有机源载气对MOCVD生长InGaN薄膜的影响研究

彩MOCVD技术以Al2O3为衬底在GaN膜上生长了InxGa1-xN薄膜。以卢瑟福背散射／沟道技术和光致发光技术对InxGa1-xN/GaN/Al2O3样品进行了测试。获得了合金层的组分，厚度，结晶品质及发光性能等信息。研究表明：在以N2作主载气的情况下，有机源的载气对InxGa1-xN膜的In组分和生长速率影响很大，生长温度为760℃时，以70ml/min的N2作有机源载气得到的InxGa1-xN膜的In组分为0．10，生长速率为6．0nm/min,而以70ml/min的H2作有机源载气得到的InxGa1-xN薄膜的In组分为0．06，生长速率为10．6nm/min.本文首次报导了载气中含有少量H2能增大InxGa1-xN薄膜的生长速率的现象。     

金属有机化学汽相沉积生长InGaN薄膜的研究

以Al2O3为衬底,采用金属有机汽相沉积（MOCVD）技术在GaN膜上生长了InxGa1-xN薄膜。以卢瑟福背散射／沟道技术和光致发光技术对InxGa1-xN／GaN/Al2O3样品进行了分析,研究表明,金属有机汽相沉积生长高In组分InxGa1-xN薄膜有一最佳TMIn/TEGa摩尔流量比。在一定范围内,降低其摩尔流量比,合金的生长速率增高,In组分提高;进一步降低TMIn/TEGa摩尔流量比,导致In组分下降,研究还表明,InGan薄膜的结晶品质随In组分的增大而下降,InGan薄膜的In组分由0．04增大到0．10,其最低沟道产额比由4．1％增至11．0％。     

MOCVD生长的GaN单晶膜透射光谱研究

采用MOCVD技术在Al2O3(0001)衬底上生长了GaN薄膜，使用透射光谱、光致发光光谱和X射线双晶衍射三种技术测试了五类GaN薄膜样品，实验结果表明：GaN薄膜透射谱反映出的GaN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；而X射线双晶衍射峰半高宽最小的样品，其PL谱的带边峰却很弱，这说明PL谱反映样品的光学性能与X射线双晶衍射获得的结晶质量不存在简单的对应关系，同时还报导了一种特殊工艺生长的高阻GaN样品的RBS／沟道结果。     

应力和掺杂对Mg:GaN薄膜光致发光光谱影响的研究

对化学气相沉积(MOCVD)法在宝石衬底上生长的Mg掺杂GaN薄膜的表面及其GaN缓冲层的光致发光(PL)光谱进行了测量，用Raman光谱和x射线衍射(XRD)对GaN薄膜中的应力进行确定，通过PL光谱中的中性束缚激子跃迁能量的变化确定薄膜中应力的影响，从而研究Mg掺杂对p型GaN的DAP跃迁影响规律. 关键词： 光致发光 应力 Raman光谱     

分子束外延HgCdTe材料的光致发光研究

报道了分子束外延生长 Ｈｇ０．６８ Ｃｄ０．３２ Ｔｅ 材料的光致发光测量结果。研究了原生样品和退火处理样品、以及氮离子注入样品的低温光致发光特征。对光致发光的测试结果进行拟合得到的禁带宽度, 与用红外透射谱得到的薄膜禁带宽相近; 其半峰宽和带尾能量较小, 显示了较高的薄膜质量。样品经过退火后带尾能量降低, 双晶衍射的半峰宽也有明显的变窄     

火焰喷雾法合成ZnO和MgxZn1－xO纳米颗粒的光学性能研究

利用火焰喷雾法成功制备了纳米级的ZnO和Mg_xZn_1-xO颗粒. 通过对样品的X射线衍射谱和场发射扫描电子显微镜照片分析，发现制备的颗粒大小较为均匀，直径在20nm左右；镁元素的掺入引起晶格常数变小. 通过透射光谱和光致发光谱的测量，发现Mg_xZn_1-xO颗粒的禁带宽度远大于ZnO颗粒的禁带宽度，同时对两组样品的紫外发光和可见发光的强度变化和发光机理进行了探讨. 关键词： 火焰喷雾 ZnO 禁带宽度 纳米颗粒     

