2在3种温度下进行了多晶硅薄膜的沉积,根据膜厚计算出了沉积速率,用SEM、XRD和薄膜应力测试仪对薄膜进行测试分析.证明用SiH2Cl2在950℃时可以快速沉积用于MEMS的多晶硅. 相似文献
63.
对比研究了夹层结构N i/P t/N i分别与掺杂p型多晶硅和n型单晶硅进行快速热退火形成的硅化物薄膜的电学特性。实验结果表明,在600~800°C范围内,掺P t的N iS i薄膜电阻率低且均匀,比具有低电阻率的镍硅化物的温度范围扩大了100~150°C。依据吉布斯自由能理论,对在N i(P t)S i薄膜中掺有2%和4%的P t样品进行了分析。结果表明,掺少量的P t可以推迟N iS i向N iS i2的转化温度,提高了镍硅化物的热稳定性。最后,制作了I-V特性良好的N i(P t)S i/S i肖特基势垒二极管,更进一步证明了掺少量的P t改善了N iS i肖特基二极管的稳定性。 相似文献
64.
65.
采用传统陶瓷工艺制备了(1-x)(Bi1/2Na1/2)TiO3-xKNbO3(x=0.01,0.02,0.04,0.6,0.08,0.12)无铅压电陶瓷。利用热重-差热(TG-DSC)、X-射线衍射(XRD)和扫描电镜(SEM)等分析技术,研究了(1-x)(Bi1/2Na1/2)TiO3-xKNbO3无铅压电陶瓷的制备工艺条件对陶瓷晶体结构、压电性能的影响。TG-DSC、XRD的结果表明,该体系的的最佳预合成温度在800~850℃;SEM及性能测试的结果表明,该体系随KNbO3含量的增加,烧结温度提高,烧结的温度范围变窄,当x>0.1时,烧结的温度范围只有5~10℃。 相似文献
66.
67.
In Situ X‐Ray Diffraction Studies on Structural Changes of a P2 Layered Material during Electrochemical Desodiation/Sodiation 下载免费PDF全文
Young Hwa Jung Ane S. Christiansen Rune E. Johnsen Poul Norby Do Kyung Kim 《Advanced functional materials》2015,25(21):3227-3237
Sodium layered oxides with mixed transition metals have received significant attention as positive electrode candidates for sodium‐ion batteries because of their high reversible capacity. The phase transformations of layered compounds during electrochemical reactions are a pivotal feature for understanding the relationship between layered structures and electrochemical properties. A combination of in situ diffraction and ex situ X‐ray absorption spectroscopy reveals the phase transition mechanism for the ternary transition metal system (Fe–Mn–Co) with P2 stacking. In situ synchrotron X‐ray diffraction using a capillary‐based microbattery cell shows a structural change from P2 to O2 in P2–Na0.7Fe0.4Mn0.4Co0.2O2 at the voltage plateau above 4.1 V on desodiation. The P2 structure is restored upon subsequent sodiation. The lattice parameter c in the O2 structure decreases significantly, resulting in a volumetric contraction of the lattice toward a fully charged state. Observations on the redox behavior of each transition metal in P2–Na0.7Fe0.4Mn0.4Co0.2O2 using X‐ray absorption spectroscopy indicate that all transition metals are involved in the reduction/oxidation process. 相似文献
68.
Cadmium selenide films were synthesized using simple electrodeposition method on indium tin oxide coated glass substrates. The synthesized films were post annealed at 200 °C, 300 °C and 400 °C. X-ray diffraction of the films showed the hexagonal structure with crystallite size <3 nm for as deposited films and 3–25 nm for annealed films. The surface morphology of films using field emission scanning electron microscopy showed granular surface. The high resolution transmission electron microscopy of a crystallite of the film revealed lattice fringes which measured lattice spacing of 3.13 Å corresponding to (002) plane, indicating the lattice contraction effect, due to small size of CdSe nanocrystallite. The calculation of optical band gap using UV–visible absorption spectrum showed strong red-shift with increase in crystallite size, indicating to the charge confinement in CdSe nanocrystallite. 相似文献
69.
Ke Meng Xiao Wang Qiaofei Xu Zhimin Li Zhou Liu Longlong Wu Youdi Hu Ning Liu Gang Chen 《Advanced functional materials》2019,29(35)
Metal halide perovskites have revolutionized the development of highly efficient, solution‐processable solar cells. Further advancements rely on improving perovskite film qualities through a better understanding of the underlying growth mechanism. Here, a systematic in situ grazing‐incidence X‐ray diffraction investigation is performed, facilitated by other techniques, on the sequential deposition of formamidinium lead iodide (FAPbI3)‐based perovskite films. The active chemical reaction, composition distribution, phase transition, and crystal grain orientation are all visualized following the entire perovskite formation process. Furthermore, the influences of additive ions on the crystallization speed, grain orientation, and morphology of FAPbI3‐based films, along with their photovoltaic performances, are fully evaluated and optimized, which leads to highly reproducible and efficient perovskite solar cells. The findings provide key insights into the perovskite growth mechanism and suggest the fabrication of high‐quality perovskite films for widespread optoelectronic applications. 相似文献
70.
P. Rozenak 《Journal of Electronic Materials》1997,26(7):868-872
Silicon strained epitaxial films were grown on Si (001) substrates by low energy ion beam assisted molecular beam epitaxy.
Films grown in the range of 450– 550°C with concurrent Ar+ ion bombardment (100 eV) were characterized using x-ray diffraction and transmission electron microscopy and found to be
disloca-tion free and ununiformly strained. During aging, the strained layers stay stable until 500°C. Relaxation of most
of the strain occurred at temperatures of 500-650°C. At higher aging temperatures, the strained layers relaxed by the formation
of dense dislocation structures. 相似文献