《半导体材料》课程改革

根据《半导体材料》课程的自身特点,对该课程在教学内容、教学形式和教学考核上进行了综合改革。改革目的在于探索培养高素质半导体材料人才的教学方法,提升学生的自我学习能力、资料收集和整合能力以及在半导体材料领域的创新能力。

基于超声波半导体靶材自动检测系统的研究

为了检测半导体靶材内部氧化物杂质、未焊合、空隙等缺陷,且在检测过程中不对产品造成损伤,提出了一种利用超声波的半导体靶材自动检测系统。该系统采用相控阵探头水浸检测,三轴移动系统中X轴和Y轴检测速度达到1000 mm/s,可对铜、铝、钴、镍等靶材内部夹杂、分层、气泡、内裂等细小缺陷进行检测,可判断缺陷大小、位置和深度并形成报告。实验结果表明:该系统可以发现靶材内部当量直径0.3 mm大小的缺陷,且具有较高的检测效率、稳定性和可靠性。

半导体芯片行业用金属溅射靶材市场分析

本文首先介绍了半导体芯片行业用金属溅射靶材的应用背景、溅射原理以及靶材分类,随后对各种溅射靶材的特性和应用进行了详细描述,然后对国内外主要的7家半导体芯片用溅射靶材生产企业的行业地位、发展现状、优势产品及其市场份额进行了全面分析,最后,还对半导体芯片溅射靶材合格供应商的认证过程特点进行了深入分析和总结。

设备部件延寿的灰色多指标畸变预测模型

针对设备部件延寿预测问题,首先,提出了上下限两种异常畸变指标,并给出灰色多指标延寿畸变预测模型的架构图和延寿预测示意图。其次,运用灰色系统方法分别构建了两阶段灰色预测模型,在第一阶段构建了灰色上下限畸变预测模型,得到下一次发生畸变的日期;在第二阶段构建了GM(1,1)模型,对设备部件延寿以及上下限指标的异常值进行预测。同时,对模型的预测精度进行检验和分析,并根据模型的预测结果确定了设备部件延寿的时间。最后,以半导体制造业设备靶材延寿为实际应用案例,验证了该模型的有效性和可行性,为合理制定部件的最优维护更换时间以及对降低企业运维成本具有重要指导意义。

激光刻蚀与化学腐蚀结合法制备量子线(点)结构

目前制备量子线(点)主要采用微细加工或自组织方法,但存在沾污或分布规律不可控等局限性.介绍了一种既可避免这些缺点而且简单易行的方法:利用激光刻蚀与化学腐蚀相结合的方法,在InP单晶片上刻蚀出了台宽为1μm且分布规则的条状结构和网格结构,通过化学方法进一步腐蚀后,可使台宽减小到160nm左右.

氧在SnO_2(110)面吸附机理的研究

用EHMO方法计算了SnO_2(110)面原子簇模型,并计算了表面存在氧空位和氧原子吸附的情况.计算结果表明,表面四配位锡原子是吸附中心,因电子得失而引起的原子净电荷变化是完全定域的.四配位锡原子的净电荷变化很明显,而五配位锡原子吸附的净电荷变化很小.

Deposition of Thick SiO_2 from Tetraethylorthosilicate and H_2O by Plasma-Enhanced CVD

The deposition of silicon dioxide by plasma enhanced chemical vapor deposition from tetraethylorthosilicate (TEOS) and H_2O has been studied.Silicon oxide with refractive index of 1453 has been obtained.Tests on the 51mm wafers show that both thickness uniformity of ±15% and constant refractive index of 1453 can be achieved.By raising the deposition temperature,the qualities have been improved,while the deposition rate decreased.A SiO_2 thick film deposition technique has been developed combining TEOS-PECVD technique with high temperature annealing.

Peculiar Nonlinear Depletion in Double-Layered Gated Si-δ-Doped GaAs

The low-temperature measurement of Hall effect of the two-dimensional electron system in a double-layered gated Si-δ-doped GaAs is presented.A complex peculiar nonlinear dependence of the depletion on gate voltage is observed.The nonlinearity is also explained on the basis of the assumption that the double-capacity model consists of two δ-doped two-dimensional electron layers and a metallic gate,and the experimental result that the electron mobility is linear with the electron density on a log-log scale.