Er2O3薄膜的光学常数和介电性能

采用射频磁控反应溅射技术,在不同的Ar/O2流量比条件下制备了系列Er2O3薄膜样品.采用椭偏光谱和紫外一可见光透射光谱测试分析技术,研究了Er2O3薄膜的折射率、消光系数、透射率和光学带隙等光学常数与制备工艺的关系.研究了不同条件下制备的Er2O3薄膜的介电常数和Ⅰ～Ⅴ特性.结果表明,Er2O3薄膜的折射率、禁带宽度和介电常数随Ar/O2流鼍比的增加而增加,而消光系数基本不随Ar:O2流量比的变化而变化.在Ar:O2流量比为7:1制备的Er2O3薄膜具有较好的物理性能,在可见红外波段其折射率约1.81,消光系数为3.7×10-6,禁带宽度5.73 eV,介电常数为10.5.     

MgxZn1-xO单晶薄膜的结构和光学性质

用等离子辅助分子束外延(P-MBE)的方法,在蓝宝石c平面上外延生长了MgxZn1-xO合金薄膜。在0≤x≤0．2范围内薄膜保持着ZnO的纤锌矿结构不变。X射线双晶衍射谱的结果表明生长的样品是单晶薄膜。据布喇格衍射公式计算得到,随着Mg含量的增加,薄膜的品格常数C由0．5205nm减小到0．5185nm。室温光致发光谱出现很强的紫外近带发射(NBE)峰,没有观察到深能级(DL)发射,且随着Mg的掺入量的增加,紫外发射峰有明显的蓝移。透射光谱的结果表明,合金薄膜的吸收边随着Mg离子的掺入逐渐向高能侧移动,这与室温下光致发光的结果是相吻合的,并计算出随着x值增加,带隙宽度从3．338eV逐渐展宽到3．682eV。通过研究Mg0.12Zn0.88O样品的变温光谱,将紫外发射归结为束缚在施主能级上的束缚激子发射。并详细地研究了在整个温度变化过程中,束缚激子的两个不同的猝灭过程以及谱线的半峰全宽与温度变化的关系。     

火焰喷雾法合成ZnO和MgxZn1-xO纳米颗粒的光学性能研究

利用火焰喷雾法成功制备了纳米级的ZnO和Mgxzn1-xO颗粒.通过对样品的X射线衍射谱和场发射扫描电子显微镜照片分析,发现制备的颗粒大小较为均匀,直径在20 nm左右;镁元素的掺入引起晶格常数变小.通过透射光谱和光致发光谱的测量,发现MgxZn1-xO颗粒的禁带宽度远大于ZnO颗粒的禁带宽度,同时对两组样品的紫外发光和可见发光的强度变化和发光机理进行了探讨.     

ZnO薄膜的反射、透射光谱及能带结构测量

采用正入射的方法研究了生长在硅基片上的氧化锌薄膜的反射光谱，测量出氧化锌薄膜的光学吸收边在370nm，所对应的能量值为3.35eV，测量生长在石英玻璃基片上的氧化锌薄膜的透射光谱，得到相同的吸收边，表明ZnO薄膜的光学禁带宽度与体材料的禁带宽度一致，反射谱中，在550－600nm之间观察到一个吸收峰，吸收峰的位置以及吸收边的陡峭程度都薄膜的结晶状况的不同而有所不同。     

GaN1-xPx三元合金的光学与结构特性

对采用金属有机化学气相淀积(MOCVD)技术生长的GaN1-xPx三元合金进行了低温光致发光(PL)和X射线衍射(XRD)测试分析,与来自GaN层的带边发射相比,P的摩尔分数比为0．03,0．11和0．15的GaN1-xPx的光致发光峰分别呈现出了73meV,78meV和100meV的红移,文中将这种红移归因于GaN1-xPx合金具有大的带隙能量弯曲系数。X射线衍射结果表明GaN1-xPx三元合金仍为六方结构晶体,且随着P组份比的增加,GaN1-xPx合金的(0002)衍射峰逐渐向小角度方向移动,即晶格常量变大,同时,(0002)衍射峰谱线不断宽化,说明由于替位式P原子的不规则分布以及部分间隙P原子的影响造成了GaN1-xPx样品的晶格畸变。在GaN1-xPx的光致发光谱及X射线衍射谱中均未观测到相应的有关GaP的峰,表明所生长的高P含量的GaN1-xPx三元合金没有产生明显的相分离。     

