Fabricating GeO2 passivation layer by N20 plasma oxidation for Ge NMOSFETs application

In this paper, oxidation of Ge surface by N2O plasma is presented and experimentally demonstrated. Results show that 1.0-nm GeO2 is achieved after 120-s N20 plasma oxidation at 300 ℃. The GeO2/Ge interface is atomically smooth. The interface state density of Ge surface after N20 plasma passivation is about - 3 × 1011 cm-2.eV-1. With GeO2 passivation, the hysteresis of metal-oxide-semiconductor （MOS） capacitor with A1203 serving as gate dielectric is reduced to - 50 mV, compared with - 130 mV of the untreated one. The Fermi-level at GeO2/Ge interface is unpinned, and the surface potential is effectively modulated by the gate voltage.     

掺E~(3+)石英光纤中频率上转换的实验研究

首次报道了实验研究连续1064nm激光泵浦的掺Er~(3+)石英光纤中频率上转换过程.测量了Er~(3+)/GeO_2/SiO_2和Er~(3+)/Al_2O_3/GeO_2/SiO_2两种光纤发射的可见荧光谱,并用Er~(3+)离子的双光子吸收和受激态吸收过程解释了频率上转换现象.     

Investigation of a 4H-SiC metal-insulationsemiconductor structure with an A1203/SiO2 stacked dielectric

Atomic layer deposited （ALD） Al2O3/dry-oxidized ultrathin SiO2 films as a high-k gate dielectric grown on 8° off-axis 4H-SiC （0001） epitaxial wafers are investigated in this paper. The metal-insulation-semiconductor （MIS） capacitors, respectively with different gate dielectric stacks （Al2O3/SiO2, Al2O3, and SiO2） are fabricated and compared with each other. The I-V measurements show that the Al2O3/SiO2 stack has a high breakdown field （≥12 MV/cm） comparable to SiO2, and a relatively low gate leakage current of 1 × 10-7 A/cm2 at an electric field of 4 MV/cm comparable to Al2O3. The 1-MHz high frequency C-V measurements exhibit that the Al2O3/SiO2 stack has a smaller positive flat-band voltage shift and hysteresis voltage, indicating a less effective charge and slow-trap density near the interface.     

GeO2对Eu3+掺杂Bi2O3-B2O3-ZnO玻璃光谱性质的影响

用高温融熔法制备了Eu^3＋掺杂摩尔分数为1％的（60-X）Bi2O3-XGeO2-30B2O3-10ZnO（摩尔分数X=5,10,20,30）系统玻璃。测定了玻璃的差热分析曲线、发射光谱与激发光谱。从发射光谱与稀土Eu^3＋离子光学跃起矩阵元的特点,计算了Eu^3＋光学跃迁的参量Ω2与Ω1。结果显示强度参量Ω2与Ω4随着GeO2量的增加而增加,表明材料的对称性降低,Eu-O键强增加,共价性增加。玻璃的软化温度随GeO2组份的增加而提高。在GeO2摩尔分数达10％时．析晶起始温度与玻璃软化温度的差达最大,约146℃,表明该玻璃的热稳定性最好。     

Effect of alumina thickness on Al_2O_3/InP interface with post deposition annealing in oxygen ambient

In this paper, the effect of alumina thickness on Al2O3/InP interface with post deposition annealing （PDA） in the oxygen ambient is studied. Atomic layer deposited （ALD） Al2O3 films with four different thickness values （5 nm, 7 nm, 9 nm, 11 rim） are deposited on InP substrates. The capacitance-voltage （C-V） measurement shows a negative correlation between the alumina thickness and the frequency dispersion. The X-ray photoelectronspectroscopy （XPS） data present significant growth of indium-phosphorus oxide near the Al2O3/InP interface, which indicates serious oxidation of InP during the oxygen annealing. The hysteresis curve shows an optimum thickness of 7 nm after PDA in an oxygen ambient at 500 ℃ for 10 min. It is demonstrated that both sides of the interface are impacted by oxygen during post deposition annealing. It is suggested that the final state of the interface is of reduced positively charged defects on Al2O3 side and oxidized InP, which degrades the interface.     

