Determination of the Melt Undercooling Required for Producing Al x Ga y In1 – x – y Sb1 – z Bi z /InSb Heterostructures

Conditions for temperature-gradient epitaxial growth of Al _x Ga _y In_{1 – x – y} Sb_{1 – z} Bi _z /InSb heterostructures are examined. The factors are established which determine the initial melt undercooling required for preventing the thermal degradation of the substrate.     

A comparison of strain relief behaviour of In x Ga1− x As alloy on GaAs (001) and (110) substrates

A comparative study on the strain relief behaviour of epitaxially grown In _x Ga_{1 – x} As (where 0.1 × 1) alloys on GaAs (001) and (110) were carried out using transmission electron microscopy (TEM) and high resolution X-ray diffraction (XRD). Three different strain relief mechanisms related to the formation of misfit dislocations (MDs) were observed. The dominant strain relief process can be a single mechanism or a combination of two of the three mechanisms depending on the substrate orientation and the in content.     

原子团离子在Al_(x)Ga(1-x)As基体组分SIMS定量分析中的应用

通过检测原子团离于MCs 和MAs－（M是基体元素）对AlxGa1-xAs基体组分进行了定量的分析，考察了MIQ－156SIMS上所测这些原子团离子的能量分布及其对分析结果的影响，并对正、负SIMS测量方法做出比较。     

Mixtures of (N2)1−x : (O2) x at High Pressures and Low Temperatures

We performed Raman measurements at 18 K and pressures up to 25 GPa in order to construct a tentative phase diagram of the (N ₂)_1–x :(O ₂)_x –system at low temperatures. We varied the composition of the mixed system over the whole concentration range. Here we focused on the systems with high nitrogen concentration and pressures above 2 GPa. It is known that at room temperature oxygen is highly solvable in the –phase of N ₂. The experimental results show that oxygen suppresses the disorder–order transition –N ₂.     

In(x)Ga(₁-x)As nanowires on silicon: one-dimensional heterogeneous epitaxy, bandgap engineering, and photovoltaics

We report on the one-dimensional (1D) heteroepitaxial growth of In(x)Ga(1-x)As (x = 0.2-1) nanowires (NWs) on silicon (Si) substrates over almost the entire composition range using metalorganic chemical vapor deposition (MOCVD) without catalysts or masks. The epitaxial growth takes place spontaneously producing uniform, nontapered, high aspect ratio NW arrays with a density exceeding 1 × 10(8)/cm(2). NW diameter (～30-250 nm) is inversely proportional to the lattice mismatch between In(x)Ga(1-x)As and Si (～4-11%), and can be further tuned by MOCVD growth condition. Remarkably, no dislocations have been found in all composition In(x)Ga(1-x)As NWs, even though massive stacking faults and twin planes are present. Indium rich NWs show more zinc-blende and Ga-rich NWs exhibit dominantly wurtzite polytype, as confirmed by scanning transmission electron microscopy (STEM) and photoluminescence spectra. Solar cells fabricated using an n-type In(0.3)Ga(0.7)As NW array on a p-type Si(111) substrate with a ～ 2.2% area coverage, operates at an open circuit voltage, V(oc), and a short circuit current density, J(sc), of 0.37 V and 12.9 mA/cm(2), respectively. This work represents the first systematic report on direct 1D heteroepitaxy of ternary In(x)Ga(1-x)As NWs on silicon substrate in a wide composition/bandgap range that can be used for wafer-scale monolithic heterogeneous integration for high performance photovoltaics.     

In(1-x)Ga_xAs/Inp(111)B异质结的LPE生长

用近平衡降温生长的LPE技术生长了In_(1-x)Ga_xAs/InP(111)B异质结,研究了在饱和溶液附近,“Ga”组分的偏离对“X”值,带隙(Eg)、荧光峰值波长(λg)、晶格失配[△a/a=(a_(InGaA)·-a_(Inp))/a_(Inp)]的影响:观察了异质结的晶格失配对界面形貌及表面形貌的影响;并分析了在较宽的负晶格匹配范围内有较好的界面和表面形貌的原因。     

Effect of Al content on the performance of Cu(In1−x Al x )S2 synthesized by hydrothermal solution processing

