Thermal experiment of silicon PIN detector

The experiment of this paper is the thermal test of the leakage current of silicon PIN detector.Raising temperature may cause the detector to increase leakage current,decrease depletion and increase noise.Three samples are used in the experiment.One (called △E) is the sample of 100 tan in thickness.The other two (called E1 and E2) are stacks of five detectors of 1000 μm in thickness.All of them are 12 mm in diameter.The experiment has been done for 21 hours and with power on continuously.The samples have undergone more than 60 ℃ for about one hour.They are not degenerated when back to the room temperature.The depletion rate is temperature and bias voltage related.With the circuit of the experiment and temperature at 35 ℃,△E is still depleted while E1 and E2 are 94.9% and 99.7% depleted respectively.The noises of the samples can be derived from the values at room temperature and the thermal dependence of the leakage currents.With the addition of the noise of the pre-amplifier,the noises of E1,E2 and AE at 24 ℃ are 16.4,16.3,and 10.5 keV (FWHM) respectively while at 35 ℃ are about 33.6,33.1,and 20.6 keV (FWHM) respectively.     

Mechanical Properties and Anisotropy in PbWO4 Single Crystal

The mechanical properties of PbWO4 （PWO） crystals grown by the vertical Bridgman method are systematically investigated using the microindentation technique. In the present work, the Vickers microhardness Hν, fracture toughness Kc, yield strength σy and friability index Bi of PbWO4 crystals are measured. The Vickers microhardness Hν on the （100） wafer is about 140 MPa, which means that PWO is a little soft＇＇ scintillator. The anisotropy of mechanical properties is also investigated under a steady load of 0.5 kg. The （100） wafer of the crystal exhibits combined mechanical properties more excellent than those of （111） and （001） wafers, and the values of Kc, σy, and Bi are 0.538 MPa＆#12539;m1/2, 51.11 kg/mm2 and 284.96 νm-1/2, respectively.     

High-Average-Power Nanosecond Quasi-Phase-Matched Single-Pass Optical Parametric Generator in Periodically Poled Lithium Niobate

A pulsed nanosecond optical parametric generator (OPG) in periodically poled lithium niobate (PPLN) crysal is presented. The pump laser is an acousto-optically Q-switched Nd:YVO4 laser with the maximum average power of 6.58 W. When the repetition rate is 50kHz and the pulse width of the pump source is 80ns, the maximum average total output power of the single-pass PPLN OPG is about 1.9 W, which includes 1.322 W of 1.536μm signal radiation. The length of the PPLN crystal is only 38.7mm (at room temperature) with a grating period of 28.93μm (at room temperature). The 1.502-1.536μm signal radiation and 3.652-3.465μm idler radiation are obtained by adjusting the PPLN crystal temperature from 155℃ to 250℃.     

Growth and Characterization of a Kind of Nitrogen-Rich Niobium Nitride for Bolometer Applications at Terahertz Frequencies

Niobium is sputtered onto a single crystalline silicon substrate in N2：Ar=4：1 gas mixture at the total pressure of 2 Pa. The temperature coefficient of resistance of the sample is about 0.5% at 30OK, and up to 7% at 77K, indicating the possibility of using it to make room-temperature bolometers with performances better than those based on Pt, Bi, or Nb. For a 60-nm-thick sample, the rms surface roughness is 0.45nm over an area of 2 μm × 2 μm. Analyses based on x-ray diffraction and x-ray photoelectronic spectroscopy indicate that the samples are Nb5N6 thin films in which there is a combination of Nb^3＋ and Nb^5＋, or Nb^4＋.     

High-strain InGaAs/GaAs quantum well grown by MOCVD

High-strain InGaAs/GaAs quantum wells （QWs） are grown by low-pressure metal-organic chemical vapor deposition （LP-MOCVD）. Photoluminescence （PL） at room temperature is applied for evaluation of the optical property. The influence of growth temperature, V/III ratio, and growth rate on PL characteristic are investigated. It is found that the growth temperature and V/III ratio have strong effects on the peak wavelength and PL intensity. The full-width at half-maximum （FWHM） of PL peak increases with higher growth rate of InGaAs layer. The FWHM of the PL peak located at 1039 nm is 20.1 meV, which grows at 600 ℃ with V/ III ratio of 42.7 and growth rate of 0.96 μm/h.     