Interfacial thermal resistance between high-density polyethylene （HDPE） and sapphire

To improve the thermal conductivity of polymeric composites, the numerous interfacial thermal resistance （ITR） inside is usually considered as a bottle neck, but the direct measurement of the ITR is hardly reported. In this paper, a sandwich structure which consists of transducer/high density polyethylene （HDPE）/sapphire is prepared to study the interface characteristics. Then, the ITRs between HDPE and sapphire of two samples with different HDPE thickness values are measured by time-domain thermoreflectance （TDTR） method and the results are -- 2 × 10-7 m2.K.W-1. Furthermore, a model is used to evaluate the importance of ITR for the thermal conductivity of composites. The model＇s analysis indicates that reducing the ITR is an effective way of improving the thermal conductivity of composites. These results will provide valuable guidance for the design and manufacture of polymer-based thermally conductive materials.     

Influence of strain distribution on the morphology evolution of a Ge/GeO_2 core/shell nanoparticle confined in ultrathin Al_2O_3 thin film by surface oxidation

The influence of strain distribution on morphology evolution of Ge/GeO2 core/shell nanoparticle confined in ultrathin Al2O3 thin film by surface oxidation is investigated. A finite-element simulation is performed to simulate the morphology evolution of the confined Ge/GeO2 core/shell nanoparticle under the influence of the local strain distribution. It indicates that the resultant oxidation-related morphology of Ge/GeO2 core/shell nanoparticle confined in ultrathin film is strongly dependent on the local strain distribution. On the other hand, the strain gradients applied on the confined GeO2 shell can be modified by the formation of polycrystalline GeO2 shell, which has potential application in tailoring the microstructure and morphology evolution of the Ge/GeO2 core/shell nanoparticle.     

含Ho~(3+)的GeO_2-B_2O_3-BaO-Na_2O-Al_2O_3锗酸盐玻璃的光谱与增益特性

用高温熔融法制备了不同Ho3+离子掺杂浓度65GeO2-12B2O-10BaO-10Na2O-3Al2O3-χHo2O3(χ=0.25,0.75,1.25mol%)锗酸盐玻璃。从吸收特性出发,应用McCumber理论计算了Ho3+离子能级5I8→5I7(~2.0μm)跃迁的吸收截面和5I7→5I8的受激发射截面。根据掺杂离子的浓度以及获得的吸收截面和受激发射截面得到Ho3+离子在此玻璃中的增益截面函数,从该函数可反映出材料的粒子数反转特性。获得的基本光学参数与其它掺杂的玻璃进行了比较,其吸收截面、发射截面和增益截面的最大值具有一定的优势。认为该玻璃在~2.0μm波段的中红外激光器中将有潜在的较大应用前景。     

The phase transition,hygroscopicity, and thermal expansion properties of Yb_2-xAl_xMo₃O₁₂

Materials with the formula Yb 2-xAlxMo3O12(x =0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 0.9, 1.0, 1.1, 1.3, 1.5, and 1.8) were synthesized and their structures, phase transitions, and hygroscopicity investigated using X-ray powder diffrac- tion, Raman spectroscopy, and thermal analysis. It is shown that Yb2-xAlxMo3O12 solid solutions crystallize in a single monoclinic phase for 1.7 ≤ x ≤ 2.0 and in a single orthorhombic phase for 0.0 ≤ x ≤ 0.4, and exhibit the characteristics of both monoclinic and orthorhombic structures outside these compositional ranges. The monoclinic to orthorhombic phase transition temperature of Al2Mo3O12 can be reduced by partial substitution of Al 3+ by Yb3+, and the Yb2-x AlxMo3O12 (0.0 < x ≤ 2.0) materials are hydrated at room temperature and contain two kinds of water species. One of these interacts strongly with and hinders the motions of the polyhedra, while the other does not. The partial substitution of Al3+ for Yb3+ in Yb2Mo3O12 decreases its hygroscopicity, and the linear thermal expansion co- efficients after complete removal of water species are measured to be 9.1×10 6 /K, 5.5×10 6 /K, 5.74×10 6 /K, and 9.5 × 10 6 /K for Yb1.8 Al0.2 (MoO4)3 , Yb1.6Al0.4 (MoO4 )3, Yb0.4 Al1.6 (MoO4)3 , and Yb 0.2Al1.8 (MoO4)3 , respectively.     