Al doped CuInS₂ (CIS) material was prepared by a low cost and non vacuum wet chemical process. The effect of aluminum concentrations on the crystal structure, morphology, percentage composition, and band gap of Cu(In_{1? x} Al _x )S₂ were investigated. The X-ray diffraction (XRD) shows that the size of crystal grains decreased with the increase of Al concentrations. Scanning electron microscope presents the size of particles is gradually become smaller with Al concentrations increase. The reason for these phenomenons is Al concentrations cause the solution to a colloidal state. Binding between ions and grains growing together gradually become harder in a colloidal solution. In situ XRD tests show that CIS perform exceptional thermal stability below 798 K but decomposed to Cu₂S and In₂S₃ at the temperature higher than 798 K. Results of energy dispersive X-ray analysis (EDAX) show the nearly stoichiometry composition of Cu(In_{1? x} Al _x )S₂ which matched well with the ratio of the precursor solution. The transmission spectra show that spectral transmittance decrease with decreasing contents of Al. The band gap of Cu(In_{1? x} Al _x )S₂ is continuously tuned in a range of 1.56–1.92 eV as Al/(Al + In) content ratio varied from 0 to 0.3. Finally, the mechanism of Al concentration on the properties of Cu(In_{1? x} Al _x )S₂ was discussed briefly.     

La(2-x)/3(Ag(0)1-2x/3Ag(I)x)TiO3光致变色粉体的制备与表征

通过固相反应法合成了具有光致变色性质的La(2-x)/3(Ag(0)1-2x/3Ag(I)x)TiO3(简称Ag-LST)钙钛矿结构复合氧化物粉体,采用XRD、XPS、ICP和SEM等实验技术对Ag-LST进行了表征.结果表明,Ag-LST具有立方晶相钙钛矿结构,其表面层元素组成为Ag:La:Ti=0.45:0.60:1.00.研究了Ag-LST的光致变色性质,在紫外光(300W汞灯)下照射Ag-LST 1min,样品的颜色从棕黄色转变为蓝紫色;在可见光(500W氙灯)下照射Ag-LST 1h,样品恢复为原来的棕色.Ag-LST的光致变色性质可能与Ag(0)-Ag(I)相互转换有关.     

Composition-dependent structural, optical and electrical properties of In x Ga1−x N (0.5 ≤ x ≤ 0.93) thin films grown by modified activated reactive evaporation

In this report, we have studied the compositional dependence of structural, optical and electrical properties of polycrystalline In _x Ga_1?x N thin films grown by modified activated reactive evaporation. The growth was monitored by optical emission spectroscopy. The thickness of the films was in the range ~600–800 nm. The phase, crystallinity and composition of the films were determined by X-ray diffraction, Raman spectroscopy and energy dispersive X-ray analysis. The surface morphology was studied by atomic force microscopy. The band gaps of these films obtained from transmittance and photoluminescence measurements were found to vary from 1.88 to 3.22 eV. All the films show n-type conductivity. The carrier concentration was found to be decreasing with increase in gallium incorporation which is in good agreement with the free carrier absorption observed in transmittance spectra.     

High Pressure Synthesis of (La1?xSrx)8O20, (0.25 ≤ x ≤ 0.65) with a Wide Solubility Range and High Cu-Valence

With an attempt to increase the Cu valence, we synthesized the (La_1–x Sr _x )₈Cu₈O_20– (8-8-20 phase) compounds with large x using an O₂-HIP apparatus. By heat treatment in a high-pressure of oxygen gas (40 MPa), the 8-8-20 compounds were stabilized in the range of 0.25 x 0.65. Their crystal structures, characterized by x-ray Rietveld refinement and electron diffraction, are tetragonal, space group P4/mbm. The formal copper valence was found to increase with Sr concentration from 2.24 at x = 0.25 to 2.63 at x = 0.65, keeping the oxygen content constant around 20.0. Electrical resistivity and magnetic susceptibility showed only metallic behavior from room temperature down to 5 K with no sign of superconductivity.     

Electrical properties of Pd–Au/(In x –Sn1 – x ) Oxide/Si(p)/Al heterojunction diodes

Current–voltage (I–V ) and capacitance–voltage – characteristics of [Pd–Au/( – ) Oxide/Si(p)/Al] semiconductor oxide semiconductor (SOS) solar cells were measured in the temperature range between 300 and 500 K. The dark forward current–voltage curves were found to be independent of temperature. Consequently, the diode quality factor was temperature dependent. Analysis of the data indicated that the predominant carrier transport mechanism of the samples in the intermediate bias voltage region was thermionic field emission and recombination tunneling. From the experimental data it was found that, the open circuit voltage – , the short circuit current – and the fill factor 0.28–0.32, under illumination of 1124 lux.     

