Effects of rapid thermal annealing on the morphology and optical properity of ultrathin InSb film deposited on SiO2/Si substrate

Ultrathin InSb thin films on SiO₂/Si substrates are prepared by radio frequency (RF) magnetron sputtering and rapid thermal annealing (RTA) at 300, 400, and 500℃, respectively. X-ray diffraction (XRD) indicates that InSb film treated by RTA at 500℃, which is higher than its melting temperature (about 485℃), shows a monocrystalline-like feature. High-resolution transmission electron microscopy (HRTEM) micrograph shows that melt recrystallization of InSb film on SiO₂/Si(111) substrate is along the (111) planes. The transmittances of InSb films decrease and the optical band gaps redshift from 0.24 eV to 0.19 eV with annealing temperature increasing from 300℃ to 500℃, which is indicated by Fourier transform infrared spectroscopy (FTIR) measurement. The observed changes demonstrate that RAT is a viable technique for improving characteristics of InSb films, especially the melt-recrystallized film treated by RTA at 500℃.     

Transport properties of InSb nanowire arrays

Single-crystalline InSb nanowire arrays were prepared by pulsed electrochemical deposition into anodic alumina membranes, and subjected to characterization using X-ray diffraction, field emission scanning electron microscope and transmission electron microscopy. A nonlinear I–V characteristic and a decreased resistance with temperature were observed in InSb nanowire arrays. The mechanisms of the different temperature dependencies of the resistance of InSb nanowires with different diameters were discussed. PACS 67.55.Hc; 73.63.Bd; 61.82.Fk     

A Study on the Components of MgB2 Thick Film Preparedvia HPCVD

Superconducting MgB₂ thick film has been prepared via hybrid physical-chemical vapor deposition method on Al₂O₃ (0001) substrate by using B₂H₆ and magnesium ingot as raw materials reacted from 730 to 830°C for 40 min under 20 to 30 kPa. Its thickness is about 40 μm. The MgB₂ thick film shows T _c (onset) = 39.0 K and T _c (0) = 37.2 K. X-ray diffraction pattern shows that the film grown along (101) direction has small amount of impurities of Mg and MgO. Scanning electron microscopy and energy dispersive X-ray spectroscopy indicated that these impurities existed indeed and were Mg rich. The MgO film was formed on the surface of the MgB₂ thick film to further protect the sample from oxidation. We presented a new mechanism for the formation of the thick film. Translated from Chinese Journal of Low Temperature Physics, 2005, 27(1) (in Chinese)     

Effects of In and Sb mono-layers to form rotated InSb films on a Si(1 1 1) substrate

A new method for InSb heteroepitaxial growth on a Si substrate was introduced in our previous work, in which an InSb film was formed via an InSb bi-layer. In the present work, to study the effects of In and Sb individual layers on the InSb film quality, InSb was deposited onto an InSb bi-layer, In mono-layer, and Sb mono-layer on a Si substrate. It was found that both In and Sb layers (in other words, InSb bi-layer) were essential to form a fine InSb film.     

Classical in-plane negative magnetoresistance and quantum positive magnetoresistance in undoped InSb thin films on GaAs (1 0 0) substrates

Magnetoresistance (MR) effects have been investigated in perpendicular and parallel magnetic fields at 300, 80 K and liquid He temperatures for undoped InSb thin films 0.1–2.3 μm thick grown on GaAs(1 0 0) substrates by MBE. At high temperatures, the intrinsic carriers show the parabolic negative MR observable only in magnetic fields parallel to the film. The skipping-orbit effect due to surface boundary scattering in the classical orbits in the plane vertical to the film has been argued to be responsible for the negative MR. At low temperatures (T=80 K), the transport is dominated by the two-dimensional (2D) electrons in the accumulation layers at the InSb/GaAs(1 0 0) hetero interface; MR is positive and shows a logarithmic increase with anisotropy between parallel and perpendicular field orientation, arising from the 2D weak anti-localization (WAL) that reflects the interplay between the spin-Zeeman effect and strong spin–orbit interaction caused by the asymmetric potential at the interface (Rashba term). The zero-field spin splitting energy of Δ₀13 meV, the electron effective mass of m^*0.10m₀ seven times of the band edge mass in bulk InSb and the effective g-factor of |g^*|15 in the accumulation layer have been inferred from fits of MR for the 0.1 μm thick film to the 2D WL theory.     