Photoluminescence Characterization of Nanocrystalline ZnO Array

High-density and uniform well-aligned ZnO sub-micron rods are synthesized on the silicon substrate over a large area. The morphology and structure of the ZnO sub-micron rods are investigated by x-ray diffraction, transmission electron microscopy and Raman spectra. It is found that the ZnO sub-micron rods are of high crystal quality with the diameter in the range of 400-600 nm and the length of several micrometres long. The optical properties were studied by photoluminescence spectra. The results show that the intensity of the ultraviolet emission at 3.3eV is rather high, meanwhile the deep level transition centred at about 2.38eV is weak. The free exciton emission could a/so be observed at low temperature, which implies the high optical quality of the ZnO sub-micron rods.This growth technique provides one effective way to fabricate the high crystal quality ZnO nanowires array, which is very important for potential applications in the new-type optoelectronic nanodevices.     

Thermal experiment of silicon PIN detector

The experiment of this paper is the thermal test of the leakage current of silicon PIN detector. Raising temperature may cause the detector to increase leakage current, decrease depletion and increase noise. Three samples are used in the experiment. One (called ΔE) is the sample of 100 μm in thickness. The other two (called E₁ and E₂) are stacks of five detectors of 1000 μm in thickness. All of them are 12 mm in diameter. The experiment has been done for 21 hours and with power on continuously. The samples have undergone more than 60℃ for about one hour. They are not degenerated when back to the room temperature. The depletion rate is temperature and bias voltage related. With the circuit of the experiment and temperature at 35℃, ΔE is still depleted while E₁ and E₂ are 94.9% and 99.7% depleted respectively. The noises of the samples can be derived from the values at room temperature and the thermal dependence of the leakage currents. With the addition of the noise of the pre-amplifier, the noises of E₁, E₂ and ΔE at 24℃ are 16.4, 16.3, and 10.5 keV (FWHM) respectively while at 35℃ are about 33.6, 33.1, and 20.6 keV (FWHM) respectively.     

Electroluminescence and Photoluminescence from Scored Si—Rich SiO2 Film／p—Si Structure

Electroluminescence(EL)is observed from the Au/Si-rich SiO2 film/p-Si diodes,in which the Si-rich SiO2 films are scroed deliberately by a diamond tip.The EL intensity of the scroed diode annelaed at 800℃ is about 6 times of that of the unscored counterpart,The EL sectrum of the usscored diode could be decomposed into two Gaussian luminescence bands with peaks at about 1.83 and 2.23eV,while for the EL spectrum of the scored diode,an additional Gaussian band at about 3.0eV appears,and the 1.83-eV peak increases significantly in intensity,The photoluminescence(PL) spectrum of an unscored Si-rich SiO2 film has only one band peaking at about 1.48eV,whereas the Pl spectrum of the scored one has two bands at about 1.48 and 1.97eV.We consider that the high-density defect regions produced by the scoring provide new luminescence centres and become some types of nonradiative centres in the Si oxide layer,which thus result in changes of the EL and PL spectra.     

K_2S-activated carbons developed from coal and their methane adsorption behaviors

The main purpose of this work is to prepare various activated carbons by K2S activation of coal with size fractions of 60-80 meshes, and investigate the microporosity development and corresponding methane storage capacities. Raw coal is mixed with K2S powder, and then heated at 750 ℃-900 ℃ for 30 min-150 min in N2 atmosphere to produce the adsorbents. The texture and surface morphology are characterized by a N2 adsorption/desorption isotherm at 77 K and scanning electron microscopy （SEM）. The chemical properties of carbons are confirmed by ultimate analysis. The crystal structure and degree of graphitization are tested by X-ray diffraction and Raman spectra. The relationship between sulfur content and the specific surface area of the adsorbents is also determined. K2S activation is helps to bring about better development of pore texture. These adsorbents are microporous materials with textural parameters increasing in a range of specific surface area 72.27 m2/g-657.7 m2/g and micropore volume 0.035 cm3/g-0.334 cm3/g. The ability of activated carbons to adsorb methane is measured at 298 K and at pressures up to 5.0 MPa by a volumetric method. The Langmuir model fits the experimental data well. It is concluded that the high specific surface area and micropore volume of activated carbons do determine methane adsorption capacity. The adsorbents obtained at 800 ℃ for 90 min with K2S/raw coal mass ratios of 1.0 and 1.2 show the highest methane adsorption capacities amounting to 106.98 mg/g and 106.17 mg/g, respectively.     