Dielectric properties of rutile structure (Zn₁/₃B₂/₃)x(TiySn(1-y))(1-x)O₂ (B=Nb⁵+,Ta⁵+) at microwave frequencies

The microwave dielectric properties of rutile (Zn?/? B?/?)x(TiySn(1-y))(1-x)O? (B=Nb?+,Ta?+, 0.05 ≤ x ≤ 0.35, y = 0.2, 0.8) were investigated with structural characteristics. A single phase with tetragonal rutile (P4?/mnm, no. 136, Z = 2) structure was obtained through the entire range of compositions. With an increase of (Zn?/?B?/?)O? content, the dielectric constant (K) of sintered specimens with (Ti?.?Sn?.?)O? increased, whereas that of the specimens with (Ti?.?Sn?.?)O? decreased. The temperature coefficient of resonant frequency (TCF) of sintered specimens was dependent upon oxygen octahedral distortion and/or cations bond valence of the rutile structure. The quality factor (Qf) was dependent upon (Zn?/?B?/?)O? content, and the specimens with (Ti?.?Sn?.?)O? showed larger Qf values than those with (Ti?.?Sn?.?)O? for the same content of (Zn?/?B?/?)O?.     

Highly enhanced photocatalytic performance of Zn(1−x)MgxO/rGO nanostars under sunlight irradiation synthesized by one-pot refluxing method

The current research presents a simple, coast-effective, and one-pot refluxing method to synthesize Zn_(1?x)Mg_xO nanostructures, which were decorated on graphene oxide (GO) sheets. In the first step, the effect of refluxing time on structure and morphology of the pristine ZnO nanostructures was investigated. X-ray diffraction (XRD) patterns indicated that the pristine ZnO nanostructures were formed after 8?h of the refluxing process. Field emission electron microscope (FESEM) images showed that stars-shape ZnO nanostructures were formed after 10?h of refluxing time. Further refluxing process for 12?h showed that morphology and structure of the ZnO nanostructures were not changed. However, after 14?h additional phases were formed. Therefore, ZnO and Zn_(1?x)Mg_xO nanostars that were decorated on GO sheets were synthesized during 10?h. XRD patterns indicated that GO sheets were changed into reduced graphene oxides (rGO) during the refluxing process. Transmission electron microscope (TEM) images revealed that ZnO nanostars with more branches were decorated on rGO sheets. However, the TEM images showed that the morphology of Zn_xMg_(1?x)O/rGO nanocomposites were changed significantly with the increase of Mg concentration up to 6%. Photocatalytic performance of the products was examined under natural sunlight irradiation. The results showed that the rGO and Mg concentrations had significant roles in the photocatalytic performance of ZnO nanostars. The concentrations of Mg and rGO increased up to 4% were the optimum concentration for enhancing photocatalytic performance of Zn_(1?x)Mg_xO/rGO nanocomposites. In addition, room temperature photoluminescence (PL) spectroscopy and photocurrent measurement results indicated that Mg and rGO with optimum concentration caused decrease of electron-hole recombination rate.     

共沉淀法合成球形正极材料xLi2MnO3·(1-x)Li(Ni1/3Co1/3Mn1/3)O2(x=0.2、0.4、0.6)及其性能研究

以氨水作为络合剂,采用氢氧化物共沉淀法合成了球形富锂锰基正极材料xLi2MnO3·(1-x)Li(Ni1/3Co1/3Mn1/3)O2(x=0.2、0.4和0.6),并对合成的不同组分样品材料的化学成分、结构、形貌和电化学性能进行了表征。结果表明,样品材料的化学组分与其理论含量相同,随着x 的增大,材料的粒度变小,在电压范围为2.5~4.6V条件下进行充放电性能测试时,材料的首次充放电容量随着x 值减小而增加,且当x=0.2时,材料在不同倍率条件下具有最大的放电容量。     