Structural characterization of epitaxial Cr(x)Mo(1-x) alloy thin films

To develop a model system containing regularly spaced misfit dislocations for studies of the radiation resistance of nanoscale defects, epitaxial thin films of Cr, Mo, and Cr(x)Mo(1-x) alloys were deposited on MgO(001) by molecular beam epitaxy. Film compositions were chosen to vary the lattice mismatch with MgO. The film structure was investigated by x-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS) and scanning transmission electron microscopy (STEM). Epitaxial films with reasonably high crystalline quality and abrupt interfaces were achieved at a relatively low deposition temperature, as confirmed by STEM. However, it was found by XRD and RBS in the channeling geometry that increasing the Mo content of the CrMo alloy films degraded the crystalline quality, despite the improved lattice match with MgO. XRD rocking curve data indicated that regions of different crystalline order may be present within the films with higher Mo content. This is tentatively ascribed to spinodal decomposition into Cr-rich and Mo-rich regions, as predicted by the Cr(x)Mo(1-x) phase diagram.     

Structural and optical properties of Al1-xInxN epilayers on GaN template grown by metalorganic chemical vapor deposition

This paper reports that Al1 xInxN epilayers were grown on GaN template by metalorganic chemical vapor de-position with an In content of 7%-20%. X-ray diffraction results indicate that all these Al1 xInxN epilayers have a relatively low density of threading dislocations. Rutherford backscattering/channeling measurements provide the exact compositional information and show that a gradual variation in composition of the Al1 xInxN epilayer happens along the growth direction. The experimental results of optical reflection clearly show the bandgap energies of Al1 xInxN epilayers. A bowing parameter of 6.5 eV is obtained from the compositional dependence of the energy gap. The cathodoluminescence peak energy of the Al1 xInxN epilayer is much lower than its bandgap, indicating a relatively large Stokes shift in the Al1 xInxN sample.     

显微拉曼研究外延生长的BaTiO_(3-x)薄膜的结构相变与结构动力学(英文)

我们用显微拉曼、卢瑟福背散射谱、X射线散射和非对称摇摆等实验手段研究了在1 0 - 2 到1 0 - 5帕氧气压下用激光分子束外延技术生长的BaTiO3-x薄膜的结构动力学特性。测量结果表明生长氧压越低,晶格常数c和c/a越大,晶格常数a稍微减小,晶胞体积变大。随着生长氧压的减小,薄膜中氧含量减小。在3 0×1 0 - 5帕氧气压下生长的薄膜中氧缺陷可达0 48,但是样品的四方相结构可以很好的维持。显微拉曼研究进一步确定了样品都是四方相结构。另外,在BaTiO2 52 薄膜的拉曼光谱中发现高频段有两个新峰,其可能是由于氧缺陷导致的二级拉曼散射引起的。随着生长氧压的减小,拉曼峰向低频移动,表明薄膜中的应力减小。同时,拉曼峰变宽,这可能是由于氧缺陷导致的结构畸变引起的。由于在薄膜中存在二维张应力,BaTiO3单晶样品中的结构相变特征在我们的样品中从78到5 5 0K的温度范围内不存在。     

Ion-channeling analysis for epitaxial YBa2Cu3Ox superconducting thin films by laser deposition

Rutherford backscattering/channeling has been applied to study structures of as-deposited epitaxial YBa₂Cu₃O_x thin films prepared on {100}SrTiO₃ by laser deposition. The epitaxial growth has been proved by a planar channeling experiment and transmission electron microscopy. An axial angular yield profile for barium along the c-axis has ideal characters of compensating shoulders and of a flat region at the bottom of the channeling dip. The thermal vibration amplitude, which has been determined from a half-angle of the axial angular yield profile by using Gemmell's channeling model for polyatomic crystals, is compared to those from diffraction experiments.     