Structures and magnetic behaviours of TiO2-Mn-TiO2 multilayers

The TiO2-Mn-TiO2 multilayers are successfully grown on glass and silicon substrates by alternately using radio frequency reactive magnetron sputtering and direct current magnetron sputtering. The structures and the magnetic behaviours of these films are characterised with x-ray diffraction, transmission electron microscope (TEM), vibrating sample magnetometer, and superconducting quantum interference device (SQUID). It is shown that the multi-film consists of a mixture of anatase and rutile TiO2 with an embedded Mn nano-film. It is found that there are two turning points from ferromagnetic phase to antiferromagnetic phase. One is at 42 K attributed to interface coupling between ferromagnetic Mn3O4 and antiferromagnetic Mn2O3, and the other is at 97 K owing to the interface coupling between ferromagnetic Mn and antiferromagnetic MnO. The samples are shown to have ferromagnetic behaviours at room temperature from hysteresis in the M-H loops, and their ferromagnetism is found to vary with the thickness of Mn nano-film. Moreover, the Mn nano-film has a critical thickness of about 18.5 nm, which makes the coercivity of the multi-film reach a maximum of about 3.965×10 2 T.     

溶剂热再结晶合成由纳米颗粒自组装成的一维CdS纳米棒

采用两种不同的溶剂热路径合成出了不同形貌和尺寸的CdS纳米晶, 一种是以无水乙二胺(en) 为溶剂, CdCl₂·2.5H₂O和硫脲(H₂NCSH₂N) 为镉源和硫源, 在不同反应温度(160 ℃-220 ℃ 下制备出了CdS纳米晶, 讨论温度对CdS纳米晶生长的影响; 另一种是以en为溶剂, 将在160 ℃下合成的产物在200 ℃下原位再结晶生长2-8 h, 分析原位生长时间对CdS纳米晶生长的影响. 通过X射线衍射(XRD)、 扫描电子电镜(SEM) 和透射电子电镜(TEM) 等表征产物的物相、 形貌和微结构, 分析可知: 两种路线合成的产物均为六方相CdS; 当温度为160 ℃时, 产物形貌为纳米颗粒状, 当温度高于160 ℃时, 产物为CdS纳米棒状; 同时, 在200 ℃下原位再结晶生长不同时间后发现产物形貌由纳米颗粒转变为纳米棒, 通过场发射扫描电镜(HRTEM) 分析可知: 纳米棒是由零维纳米颗粒自组装而成. 最后, 讨论了影响产物CdS纳米晶形貌转变的因素和纳米棒的生长机理.     

TiO2/Al2O3薄膜的原子层沉积和光学性能分析

采用原子层沉积技术在熔石英和BK7玻璃基片上镀制了TiO2/Al2O3薄膜,沉积温度分别为110℃和280℃。利用X射线粉末衍射仪对膜层微观结构进行了分析研究,并在激光损伤平台上进行了抗激光损伤阈值测量。采用Nomarski微分干涉差显微镜和原子力显微镜对激光损伤后的形貌进行了观察分析。结果表明,采用原子层沉积技术镀制的TiO2/Al2O3增透膜的厚度均匀性较好,Φ50 mm样品的膜层厚度均匀性优于99%;光谱增透效果显著,在1 064 nm处的透过率〉99.8%;在熔石英和BK7基片上,TiO2/Al2O3薄膜在110℃时的激光损伤阈值分别为（6.73±0.47）J/cm2和（6.5±0.46）J/cm2,明显高于在280℃时的损伤阈值。     

新型电子俘获型光存储材料Sr2SnO4:Sb3+的发光性能研究

采用高温固相法在1300℃的温度获得了一种新型电子俘获型光存储材料 Sr₂SnO₄:Sb³⁺. 结果表明: 208 nm (Sb³⁺ 的¹S₀→¹P₁)和265 nm (¹S₀→³P₁)的紫外光是Sr₂SnO₄:Sb³⁺ 的最有效信息写入光源; 其发射是覆盖400---700 nm的宽带(³P_0,1→^XXS₀), 肉眼可看到淡黄色白光, 色坐标为(0.341, 0.395). 热释光谱研究结果表明: Sr₂SnO₄:Sb³⁺ 有分别位于39℃, 124℃, 193℃和310℃的四个热释峰. 其中, 39~℃的热释峰强度很低, 因而Sr₂SnO₄:Sb³⁺ 只具有不到140 s的微弱余辉. 而310℃的高温热释峰在空置1天后, 仍能保持约45.6%的初始强度, 并对980 nm的红外光有很好的红外上转换光激励响应. 因此, Sr₂SnO₄:Sb³⁺ 是一种具有一定的信息存储应用潜力的新型光存储发光材料.     

