Soil Profile Concentration Distributions of Aluminum, Gallium, Indium and Thallium across Southeastern Missouri

The soil chemistry of gallium, indium, and thallium is not well defined, particularly with emerging evidence that these elements have toxic properties and may influence food safety. The purpose of this investigation was to estimate the soil concentrations of gallium, indium, and thallium and determine if these elements have a soil chemistry like aluminum and therefore demonstrate significant concentration correlations with aluminum. Twenty-seven soil series were selected, and the elemental concentrations were determined using aqua regia digestion with analytical determination performed using inductively coupled plasma emission-mass spectroscopy. The concentrations of gallium, indium, and thallium generally compared with the known literature. Aluminum-gallium and aluminum-thallium exhibited significant concentration correlations across the soil horizons of the sampled soils. Aluminum, gallium, and thallium did demonstrate concentration increases in soil horizons having illuviation of phyllosilicates, implying these phyllosilicates have adsorption and isomorphic substitution behaviors involving these elements.

高均匀性6英寸GaN厚膜的高速率HVPE生长研究

氢化物气相外延(HVPE)是制备GaN单晶衬底的关键技术,由于生长速率较高,如何控制大尺寸GaN高速率高均匀性生长对于获得高质量GaN衬底具有重要意义。本文针对自主设计研制的6英寸(1英寸=2.54 cm)GaN衬底用HVPE设备,通过数值模拟和实际生长实验,研究了工艺参数如源气体与衬底距离D、分隔气体、HCl流量、NH_(3)载气流量等对高速率生长GaN膜厚度均匀性的影响。数值模拟与生长实验结果发现,采用自研HVPE设备生长GaN厚膜具有高生长速率和高厚度均匀性等特点。研究表明,引入分隔气体及适当增大D值可以有效促进GaCl气体向样品边缘扩散,从而显著提升大尺寸外延厚膜的均匀性。采用最终优化工艺条件获得了厚度约11μm的6英寸GaN厚膜,其厚度不均匀性约±1.5%,生长速率大于60μm/h;随着生长时间的增加,生长速率增大,在生长时间为3 h时,6英寸GaN厚膜厚度达到约700μm,生长速率增大至200μm/h以上,且厚度不均匀性仍在±5%以内。

复合衬底薄膜砷化镓太阳电池技术研究

针对薄膜砷化镓(GaAs)太阳电池,提出了一种复合衬底结构及其一体化制备方法。采用微加工方法使该薄膜砷化镓太阳电池的复合式柔性衬底的厚度降低至15μm,薄膜GaAs太阳电池整体面密度低至95 g/m^(2),光刻形成的金属微孔使砷化镓与衬底背面底电极电学导通。此外,提出的复合衬底一体化制备方法可避免传统薄膜GaAs电池键合过程对砷化镓外延层造成的影响,提高太阳电池工艺可靠性。薄膜GaAs太阳电池电性能测试及疲劳测试结果均表明该一体化制备方法在提高工艺可行性、降低工艺复杂度的同时其电池电性能无明显降低。该复合衬底的薄膜GaAs太阳电池及其一体化制备方法在未来有着广阔的应用前景。

基于MO-TFT工艺的8位32 kS/s电流舵DAC

设计了一个基于金属氧化物薄膜晶体管工艺的8位电流舵数/模转换器(Digital to Analog Converter,DAC),包括定时刷新模块、同步寄存器电路、分段译码电路、开关驱动电路、开关阵列和电流源阵列、多路选择器网络、随机序列发生器。在数字电路中设计定时刷新结构解决了传统的自举逻辑门电荷泄露导致的电流源开关驱动电压的下降,避免了在低频信号下采样出错问题的发生。提出采用差分对偶译码的结构,保证打开和关闭两路信号可以同时到达开关驱动电路,保证驱动电路中电压上升和下降窗口的对称性,减小输出的毛刺;同时利用数字电路中的D触发器和译码电路中的逻辑门实现驱动增强电路,保证可以驱动模拟电路中的高位单位电流源,提高转换速率;利用动态元件匹配(Dynamic Elements Matching,DEM)技术提高DAC的动态性能。后仿真结果表明,所设计的DAC面积为73 mm 2,功耗为6.5 mW,输出电流摆幅为301.46μA,最大转换速率为32 kS/s,在单位电流源的随机匹配误差的标准差为0.1的条件下,奈奎斯特频率下的无杂散动态范围(Spurious-Free Dynamic Range,SFDR)可达到42.43 dB,最大的微分非线性(Differential Nonlinearity,DNL)为0.36 LSB,最大的积分非线性(Integral Nonlinearity,INL)为1.75 LSB,满足生物医学用柔性电子系统的需求。

