EXPERIMENTS OF MeV ION BEAM INDUCED ATOMIC MIXING

An experimental apparatus for studies of MeV ion beam modification of materials has been established on a 3 MV tandem accelerator at Fudan university. A system of X-Y electrostatic scanning implantation of MeV heavy ions and in situ Rutherford. backscattering analysis was included in it. The uniformity of scanning implantation was checked by the RBS measurement of a Si wafer implanted with 1 MeV Au ions. MeV ion beam mixing of Au/Si, Au/Ge and Ag/Si systems was preliminarily studied. The samples were irradiated by certain fluences of 1 MeV Ag ions at room temperature. The mixed layers were analyzed in situ using the glancing RBS technique with 2 MeV 4He+ ions. For Au/Si system, a uniformly mixed layer with a defined composition is obtained, and the intermixing is much less for Ag/Si system than for Au/Si system.     

原材料Gd对Gd-Si-Ge合金巨磁热效应影响的研究

采用国产钆制作Gd—Si—Ge合金，测量H-M曲线，计算磁熵变(-△Sm)判断其磁热效应。发现采用商业级钆配制合金时，由于杂质抑制了材料的一级相变，未发现巨磁热效应。经提纯后的钆尽管没有Ames实验室的纯度高，但配制的合金具有典型的一级相变，-△Sm值基本上达到Ames实验室报道的数据，而且居里点有所提高。     

红外非线性晶体Na2Ge2Se5非线性变频模拟计算

对红外非线性光学晶体Na2Ge2Se5的非线性性质进行了研究。计算了在主平面内倍频调谐曲线,0.946μm、1.064μm、1.1319μm泵浦情况下的倍频空间调谐曲线以及和频产生0.589μm激光的匹配曲线,并对计算结果进行了分析比较。所得结果可为Na2Ge2Se5晶体用于特定波长激光器,设计新波段提供理论依据。     

Positioning and doping effects on quantum dot multi‐junction solar cell performance

The positioning of InAs quantum dot (QD) layers in a triple‐junction GaInP/Ga(In)As/Ge solar cell is studied using numerical modeling techniques. An effective medium is used to describe the absorption characteristics and carrier dynamics in each QD layer. The effects of incorporating 110 layers in the emitter, base layers, as well as between these regions of the middle sub‐cell are analyzed with current–voltage characteristics and energy band diagrams. The cell with QDs positioned between the emitter and base demonstrated an efficiency of 31% under 1 sun illumination at room temperature. The performance was then increased to 31.3% by optimizing the QD region doping. Copyright © 2014 John Wiley & Sons, Ltd.     

Growth-direction-dependent characteristics of Ge-on-insulator by Si–Ge mixing triggered melting growth

The lateral liquid-phase epitaxy of Ge-on-insulator (GOI) using Si seeds has been investigated as a function of the Si-seed orientation and the growth direction. Giant single-crystalline GOI structures with ∼200 μm length are obtained using Si(1 0 0), (1 1 0), and (1 1 1) seeds. The very long growth is explained on the basis of the solidification temperature gradient due to Si-Ge mixing around the seeding area and the thermal gradient due to the latent heat around the solid/liquid interface at the growth front. In addition, growth with rotating crystal orientations is observed for samples with several growth directions. The rotating growth is explained on the basis of the bonding strength between lattice planes at the growth front. This rotating growth does not occur in any direction for (1 0 0) orientated seeds. Based on this finding the mesh-patterned GOI growth with a large area (250 μm × 500 μm) is demonstrated.     

X-ray microdiffraction investigation of crystallinity and strain relaxation in Ge thin lines selectively grown on Si(0 0 1) substrates

We used X-ray microdiffraction (XRMD) to investigate the crystallinity and strain relaxation of Ge thin lines with widths of 100, 200, 500 and 1000 nm selectively grown on Si(0 0 1) substrates using a patterned SiO₂ mask by chemical vapor deposition. The variations of the strain relaxation in the line and width directions were also investigated in Ge thin lines with a width of 100 nm. After growth, crystal domains with very small tilt angles were detected in Ge lines with all four line widths. The tilt angle range was larger in thinner Ge lines. After annealing at 700 °C, the formation of a single, large domain with a specific tilt angle was detected by XRMD for Ge thin lines with widths of 100 and 200 nm. These experimental results reflect the effects of SiO₂ side walls around the Ge thin lines on crystallinity and strain relaxation of Ge.     

0.28-2.80 MeV质子辐射对空间实用GaInP/GaAs/Ge多结太阳电池性能的影响

用0.28、0.62和2.80 MeV质子束模拟空间辐射对国产MOCVD方法制备的GaInP/GaAs/Ge多结电池进行质子辐射效应研究.辐照注量为1×1012 cm-2.对电池的辐射效应用I-V特性和光谱响应测试进行分析.结果表明:随质子辐照能量的增加,太阳电池性能参数Isc,Voc,Pmax和光谱响应的衰降幅度均减小,0.28MeV质子辐照引起电池性能衰降最显著;低能质子辐照引起中间GaAs电池光谱响应衰降更明显.     

不同气体退火La_2O_3栅介质Ge MOS电容的电特性

采用电子束蒸发方法,在Ge衬底上淀积La_2O_3高k栅介质,研究了O_2、NO、NH_3和N_2不同气体退火对MOS电容电特性的影响。测量了器件的C-V和I-V特性,并进行了高场应力实验。结果表明La_2O_3在N_2气氛中退火后,由于形成稳定的LaGeO_x而有效地降低了Q_(ox)和D_(it),从而获得低的栅极漏电流,同时获得较高的栅介质介电常数(18)。     

Enhanced efficiency of hematite photoanode for water splitting with the doping of Ge

Ge doped α-Fe₂O₃ nanowires are synthesized through a hydrothermal procedure with GeO₂ as a precursor and investigated as photoanodes for water splitting. The content of Ge in the photoanode rises with the increase of the amount of GeO₂ in the precursor solution. A proper amount of Ge facilities the preferred oriented growth of the (110) plane of α-Fe₂O₃, while excessive Ge hinders the growth of α-Fe₂O₃ crystals. The doping of Ge increases the absorption efficiency and decreases the recombining rate of the photogenerated electrons and holes. Ge also improves the density and transfer rate of the charge carriers in the photoanode. Ge doped α-Fe₂O₃ photoanode exhibits a highest photocurrent density of 0.92 mA cm^?2 at 1.23 V vs. reversible hydrogen electrode under AM 1.5 G simulated sunlight, which is nearly twice of that obtained by pure α-Fe₂O₃ under the same condition.     

提高置换渣锗品位的工业实践研究

丹霞冶炼厂加压浸出液富集分离镓锗的工业生产中：镓锗富集物中锗的品位波动较大,中和渣中锗含量高,严重制约了锗的高效回收。本文结合丹霞冶炼厂生产实践中遇到的问题,从工艺制度、设备优化二个方面进行了系统的分析和讨论,为丹霞冶炼厂锗富集分离工业生产优化提供了指导。