Preparation and characterization of alkyl sulfate and alkylbenzene sulfonate surfactants/TiO2 hybrid thin films by the liquid phase deposition (LPD) method

Hybrid titanium oxide thin films containing surfactants, sodium dodecyl benzylsulfonate and sodium dodecyl sulfate, have been prepared by a novel liquid-phase deposition method. It is a new attempt to prepare organic–inorganic hybrid thin film by this method which usually be applied in preparing metal oxide thin film before. The two kinds of surfactants/TiO₂ hybrid thin films were characterized by means of FT-IR, SEM, XRD, fluorescence X-ray, ICP–AES and Raman spectroscopy, and showed noticeable differences in surface top view and particle diameter, cross-section image and thickness, deposited amount of Ti, XRD patterns and Raman shift. The reasons giving rise to above differences of the two kinds composite thin films has been discussed. The deposition mechanism of organic–inorganic hybrid thin film has been also presumed. The use of this processing parameter may open up a new way to the preparing of the organic–inorganic hybrid thin film.     

Preparation of Co<Subscript>3</Subscript>O<Subscript>4</Subscript> hollow microsphere/graphene/carbon nanotube flexible film as a binder-free anode material for lithium-ion batteries

A flexible Co₃O₄ hollow microsphere/graphene/carbon nanotube hybrid film is successfully prepared through a facile filtration strategy and a subsequent thermally treated process. The composition, morphology, and structure of the as-prepared film are characterized by X-ray diffraction, X-ray photoelectron spectrometer, scanning electron microscopy, and transmission electron microscopy. Based on the morphology characterizations on the hybrid film, the Co₃O₄ hollow microspheres are uniformly and closely attached on three-dimensional (3D) graphene/carbon nanotubes (GR/CNTs) network, which decreases the agglomeration of Co₃O₄ microspheres effectively. In this hybrid film, the 3D GR/CNT network which enhances conductance as well as prevents aggregation is a benefit to help Co₃O₄ to exert its lithium storage capabilities sufficiently. When used as a binder-free anode material for lithium-ion batteries, the hybrid film delivers excellent electrochemical properties involving reversible capacity (863 mAh g^?1 at a current density of 100 mA g^?1) and rate performance (185 mAh g^?1 at a current density of 1600 mA g^?1).     

Molecular crystallization of rubrene thin films assisted by gold nanoparticles

We demonstrate that crystalline organic rubrene thin films can be obtained by a facile spin-coating method using gold (Au) nanoparticles (NPs). Dodecanethiol-functionalized Au NPs were dissolved with rubrene molecules in solvent and a thin film of Au/rubrene was prepared by a simple spin coating process. The results of confocal photoluminescence (PL) and absorption spectral mapping confirmed the local formation of orthorhombic crystalline structures of the Au/rubrene hybrid film, in contrast to the monoclinic structure of plain rubrene films. Further, the results of transmission electron microscopy (TEM) and X-ray diffraction analysis, as well as Raman spectroscopy measurements of the rubrene and Au/rubrene films suggested the formation of high crystalline Au/rubrene film. The molecular crystallization of the Au/rubrene hybrid film is attributed to the nucleation effect of the Au NPs.     

Negative photoconductance in thin indium antimonide films

Negative photoconductance or optical quenching has been observed in thin InSb films, fabricated by vacuum evaporation on glass substrates. An electronic flash was used as the light source. The time constant of the photocurrent measured on several samples ranges from 30 sec to 3 min. Whereas bulktraps localised in the narrow band gap of InSb (0.18 eV) can hardly be responsible for the high time constants, it is believed that slow surface traps or traps inside an In₂O₃ layer, covering the InSb film, are responsible for the optical quenching.     