高温退火处理下SiNx薄膜组成及键合结构变化

采用等离子增强化学气相沉积法, 以氨气和硅烷为反应气体, p型单晶硅为衬底, 低温下(200 ℃)制备了非化学计量比氮化硅(SiN_x)薄膜. 在N₂氛围中, 于500–1100 ℃范围内对薄膜进行热退火处理. 室温下分别使用Fourier变换红外吸收(FTIR)光谱技术和X射线光电子能谱(XPS)技术测量未退火以及退火处理后SiN_x薄膜的Si–N, Si–H, N–H键键合结构和Si 2p, N 1s电子结合能以及薄膜内N和Si原子含量比值R的变化. 详细讨论了不同温度退火处理下SiN_x薄膜的FTIR和XPS光谱演化同薄膜内Si, N, H原子间键合方式变化之间的关系. 通过分析FTIR和XPS光谱发现退火温度低于800 ℃时, SiN_x薄膜内Si–H和N–H键断裂后主要形成Si–N键; 当退火温度高于800 ℃时薄膜内Si–H和N–H键断裂利于N元素逸出和Si纳米粒子的形成; 当退火温度达到1100 ℃时N₂与SiN_x薄膜产生化学反应导致薄膜内N和Si原子含量比值R增加. 这些结果有助于控制高温下SiN_x薄膜可能产生的化学反应和优化SiN_x薄膜内的Si纳米粒子制备参数. 关键词： x薄膜')" href="#">SiN_x薄膜 Fourier变换红外吸收光谱 X射线光电子能谱 键合结构     

Ru(0001) 表面BaO吸附层的原子结构和氮分子的吸附性质

采用密度泛函理论研究了Ru(0001) /BaO表面的原子层结构和氮分子的吸附性质. 研究结果表明, 在低覆盖度下氧化钡倾向于以相同的构型形成Ru(0001) 表面原子层. 在此构型中, 氧原子位于表面p(1× 1) 结构的hcp谷位, 而钡原子则位于同一p(1× 1) 结构的顶位附近. 钌氧键键长等于0.209 nm, 比EXAFS的实验值大0.018 nm. 在Ru(0001) /BaO表面氮分子倾向吸附于钡原子附近. 相应位置的氮分子吸附能位于0.70到0.87 eV之间, 大于氧原子附近的氮分子吸附能. 钡原子附近的钌原子对氮分子具有更强的活化性能. 相应位置的氮分子拉伸振动频率等于1946 cm^{- 1}, 比氧原子附近的最大分子振动频率小约130 cm^-1. Ru(0001) /BaO表面氮分子键强度介于清洁Ru(0001) 和Ru(0001) /Ba表面之间. Ru(0001)/BaO表面不同位置的氮分子吸附性质差异是由钡和氧原子化学性质不同造成的. 表面钡原子的作用能够减少吸附氮分子的σ^*轨道电子密度, 增加π^*轨道电子密度, 从而增强氮分子和钌原子间的轨道杂化作用, 弱化氮分子键.     

SiO2/Si衬底上石墨烯的制备与结构表征

在分子束外延(MBE)设备中,利用直接沉积C原子的方法在覆盖有SiO₂的Si衬底(SiO₂/Si)上生长石墨烯,并通过Raman光谱和近边X射线吸收精细结构谱等实验技术对不同衬底温度(500℃,600℃,700℃,900℃,1100℃,1200℃)生长的薄膜进行结构表征.实验结果表明,在衬底温度较低时生长的薄膜是无定形碳,在衬底温度高于700℃时薄膜具有石墨烯的特征,而且石墨烯的结晶质量随着衬底温度的升高而改善,但过高的衬底温度会使石墨烯质量降低.衬底温度为1100℃时结晶质量最好.衬底温度较低时C原子活性较低,难以形成有序的C-sp²六方环.而衬底温度过高时(1200℃),衬底表面部分SiO₂分解,C原子与表面的Si原子或者O原子结合而阻止石墨烯的形成,并产生表面缺陷导致石墨烯结晶变差.     