基于镓基液态金属的柔性传感的研究进展

镓基液态金属(Gallium-based liquid metal,Ga-LM)具有高导电性、高拉伸性、高生物相容性和低毒性等优异性能,在柔性电子领域表现出巨大的应用潜力。然而由于Ga-LM特殊的流变性和氧化性,在控制成型和实际应用方面带来了一定的挑战。基于此,本文综述了Ga-LM在柔性传感领域研究与应用进展,介绍了Ga-LM传感器的不同基底特性及成型工艺,并分析了各自对应的优势、存在的问题和解决方案,旨为Ga-LM在柔性传感器领域的进一步研究和应用提供经验与参考。

十进制量子电阻阵列研究综述

文章综述了十进制量子电阻阵列的制造难点和在电学计量标准化中的应用及前景。通过分析量子霍尔效应的核心原理,探讨了砷化镓(gallium arsenide,GaAs)与石墨烯两种材料在量子电阻阵列中的优势与差异。文章总结了实现十进制量化的关键技术,包括量子霍尔条的制备、载流子密度调控、超导互连与电路误差优化等。此外,文章还强调了量子电阻阵列在国际计量体系中的重要作用,尤其在欧姆与安培重新定义中的贡献,并展望了量子电阻设备的便携化与智能化发展趋势,不仅能够推动电学测量技术的进步,也能够为各类高精度测量应用提供了重要的技术支撑。

非线性光学晶体硒化镓的研究与应用

硒化镓作为光学性能优异的中远红外非线性光学材料,被广泛应用于光电器件领域,但由于其硬度较低,难以生产加工,还需要进一步的研究以改善其力学性能。学者们通过大量的研究发现,通过硒化镓掺杂方式可改善其硬度低的特点,此外,光学性能也能得到增强。该文介绍硒化镓的光学性质与晶体结构,块状硒化镓晶体、二维硒化镓片的制备方法,以及硒化镓在光电器件领域的应用,并对其进一步的研究与应用进行展望。

A review of the most recent progresses of state-of-art gallium oxide power devices

Until very recently, gallium oxide(Ga_2O_3) has aroused more and more interests in the area of power electronics due to its ultra-wide bandgap of 4.5–4.8 eV, estimated critical field of 8 MV/cm and decent intrinsic electron mobility limit of250 cm2/(V·s), yielding a high Baliga's figures-of-merit(FOM) of more than 3000, which is several times higher than GaN and SiC.In addition to its excellent material properties, potential low-cost and large size substrate through melt-grown methodology also endows β-Ga_2O_3 more potential for future low-cost power devices. This article focuses on reviewing the most recent advances ofβ-Ga_2O_3 based power devices. It will be starting with a brief introduction to the material properties of β-Ga_2O_3 and then the growth techniques of its native substrate, followed by the thin film epitaxial growth. The performance of state-of-art β-Ga_2O_3 devices, including diodes and FETs are fully discussed and compared. Finally, potential solutions to the challenges of β-Ga_2O_3 are also discussed and explored.