CaTiO3对(1-x)ZnAl2O4-xMg2TiO4(x=0.21)微波介质陶瓷结构和性能的影响

利用常规固相法制备了ZnAl₂O₄-Mg₂TiO₄-CaTiO₃陶瓷, 研究了CaTiO₃对其相成分、微观组织结构和微波介电性能的影响规律. 结果表明, CaTiO3能有效地改善(1-x)ZnAl₂O₄-xMg₂TiO₄(x=0.21)材料的烧结性能, 使其致密化温度降低150℃. ZnAl₂O₄-Mg₂TiO₄-CaTiO₃陶瓷体系中包括ZnAl₂O₄基尖晶石相、CaTiO₃、MgTi₂O₅和Zn₂Ti₃O₈相, 当烧结温度高于1400℃时, Zn₂Ti₃O₈相消失. 随着CaTiO₃含量的增加, 体系中CaTiO₃相含量增加而MgTi₂O₅相含量减少, 且CaTiO₃具有显著地调节谐振频率温度系数的作用. 当在(1-x)ZnAl₂O₄-xMg₂TiO₄(x=0.21)体系中掺入6mol%的CaTiO₃添加剂时, 经1400℃烧结后能获得温度稳定性好的微波介质陶瓷材料, 其微波介电性能为：ε_r=11.8, Q·f=88080GHz, τ_f=-7.8×10^－6/℃.     

The relationship between the mean dopant-ion radii and conductivity of co-doped ZnO systems, Zn1−x−y M x M′ y O (M, M′ = Al, In, Ga, Y)

The conductivities of the Zn_1–x–y M _x M _y O (M, M = Al, In, Ga, Y) and Zn_1–x M _x O (M = Al, In, Ga) systems were measured from room temperature to 1173 K in order to elucidate a dominant parameter of the conducting mechanism. The conductivity at 873 K first increased with the dopant content. However, it showed a maximum value at a given dopant content, and then gradually decreased. For the samples with the same dopant content, their conductivity at 873 K was strongly dependent on the mean dopant-ion radii, and reached a maximum value at around 0.51 Å of the mean dopant-ion radii. The results suggested that the conductivity of the system would be influenced not only by the dopant content, but also by the mean dopant-ion radii. It was found that the co-doped ZnO system of Zn_0.995Al_0.003In_0.003O had a conductivity higher than that of the other usual mono-doped system.     

High performance <Emphasis Type="Italic">in vivo</Emphasis> near-IR (>1 μm) imaging and photothermal cancer therapy with carbon nanotubes

Short single-walled carbon nanotubes (SWNTs) functionalized by PEGylated phospholipids are biologically non-toxic and long-circulating nanomaterials with intrinsic near infrared photoluminescence (NIR PL), characteristic Raman spectra, and strong optical absorbance in the near infrared (NIR). This work demonstrates the first dual application of intravenously injected SWNTs as photoluminescent agents for in vivo tumor imaging in the 1.0–1.4 μm emission region and as NIR absorbers and heaters at 808 nm for photothermal tumor elimination at the lowest injected dose (70 μg of SWNT/mouse, equivalent to 3.6 mg/kg) and laser irradiation power (0.6 W/cm²) reported to date. Ex vivo resonance Raman imaging revealed the SWNT distribution within tumors at a high spatial resolution. Complete tumor elimination was achieved for large numbers of photothermally treated mice without any toxic side effects after more than six months post-treatment. Further, side-by-side experiments were carried out to compare the performance of SWNTs and gold nanorods (AuNRs) at an injected dose of 700 μg of AuNR/mouse (equivalent to 35 mg/kg) in NIR photothermal ablation of tumors in vivo. Highly effective tumor elimination with SWNTs was achieved at 10 times lower injected doses and lower irradiation powers than for AuNRs. These results suggest there are significant benefits of utilizing the intrinsic properties of biocompatible SWNTs for combined cancer imaging and therapy.     

共沉淀法合成球形正极材料xLi2MnO3·（1-x）Li(Ni1/3Co1/3Mn1/3)O2（x=0.2、0.4、0.6）及其性能研究

以氨水作为络合剂,采用氢氧化物共沉淀法合成了球形富锂锰基正极材料xLi2MnO3·(1-x)Li(Ni1/3Co1/3Mn1/3)O2(x=0.2、0.4和0.6),并对合成的不同组分样品材料的化学成分、结构、形貌和电化学性能进行了表征。结果表明,样品材料的化学组分与其理论含量相同,随着x的增大,材料的粒度变小,在电压范围为2.5~4.6V条件下进行充放电性能测试时,材料的首次充放电容量随着x值减小而增加,且当x=0.2时,材料在不同倍率条件下具有最大的放电容量。