Influence of Zr(50)Cu(50) thin film metallic glass as buffer layer on the structural and optoelectrical properties of AZO films

Aluminum-doped ZnO(AZO) thin films with thin film metallic glass of Zr(50)Cu(50) as buffer are prepared on glass substrates by the pulsed laser deposition. The influence of buffer thickness and substrate temperature on structural, optical, and electrical properties of AZO thin film are investigated. Increasing the thickness of buffer layer and substrate temperature can both promote the transformation of AZO from amorphous to crystalline structure, while they show(100)and(002) unique preferential orientations, respectively. After inserting Zr(50)Cu(50) layer between the glass substrate and AZO film, the sheet resistance and visible transmittance decrease, but the infrared transmittance increases. With substrate temperature increasing from 25℃ to 520℃, the sheet resistance of AZO(100 nm)/Zr(50)Cu(50)(4 nm) film first increases and then decreases, and the infrared transmittance is improved. The AZO(100 nm)/Zr(50)Cu(50)(4 nm) film deposited at a substrate temperature of 360℃ exhibits a low sheet resistance of 26.7 ?/, high transmittance of 82.1% in the visible light region, 81.6% in near-infrared region, and low surface roughness of 0.85 nm, which are useful properties for their potential applications in tandem solar cell and infrared technology.     

WDXRF和FTIR对古滇国遗址出土陶器的初步分析

利用波长色散型X射线荧光光谱（WDXRF）和傅里叶变换红外光谱（FTIR）对环抚仙湖分布的澄江学山、金莲山和江川光坟头3个古滇国遗址出土的陶器从化学、结构组成以及烧成温度3方面进行了初步分析.WDXRF主次量元素分析结果表明,各遗址同类陶器（尤其是红陶）的基本制陶原料具有相似性,黑（褐）陶中添加的助熔剂含量明显高于红陶.FTIR分析结果显示同类陶器中包含的矿物具有一致性,红陶中含有石英和疑似铁矿物,黑（褐）陶中则都添加了大量的碳酸盐矿物.基于FTIR结果还对两类陶器的烧成温度做出了初步判断,估计黑（褐）陶在600-700℃,红陶在800℃左右.黑（褐）陶中较高含量的助熔剂可能在降低烧成温度方面起到了重要作用.以上初步分析表明,3个遗址出土的同类陶器在原料选择和烧成温度方面具有相似处,遗址间可能存在密切的联系.     

Yb^3＋：Y2O3超细粉体的低温燃烧法合成及发光性能

以稀土硝酸盐和尿素（摩尔分数为1∶3）为原料,采用低温燃烧法在点火温度为600℃,热处理温度为1 100℃,热处理时间为1 h条件下制备了Yb3＋∶Y2O3超细粉体。利用X射线粉末衍射仪（XRD）、扫描电子显微镜（SEM）和荧光光谱仪（FS）对粉体进行了表征。研究了点火温度、燃料用量和热处理温度对粉体性能的影响。实验结果表明：所制备的Yb3＋∶Y2O3超细粉体的粒径为15～30 nm,颗粒分散性较好,无明显团聚,且粉体的发光性能良好,发射峰位于976,1 030和1 075 nm,适合于制备Yb3＋∶Y2O3透明陶瓷。     

一个单滑移取向铜单晶体疲劳位错结构的热稳定性研究

利用扫描电镜电子通道衬度(SEM-ECC)技术观察研究了[4 18 41]单滑移取向铜单晶体在不同塑性应变幅下的疲劳饱和位错结构及其在不同温度等时退火条件下的热稳定性. 结果表明, 在退火温度为300 °C时, 疲劳位错结构(如脉络结构、驻留滑移带PSB楼梯结构、PSB胞结构和迷宫结构等)均发生了明显回复. 当退火温度高于500 °C, 上述这些疲劳位错结构基本消失, 均发生了明显的再结晶现象, 并大都伴随有退火孪晶的形成. 分析认为, 再结晶的发生和退火孪晶的出现不仅与退火温度和外加塑性应变幅有关, 还与累积循环塑性应变量有着密切的关系.