一种具有应用潜力的等离子体用绿色荧光粉(英文)

研究了绿色荧光粉Ca2GeO4∶Tb3+的真空紫外光谱性质,用172 nm激发荧光粉,其发射峰在549 nm,此绿色发光峰归属于Tb3+的5D4→7F5磁偶极跃迁,Tb3+离子的最佳摩尔分数x=0.05。激发光谱中147 nm和172 nm的激发强度分别是218 nm的1.5和1.7倍。因为在等离子体显示中激发光波长是147 nm和172nm,因此荧光粉在这两个波长的激发强度对荧光粉在等离子体显示中的应用至关重要。Al3+的共掺杂可使荧光粉的发光强度增强2倍,因此,Ca2GeO4∶Tb3+是一种具有应用潜力的等离子体显示用绿色荧光粉。     

Influence of annealing temperature on passivation performance of thermal atomic layer deposition Al_2O_3 films

Chemical and field-effect passivation of atomic layer deposition （ALD） Al2O3 films are investigated, mainly by corona charging measurement. The interface structure and material properties are characterized by transmission electron microscopy （TEM） and X-ray photoelectron spectroscopy （XPS）, respectively. Passivation performance is improved remarkably by annealing at temperatures of 450 ℃ and 500 ℃, while the improvement is quite weak at 600 ℃, which can be attributed to the poor quality of chemical passivation. An increase of fixed negative charge density in the films during annealing can be explained by the Al2O3/Si interface structural change. The Al–OH groups play an important role in chemical passivation, and the Al–OH concentration in an as-deposited film subsequently determines the passivation quality of that film when it is annealed, to a certain degree.     

CH4、CO2、O2制合成气用Ni-Ce/Al2O3催化剂的XPS研究

用XPS表征浸渍法制备的Ni-Ce／Al2O3催化剂,并与活性评价结果相关联,研究了添加Ce对催化剂性能的影响,探讨了催化剂失活的原因。结果表明,稀土Ce在反应过程中存在着部分还原变价过程(Ce^4 e→Ce^2 ),Ce^3 能够迁移至A12O3晶格,增强载体Al2O3的抗烧结能力,提高催化剂的稳定性;Ni-Ce/Al2O3催化剂表面的Ni和Ce在反应过程中向体相迁移,以及Ni晶粒的烧结是造成催化剂活性逐步下降的主要原因。     

F4-TCNQ concentration dependence of the current-voltage characteristics in the Au/P3HT：PCBM：F4-TCNQ/n-Si （MPS） Schottky barrier diode

In this study, we investigate some main electrical parameters of the gold/poly（3-hexylthiophene）：[6,6]-phenyl C61 bu- tyric acid methyl ester：2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane/n-type silicon （Au/P3HT：PCBM：F4-TCNQ/n- Si） metal-polymer-semiconductor （MPS） Schottky barrier diode （SBD） in terms of the effects of F4-TCNQ concentration （0%, 1%, and 2%）. F4-TCNQ-doped P3HT：PCBM is fabricated to figure out the p-type doping effect on the device per- formance. The main electrical parameters, such as ideality factor （n）, barrier height （ФB0）, series resistance （Rs）, shunt resistance （Rsh）, and density of interface states （Nss） are determined from the forward and reverse bias current-voltage （l-V） characteristics in the dark and at room temperature. The values of n, Rs, ФB0, and Nss are significantly reduced by using the 1% F4-TCNQ doping in P3HT：PCBM：F4-TCNQ organic blend layer, additionally, the carrier mobility and current are increased by the soft （1%） doping. The most ideal values of electrical parameters are obtained for 1% F4-TCNQ used diode. On the other hand, the carrier mobility and current for the hard doping （2%） become far away from the ideal diode values due to the unbalanced generation of holes/electrons and doping-induced disproportion when compared with 1% F4-TCNQ doping. These results show that the electrical properties of MPS SBDs strongly depend on the F4-TCNQ doping and doping concentration of interfacial P3HT：PCBM：F4-TCNQ organic layer. Moreover, the soft F4-TCNQ dop- ing concentration （1%） in P3HT：PCBM：F4-TCNQ organic layer significantly improves the electrical characteristics of the Au/P3HT：PCBM：F4-TCNQ/n-Si （MPS） SBDs which enables the fabricating of high-quality electronic and optoelectronic devices.     

Evidence of GeO volatilization and its effect on the characteristics of HfO2 grown on Ge substrate

HfO₂ films are deposited by atomic layer deposition (ALD) using tetrakis ethylmethylamino hafnium (TEMAH) as the hafnium precursor, while O₃ or H₂O is used as the oxygen precursor. After annealing at 500℃ in nitrogen, the thickness of Ge oxide's interfacial layer decreases, and the presence of GeO is observed at the H₂O-based HfO₂ interface due to GeO volatilization, while it is not observed for the O₃-based HfO₂. The difference is attributed to the residue hydroxyl groups or H₂O molecules in H₂O-based HfO₂ hydrolyzing GeO₂ and forming GeO, whereas GeO is only formed by the typical reaction mechanism between GeO₂ and the Ge substrate for O₃-based HfO₂ after annealing. The volatilization of GeO deteriorates the characteristics of the high-κ films after annealing, which has effects on the variation of valence band offset and the C–V characteristics of HfO₂/Ge after annealing. The results are confirmed by X-ray photoelectron spectroscopy (XPS) and electrical measurements.     