Review of gallium oxide based field-effect transistors and Schottky barrier diodes

Gallium oxide(Ga_2O_3), a typical ultra wide bandgap semiconductor, with a bandgap of ~4.9 e V, critical breakdown field of 8 MV/cm, and Baliga's figure of merit of 3444, is promising to be used in high-power and high-voltage devices.Recently, a keen interest in employing Ga_2O_3 in power devices has been aroused. Many researches have verified that Ga_2O_3 is an ideal candidate for fabricating power devices. In this review, we summarized the recent progress of field-effect transistors(FETs) and Schottky barrier diodes(SBDs) based on Ga_2O_3, which may provide a guideline for Ga_2O_3 to be preferably used in power devices fabrication.

Review of deep ultraviolet photodetector based on gallium oxide

Ultraviolet(UV) photodetectors(PDs) have drawn great attention in recent years due to their potential application in civil and military fields. Because of its ultrawide bandgap, low cost, strong radiation hardness, and high thermal and chemical stability with high visible-light transparency, Ga_2O_3 is regarded as the most promising candidate for UV detection.Furthermore, the bandgap of Ga_2O_3 is as high as 4.7–4.9 eV, directly corresponding to the solar-blind UV detection band with wavelength less than 280 nm. There is no need of doping in Ga_2O_3 to tune its bandgap, compared to AlGaN, MgZnO,etc, thereby avoiding alloy composition fluctuations and phase separation. At present, solar-blind Ga_2O_3 photodetectors based on single crystal or amorphous Ga_2O_3 are mainly focused on metal–semiconductor–metal and Schottky photodiodes.In this work, the recent achievements of Ga_2O_3 photodetectors are systematically reviewed. The characteristics and performances of different photodetector structures based on single crystal Ga_2O_3 and amorphous Ga_2O_3 thin film are analyzed and compared. Finally, the prospects of Ga_2O_3 UV photodetectors are forecast.

Effect of gallium addition on microstructure and properties of Ag-Cu-Zn-Sn alloys＊

The effects of Ga on microstructures and mechanical properties of the cadmium-free silver based brazing filler metals have been investigated. The results indicated that C,a additions had the noticeable effect on the microstructure, especially on the shape of the phases. With the increase of Ga addition, the amount of eutectic structure increased, and the acicular eutectic structure changed into the fine eutectic structure with micro-vermiform and rod-like shape. When the addition of Ga was 3.0 wt. %, none of defects exist in the microstructure of the brazed joint. The tensile strength increased from 382 MPa to 511 MPa with the content of Ga increasing from 0 to 3.0 wt. %.

Gallium trichloride-catalyzed conjugate addition of indole and pyrrole to α,β-unsaturated ketones in aqueous media

Michael addition of indole and pyrrole to a variety of α, β-unsaturated ketones was efficiently promoted by a catalytic amount of GaCl3 in aqueous media to afford the corresponding products in good to excellent yields.

Hydride vapor phase epitaxy for gallium nitride substrate

Due to the remarkable growth rate compared to another growth methods for gallium nitride(GaN)growth,hydride vapor phase epitaxy(HVPE)is now the only method for mass product GaN substrates.In this review,commercial HVPE systems and the GaN crystals grown by them are demonstrated.This article also illustrates some innovative attempts to develop homebuilt HVPE systems.Finally,the prospects for the further development of HVPE for GaN crystal growth in the future are also discussed.

Recovery of gallium from zinc concentrate by pressure oxygen leaching

Zinc concentrate with high gallium content is one of the main resources of gallium.The gallium presents in the form of isomorphism in tetrahedron coordination with sulfur in sphalerite.The research was to investigate the amenability of zinc concentrate with high gallium to pressure oxygen leaching.The particle size,sulfuric acid concentration,oxygen partial pressure,additive amount,and time of reaction were studied.The extraction yields of gallium and zinc are 86%and 98%,respectively.The optimal condition is 100 g of zinc concentrate with particle size smaller than 38 lm,sulfuric acid concentration150 g L-1,leaching temperature 150℃,leaching time120 min,oxygen partial pressure 0.7 MPa,additive amount of 0.2 wt%.