化学腐蚀和硫处理对InSb(111)表面的影响

本文应用俄歇电子能谱和X射线光电子能谱对化学腐蚀和硫处理的InSb表面进行了研究。实验中发现经过CP-4腐蚀以后在样品的表面生成了InSb的氧化层,氧化层中的组分是锑的氧化物明显多于铟的氧化物。样品经过硫处理以后能够除去InSb表面的氧化层并且形成硫化物钝化层。 关键词：     

Optical switch and luminescence properties of sol–gel hybrid organic–inorganic materials containing azobenzene groups and doped with neodymium ions

TiO₂/γ-glycidoxypropyltrimethoxysilane and methyltrimethoxysilane hybrid organic–inorganic material, which contains azobenzene groups and is doped with neodymium ions, was prepared by a low temperature sol–gel technique. The trans-cis-trans photoisomerization cycles of the hybrid film were investigated by a photoirradiation with UV light followed by visible light. An intense room-temperature upconversion emission at 397 nm was also measured from a hybrid film heated at a low temperature of 80 °C upon excitation with a xenon lamp at a wavelength of 580 nm. The mechanism of the upconversion is proposed and indicates that the sequential two-photon absorption process originating from the long-lived ⁴ F _3/2 excited state should be responsible for the up-conversion process. These results indicate that the prepared hybrid materials with multifunctional photonic properties are promising candidates for integrated optics and photonic applications, which would allow directly integrating onto a single chip, the upconversion device with the pump source, and optical data storage and optical switching devices. PACS 42.65.Pe; 78.66.Sq; 81.20.Fw; 82.50.Fv     

An incoherent sub-picosecond X-ray source for time-resolved X-ray-diffraction experiments

Ultrashort bursts of K _α X-ray radiation were generated from fs-laser-produced plasmas. A complete experimental characterization of the X-ray source in terms of spectral, spatial, and temporal properties was performed. The pulse width of the K _α burst is shorter than 250 fs. The time-resolved evolution of a shock wave launched by a synchronized laser pulse in InSb was investigated. The transient change of the rocking curve yields detailed information on the structural changes. Received: 29 June 2000 / Published online: 22 November 2000     

A Study on the Components of MgB2 Thick Film Prepared via HPCVD

Superconducting MgB₂ thick film has been prepared via hybrid physical-chemical vapor deposition method on Al₂O₃ (0001) substrate by using B₂H₆ and magnesium ingot as raw materials reacted from 730 to 830°C for 40 min under 20 to 30 kPa. Its thickness is about 40 µm. The MgB₂ thick film shows T _c (onset) = 39.0 K and T _c (0) = 37.2 K. X-ray diffraction pattern shows that the film grown along (101) direction has small amount of impurities of Mg and MgO. Scanning electron microscopy and energy dispersive X-ray spectroscopy indicated that these impurities existed indeed and were Mg rich. The MgO film was formed on the surface of the MgB₂ thick film to further protect the sample from oxidation. We presented a new mechanism for the formation of the thick film.     

Preparation and optical constants of the nano-crystal and polymer composite Bi4Ti3O12/PMMA thin films

Bismuth titanate, Bi₄Ti₃O₁₂ (BTO), is a typical ferroelectric material with useful properties for optical memory, piezoelectric and electro-optic devices. Its nano-crystals were compounded by the chemical solution decomposition technique. Its structure and size were analyzed by X-ray diffraction and transmissive electron microscopy. The composite thin film of BTO nano-crystals and high transparency polymethylmethacrylate (PMMA) polymer was prepared by spin coating. The transmitted spectrum of BTO/PMMA composite thin film in 300–1500 nm was measured. The film thickness d and the optical constants of the film, such as the refractive index n, the absorption coefficient α, and the extinction coefficient κ were obtained using the data from the transmitted spectrum.     