CdS Thin Films Deposited by CBD Method on Glass

CdS thin films were prepared by chemical-bath-deposited method and the effect of temperature and time on the properties of CdS thin films was studied. Independent of the deposited temperature, the growth was mainly controlled by the ion-by-ion growth mechanism at the beginning of the film deposition, then the cluster-by-cluster mechanism came to be dominant. The growth rate increased faster with the increasing of temperature until the thickness reached the limitation, then thickness instead become thinner. The scanning electron micro- scope results revealed that the morphology of the CdS film changed from pinholes to rough, inhomogeneous surface with increasing deposition time and deposition temperature. The X- ray diffraction results showed the film structure was a mixture of two phases： hexagonal and cubic, and it was very important to controll deposition time to the film＇s crystal phase. All films in depth of approxilnate 100 nm existed above 65% transmittance, the absorption edge became ＂red-shift＂ with temperature rising. At 60 and 70℃, with 20 min deposited-time, the energy band gap was more than 2.42 eV and decreased with time, while at 80 and 90℃ the energy band gap was less than 2.42 eV and increased little when the time changed from 10min to 15 nfin at 80℃.

Thermodynamic analysis of growth of ternary Ⅲ-Ⅴ semiconductor materials by molecular-beam epitaxy

Thermodynamic models for molecular-beam epitaxy（MBE） growth of ternary Ⅲ-Ⅴ semiconductor materials are proposed.These models are in agreement with our experimental materials InGaP/GaAs and InGaAs/InP,and reported GaAsP/GaAs and InAsP/InP in thermodynamic growth.The lattice strain energy △G and thermal decomposition sensitive to growth temperature are demonstrated in the models simultaneously.△G is the function of the alloy composition,which is affected by flux ratio and growth temperature directly.The calculation results reveal that flux ratio and growth temperature mainly influence the growth process.Thermodynamic model of quaternary InGaAsP/GaAs semiconductor material is discussed also.

A Polaron in a Quantum Dot quantum Well

The polaron effect in a quantum dot quantum well (QDQW)system is investigated by using the perturbation method. Both the bound electron states outside and inside the shell well are taken into account . Numerical calculation on the CdS/HgS QDQW shows that the phonon correction to the electron ground state energy is quite significant and cannot be neglected.

Research advances of light-driven hydrogen evolution using polyoxometalate-based catalysts

With the increasing concerns to energy shortage and environmental problems in modern society,the development of cheap,clean,and sustainable energy alternatives has been attracting tremendous attention globally.Among various strategies of renewable energy exploration,solar-driven water splitting into its compositional elements H2 and O2 is an ideal approach to convert and store renewable solar energy into chemical bonds.In recent few decades,as an emerging new type of catalysts,polyoxometalates(POMs)have been widely utilized for water splitting due to their versatile synthetic methodology and highly tunable physicochemical and photochemical properties.This critical review addresses the research advances of light-driven hydrogen evolution using polyoxometalate-based catalysts,including plenary POMs,transition-metal-substituted POMs,POM@MOF composites,and POM-semiconductor hybrids,under UV,near UV and visible light irradiation.In addition,the catalytic mechanism for each reaction system has been thoroughly discussed and summarized.Finally,a comprehensive outlook of this research area is also prospected.

Solid-phase Crystallization of Hydrogenated Amorphous Silicon on Glass Substrates

Amorphous silicon films prepared by PECVD on glass substrate have been crystallized by conventional furnace annealing and rapid thermal annealing(RTA), respectively. From the Raman spectra, X-ray diffraction and scanning electron microscope, it is found that the grain size is crystallized at 850℃ in both techniques. The thin film made by RTA is smooth and of perfect structure, the thin film annealed by FA has a highly structural disorder. An average grain size of about 30nm is obtained by both techniques.

Photoluminescence Spectra of Disordered and Ordered Ga_(0.52)In_(0.48)P

Temperature-dependence and excitation-intensity-dependence of photoluminescence spectra for both disordered and ordered Ga 0.52 In 0.48 P are measured. The disordered sample is characterized by its single peak photoluminescence spectrum which is excitation-intensity independent and has different activation energy at different temperature region. The ordered sample shows double peaks, the intensity of the high-energy peak has an anomalous increase firstly and quenches afterwards. The relative phenomena are reasonably explained in terms of lattice ordering and orientation superlattice model.

Comparison of Ge_xSi_(1- x) Grown by UHV/CVD from Si_2H_6/GeH_4 and SiH_4/GeH_4

Using double crystal X-rays diffraction (DCXRD) and atomic force microscopy (AFM), the results of Ge x Si 1- x grown by UHV/CVD from Si 2H 6 and SiH 4 are analyzed and compared. Adsorbates can migrate to the energy-favoring position due to the slow growth rate from SiH 4. In this case, a Si buffer that isolates the effect of substrate on epilayer could not be grown, which results in a pit penetrating into epilayer and buffer. The FWHM is 0.055° in DCXRD from SiH 4. The presence of diffraction fringes is an indication of an excellent crystalline quality. The roughness of the surface is improved if grown by Si 2H 6; however, the crystal quality of the Ge x Si 1- x material became worse than that from SiH 4 due to much larger growth rate from Si 2H 6. The content of Ge is obtained from DCXRD, which indicates the growth rate from Si 2H 6 is largest, then GeH 4, and that from SiH 4 is least.