Separation of indium (Ⅲ), gallium (Ⅲ), and zinc (Ⅱ) with Levextrel resin containing di(2-ethylhexyl) phosphoric acid (CL-P204): Part I. Selection of separation conditions

A kind of Levextrel resin separation process was developed for separation ofindium (III), gallium (III), and zinc (II) from aqueous sulfate solution with Levextrel resincontaining di(2-ethylhexyl) phosphoric acid (CL-P 204). The aim of the research is to collectpreliminary results for a pilot-scale production. Properties of adsorbing indium (III), gallium(III), and zinc (II) from sulfate solution with the Levextrel resin were first studied by batchoperation and column operation. The optimum pH, adsorption capacities and concentrations ofstripping agents for indium (III), gallium (III) were tested. The separation order of indium (III),gallium (III), and zinc (II) from sulfate solution with CL-P 204 Levextrel resin was found thatindium (III) could be first separated by adsorbing at the acidity of 1.0 mol/L whereas gallium (III)and zinc (II) could not, and they were adsorbed together by adsorbing at pH =2.8, then separatedfrom each other by stripping with 0.1 and 0.5 mol/L hydrochloric acid, respectively. The recoveriesof three metal ions were all higher than 99 percent. The cyclic properties of this resin are well.

Preparation, characterization and nonlinear optical properties of colloidal gallium arsenide nanocrystals

GaAs nanocrystals were prepared via a simple mechanical ball milling technique. The prepared GaAs nanocrystals have high purity and could form colloidal ethanol suspension without any surfactant additives. The colloidal GaAs nanocrystal suspension displayed excellent two-photon absorption property over the visible and near-infrared region from 490 nm to 1064 nm, which enables it to become a promising broadband optical limiting material.

Synthesis and purification of trialkyl compounds of gallium and indium

The The research progress in trialkyl compounds of gallium andindium was discussed from two aspect, one was the chemical synthesisof the compounds and the other was the purification of them. Thereare three synthesis routes be- ing reported in the first aspect, i.e.the route staring form pure metal, the route starting from the puremetal trihalides, and the electrochemical route. In the secondaspect, the purifying methods of decomposition-distillation and zonerefining were reviewed.

Tetrahydrofuran Ring Opening with Acyl Chlorides or Anhydrides Catalyzed by Gallium Triiodides: A Novel and Facile Method for the Preparation of Iodo Esters

Tetrahydrofuran ring can be opened with acyl chlorides or anhydrides catalyzed by gallium triiodides to afford iodo esters under mild conditions in good yields.

Spectrofluorimetric Determination of Trace Amounts of Gallium with Salicylaldehyde Benzoylhydrazone

The fluorescent reagent salicylaldehyde benzoylhydrazone(SABH) was synthesized and its ionization constants were estimated spectrophotometrically. The fluorescent reaction of this reagent with gallium was studied. Based on this chelation reaction, a spectrofluorimetric method was developed for the determination of gallium in a water medium at pH 3.2. Under these conditions, the Ga SABH complex has excitation and emission maxima at 372 and 455 nm, respectively. The linear range of the method was 0～150 μg/L and the detection limit was 0.36 μg/L of gallium when a standard addition method was used in the assay. The molar ratio of gallium to the reagent was 1∶3. The interference of other ions was studied. The extraction with n butyl acetate from a 6 mol/L hydrochloric acid medium was used to separate Ga from the interfering elements in semiconductor silicon and geological samples, and themethod has been successfully applied to the determination of gallium in these samples.

Review Recent progress in the determination of gallium, indium, and thallium

This mini-review covers the literatures of the determination of gallium, indium, and thallium by instrumental analysis with computer-assisted searching over the period of 1994 to 2003. Some papers appearing in the early of 2004 are also included. Because the rapid progress in the instrument has been made, these new papers are prioritized in selection in the similar papers. The contents are considered to be separation and preconcentration, spectrophotometry, spectrofluorimetry, electroanalyses, atomic absorption spectrometry, inductively coupled plasma-atomic emission spectrometry, inductively coupled plasma-mass spectrometry and so forth.