On the stability of pseudomorphic α-Sn on InSb(001) to temperature and film thickness

Thin films of α-Sn deposited on InSb(001) at 160°C have been studied. The films, grown to a total thickness of 80 Å, showed similar but more pronounced diffraction peaks compared to a monolayer of α-Sn on InSb grown at 30°C. A film of 80 Å was shown to change its behaviour at ∼ 181°C. It is believed to collapse to β-Sn imbedded in a thin film of α-Sn.     

缓冲层对InSb/GaAs薄膜质量的影响

InSb是制作3~5μm红外探测器的重要材料。在GaAs衬底上外延生长InSb,存在的主要问题在于两种材料间14.6%的晶格失配度,会引入较大的表面粗糙度以及位错密度,使外延材料的结构和电学性能均会受到不同程度的影响。通过系列实验,研究了在生长过程中缓冲层对薄膜质量的影响。利用高能电子衍射仪(RHHEED)得到了合适的生长速率和Ⅴ/Ⅲ比,研究了异质外延InSb薄膜生长中低温InSb缓冲层对材料生长质量以及不同外延厚度对材料电学性质的影响。采用原子力显微镜(AFM)、透射电子显微镜(TEM)、X射线双晶衍射(DCXRD)等方法研究了InSb/GaAs薄膜的表面形貌、界面特性以及结晶质量。通过生长合适厚度的缓冲层,获得了室温下DCXRD半高峰宽为172″,77 K下迁移率为64300 cm²·V^-1·s^-1的InSb外延层。     

Effect of surface composition on melting of thin InSb films

We demonstrate the possibility of melting thin (0.1–0.5 μm) InSb films directly in atmosphere under the protective layer of native oxides to obtain high mobility of majority carriers (up to 25 000 cm²/V s). The features of the film synthesis process based on thermal pulsed evaporation of InSb powder in vacuum are studied experimentally. Such a technique makes it possible to provide necessary compositional inhomogeneity of the deposited film for subsequent melting in air.     

真空沉积法制备InSb纳米颗粒

采用真空沉积的方法在SiO₂基片上制备出了纳米InSb颗粒薄膜.利用原子力显微镜对4片样品表面进行分析,从其表面形貌图和三维图中可以观察到有粒径均匀的纳米InSb颗粒形成并且均匀地分布在SiO₂基片表面.实验表明,通过改变镀膜时间可以得到具有不同颗粒尺寸的InSb纳米颗粒,并且颗粒直径与沉积时间和厚度成正比.     

MgB2 thick films deposited on stainless steel substrate with Tc higher than 39K

Thick MgB₂ (magnesium diborate) films, ∼10 μm, with T _c (onset) = 39.4 K and T _c (zero) = 39.2 K have been successfully grown on a stainless steel substrate using a technique called hybrid physical-chemical deposition (HPCVD). The deposition rate is high, ∼6.7 nm/s. The X-ray diffraction (XRD) indicates that it is highly (101) and c-axis oriented. The scanning electron microscope (SEM) images demonstrate that the film grown is in “island-mode”. The uniform superconducting phase in the film is shown by the M-T measurement.     

溅射制备纳米晶GaN∶Er薄膜的室温发光特性

利用直流磁控共溅射方法制备了GaN:Er薄膜.X射线衍射结果显示薄膜为纳米多晶结构,根据谢乐公式,计算得到了GaN薄膜晶粒的平均大小为58nm;透射电子显微镜结果显示为非晶基质中镶嵌了GaN纳米颗粒,尺寸在6—8nm之间;紫外可见谱结果表明在500—700nm的可见光范围内,薄膜的平均透过率大于80%,在紫外可见谱基础上,利用Tauc公式计算得到了纳米晶GaN薄膜的光学带隙为322eV;最后,测量了GaN:Er薄膜的室温光致发光谱,获得了Er³⁺离子在554nm处的强烈绿光发射. 关键词： 纳米晶GaN薄膜 3+掺杂')" href="#">Er³⁺掺杂 光学带隙 光致发光