Ba2+掺杂对Sr3Al2O6:Eu2+红色荧光粉发光性能的影响

采用高温固相法合成了(Sr1-x-yBax)3Al2O6∶3yEu2+红色荧光材料,通过XRD、荧光光谱和热稳定性测试分析,分别研究了Eu2+、Ba2+掺杂对样品的晶体结构、发光性能和热稳定性的影响。XRD测试结果表明,在1 200℃保温3 h条件下合成了具有立方晶体结构、空间群为Pa3的Sr3Al2O6纯相样品,Eu2+、Ba2+的掺入并没有改变其基质晶格的结构类型。荧光光谱分析表明,Eu2+的摩尔分数为4%时,(Sr0.98-yBa0.02)3Al2O6∶3yEu2+样品的发射峰最强,Ba2+的掺入使样品的发射峰发生红移而发射强度降低,且随Ba2+浓度的增加红移越发明显。此外,Ba2+的掺杂提高了Sr3Al2O6∶Eu2+样品的热稳定性。     

若干钠锗酸盐晶体和熔体的温致结构变化及其锗配位数的拉曼光谱研究

本文测定了Na4GeO4、Na2GeO3、Na2Ge4O9和Na4Ge9O20等晶体从273K到1413K升温及熔体的拉曼光谱,结合分析金红石型GeO2的相关结构和光谱,研究了其微结构单元在升温过程中的变化、熔体中的形态和锗的氧配位数及其温致变化。Na4GeO4和Na2GeO3晶体结构单元为GeO4四面体,在升温过程及其熔体中锗维持四配位。Na2Ge4O9和Na4Ge9O20晶体结构单元为GeO4四面体和GeO6八面体共存,升温过程中,GeO6八面体将发生结构转变,在熔融状态全部转变为GeO4四面体,并产生与钠离子等摩尔分数的非桥氧,在熔体中锗的氧配位数为4。研究还表明,桥氧的对称弯曲振动模可以反映不同微结构单元间的连接,并且随着温致结构的变化而产生特征性的变化。     

Subsolidus phase relation in the Bi2O3-Fe203-La2O3 system

Bismuth-containing semiconductor material is a hot topic in photocatalysts because of its effective absorption under the visible light. In this paper, we expect to explore a new bismuth-based photocatalyst by studying the subsolidus phase relations of the Bi2O3-Fe2O3-La2O3 system. The X-ray diffraction data shows that in this ternary system the ternary compound does not exist, while seven binary compounds （including one solid solution series Bi1-xLaxO1.5 with 0.167 〈 x 〈 0.339） are obtained and eight compatibility triangles are determined.     

Synergistic effects of total ionizing dose on single event upset sensitivity in static random access memory under proton irradiation

Nitrogen plasma passivation （NPP） on （111） germanium （Ge） was studied in terms of the interface trap density, roughness, and interfacial layer thickness using plasma-enhanced chemical vapor deposition （PECVD）. The results show that NPP not only reduces the interface states, but also improves the surface roughness of Ge, which is beneficial for suppressing the channel scattering at both low and high field regions of Ge MOSFETs. However, the interracial layer thickness is also increased by the NPP treatment, which will impact the equivalent oxide thickness （EOT） scaling and thus degrade the device performance gain from the improvement of the surface morphology and the interface passivation. To obtain better device performance of Ge MOSFETs, suppressing the interfacial layer regrowth as well as a trade-off with reducing the interface states and roughness should be considered carefully when using the NPP process.     

Ti：Al2O3晶体中Ti^3＋离子的电子顺磁共振研究

通过对Ｔｉ：Ａｌ２Ｏ３晶体的不同取向的电子顺磁共振（ＥＰＲ）研究，认为在９３Ｋ温度下观测到的ｇ＝２．００的强烈各向异性的共振线是来自于Ｔｉ：Ａｌ２Ｏ３晶体中的Ｔｉ３＋离子２Ｔ２ｇ能态的中间能级１Ｅ１／２的顺磁共振吸收。而室温下观察到的ｇ≈２．００的吸收线是由Ｔｉ３＋离子２Ｔ２ｇ能态上能级２Ａ１的共振吸收产生的。由晶体场理论进行的计算与上述结果基本符合。