Features of the pulsed treatment of silicon layers implanted with erbium ions

The formation of thin-film solid solutions of erbium in silicon and synthesis of erbium silicides were performed using continuous implantation of silicon with erbium ions followed by pulsed ion-beam treatment. Structural and optical properties of formed Si:Er layers were studied by Rutherford backscattering, transmission electron microscopy, and low-temperature photoluminescence. The dependences of erbium redistribution, the microstructure of Si:Er layers, and their photoluminescence in the near-IR region on the erbium concentration and pulsed treatment conditions were determined.     

ZnO nanoparticle creating in a SiO2/Si structure using the Zn ion implantation with subsequent heat treatment

The distribution profiles of the dopant in the surface layer of a SiO₂/Si structure implanted with Zn and O ions are studied via Rutherford backscattering spectroscopy for He²⁺ ions using the channeling technique. The redistribution of implanted impurities in the Si surface layer during the formation process of zinc oxide (ZnO) nanoparticles is analyzed. The effect of the annealing temperature on the formation process and growth of ZnO nanoparticles is studied. The sample-surface morphology is examined via atomic force microscopy. The optical absorption and photoluminescence of the implanted layers are studied.     

白宝石衬底上生长的MgxZn1-xO晶体薄膜的结构和光学性能

在白宝石 (sapphire)衬底上低温外延生长出了MgxZn1 -xO晶体薄膜 .x射线衍射 (XRD)及能量色散x射线 (EDX)分析表明 ,MgxZn1 -xO薄膜的晶体结构依赖于薄膜中Mg的组分x,随着Mg组分的增大 ,MgxZn1 -xO薄膜的结构从与ZnO晶体一致的六方结构转变为与MgO晶体一致的立方结构 .对MgxZn1 -xO薄膜的紫外透射光谱及紫外光致荧光谱 (UVPL)的分析表明 ,随着Mg组分的增大 ,光学吸收边产生明显的蓝移 ,表明MgxZn1 -xO晶体薄膜的带隙增大 ,且带隙连续可调 .吸收光谱和XRD测量显示 ,带隙高达 5 6 5eV的MgxZn1 -xO晶体薄膜与MgO之间的晶格失配仅为0 16 % .     

Photoluminescence of SiO<Subscript>2</Subscript> layers prepared on β-SiC films and an analysis of their elemental composition

The spectra of pulsed time-resolved photoluminescence of oxidized films prepared through electrochemical oxidation on SiC/Si films are investigated. The elemental composition of the films is analyzed using Rutherford backscattering and nuclear reactions. It is revealed that a certain part of the carbon atoms remain in the oxide. The specific features of the parameters of the spectral bands and their kinetics with time are explained by the presence of carbon uniformly distributed throughout the oxide. The structure of oxides at different oxidation times is examined with the use of electron microscopy. Conclusions are drawn regarding possible photoluminescence centers.     

Low-temperature growth of epitaxial ZnO films on (001) sapphire by ultraviolet- assisted pulsed laser deposition

ZnO thin films have been grown on thin Si₃N₄ membranes and (001) sapphire substrates by an ultraviolet-assisted pulsed laser deposition (UVPLD) technique. The microstructure of the films grown on Si₃N₄ membranes, investigated by transmission electron microscopy, showed that crystalline and textured films can be grown by UVPLD at a substrate temperature of only 100 °C. For deposition temperatures higher than 400 °C, ZnO films grown on sapphire substrates were found to be epitaxial by Rutherford backscattering (RBS) and X-ray diffraction measurements. The minimum yield of channeling RBS spectra recorded from films deposited at 550 °C was around 2% and the FWHM of the rocking curve for the (002) diffraction peak was 0.17°; these values are similar to those recorded from ZnO layers grown by conventional PLD at 750 °C.