Formation of GaN Nanowires by Ammoniating Ga_2O_3 Films Deposited on Oxidized Al Layers on Si Substrate

Large quantities of gallium nitride(GaN) nanowires have been prepared via ammoniating the Ga2O3 films deposited on the oxidized aluminum layer at 950 ℃ in a quartz tube. The nanowires have been confirmed as crystalline wurtzite GaN by X-ray diffraction, X-ray photoelectron spectrometry scanning electron microscope and selected-area electron diffraction. Transmission electron microscope(TEM) and scanning electron microscopy(SEM) reveal that the nanowires are amorphous and irregular, with diameters ranging from 30 nm to 80 nm and lengths up to tens of microns. Selected-area electron diffraction indicates that the nanowire with the hexagonal wurtzite structure is the single crystalline. The growth mechanism is discussed briefly.

InGaAsP/InP Double Quantum Well Intermixing Induced by Phosphorus Ion Implantation

A quantum well intermixing（QW1） investigation on double quantum well（DQW） structure with two different emitting wavelength caused by phosphorus ion implantation and following rapid thermal annealing （RTA） was carried out by means of photoluminescence（PL）. The ion implantation was performed at the energy of 120 keV with the dose ranging from 1 × 10^11cm^-2 to 1× 10^14cm^-2. The RTA was performed at the temperature of 700 ℃ for 30 s under pure nitrogen protection. The PL measurement implied that the band gap blue-shift from the upper well increases with the ion dose faster than that from lower well and the PL peaks from both QWs remained well separated under the lower dose implantation（-1 × 10^11cm^-2） indicating that the implant vacancy distribution affects the QWl. When the ion dose is over - 1 × 10^12cm^-2, the band gap blue-shift from both wells increases with the ion dose and finally the two peaks merge together as one peak indicating the ion implantation caused a total intermixing of both quantum wells.

Carriers-assisted Enhanced Ferromagnetism in AI-doped ZnMnO Nano-crystallites

Zn0.95-zAlxMn0.050 （x=0, 0.03, 0.05, and 0.07） dilute magnetic semiconductor materials have been synthesized by sol-gel auto-combustion technique. The effect of A1 doping on the structural, electrical, and magnetic properties has been investigated. X-ray diffraction studies demonstrate the existence of single phase characteristic hexagonal wurtzite type crystal structure, similar to the host ZnO, in all the synthesized compositions. Although, the microscopic images revealed that the grains were clustered, yet some individual grains could be seen to have hexagonal texture. Electrical resistivity was observed to decrease with the rise of temperature up to 450 ℃, depicting the characteristic semiconductor behavior. Room temperature ferromagnetic behavior was observed in all the compositions. The value of saturation magnetization increased with the increase of A1 concentration in ZnMnO system referred to the gradual enhancement of free carriers.

Density of Electron States and Volume of Solution of Hydrogen in SiC Alloys

The new reactor concepts are characterized by higher efficiency, better utilization of nuclear fuel and nuclear waste minimization. This approach means that it is necessary to continue a continued research and test of new materials in order to apply them in new reactors. In this study, the authors fbcused on the analysis of SiC alloys because, due to their particular properties, this alloy can be used in high temperature conditions where the pure silicon, semiconductor material par excellence, is inadequate to support them.

Metal‐organic framework‐derived multifunctional photocatalysts

Metal‐organic framework(MOF)‐derived nanomaterials have attracted widespread attention,because the excellent features,such as high surface area,porosity and tunable properties are inherited from MOFs.Moreover,the derivatives avoid the poor conductivity and stability of MOFs.MOF‐derived nanomaterials can easily be regulated by a specific selection of metal nodes and organic linkers,resulting in multifunctionality in photocatalysis.MOF derivatives can be used not only as semiconductor photocatalysts,but also as co‐catalysts for photocatalytic hydrogen evolution,CO_(2) reduction,pollutants degradation,etc.This review focuses on the multifunctional applications of MOF derivatives in the field of photocatalysis.The researches in recent years are analyzed and summarized from the aspects of preparation,modification and application of MOF derivatives.At the end of the review,the development and challenges of MOF derivatives applied in photocatalysis in the future are put forward,in order to provide more references for further research in this field and bring new inspiration.