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141.
Orientation control of epitaxial Ge thin films growth on SrTiO3 (100) by ultrahigh vacuum sputtering
Wensheng Deng Ming Yang Jianwei ChaiTen It Wong Anyan DuChee Mang Ng Yuanping Feng Shijie Wang 《Thin solid films》2012,520(15):4880-4883
We report the orientation control of crystalline Ge (111) and Ge (001) growth on SrTiO3 (100) substrate by adjusting the temperature of substrate. It is found that the substrate temperature plays an important role for the formation of crystalline Ge with different surface orientations and interfacial chemical configuration during the sputtering process. At 500 °C, Ge (111) with good crystalline quality is formed, while Ge (001) is preferably grown on SrTiO3 substrate at 650 °C. Our results show the possibility of manipulating the surface orientations during Ge growth on SrTiO3 by controlling the substrate temperatures. 相似文献
142.
Seong Shan Yap Wee Ong SiewChen Hon Nee Turid Worren ReenaasTeck Yong Tou 《Thin solid films》2012,520(8):3266-3270
In this work, we investigated the laser ablation and deposition of Si and Ge at room temperature in vacuum by employing nanosecond lasers of 248 nm, 355 nm, 532 nm and 1064 nm. Time-integrated optical emission spectra were obtained for neutrals and ionized Ge and Si species in the plasma at laser fluences from 0.5 to 11 J/cm2. The deposited films were characterized by using Raman spectroscopy, scanning electron microscopy and atomic force microscopy. Amorphous Si and Ge films, micron-sized crystalline droplets and nano-sized particles were deposited. The results suggested that ionized species in the plasma promote the process of subsurface implantation for both Si and Ge films while large droplets were produced from the superheated and melted layer of the target. The dependence of the properties of the materials on laser wavelength and fluence were discussed. 相似文献
143.
利用X射线衍射技术和振动样品磁强计(VSM)研究了巨大晶胞三元化合物Ho117Fe52Ge112的结构与磁性能,测定了外加磁场为0.5T时该化合物的磁矩随温度的变化关系。该化合物具有Tb117Fe52Ge112结构类型,空间群为Fm3m(No.225)点阵参数为a=2.80832(8)nm。在90K到室温的范围内,Ho117Fe52Ge112的磁化率与温度关系服从居里——外斯定律,每个化学式有效磁矩的实验值为ueff=111.25us。测定了室温(300K)时磁矩随外加磁场的变化关系。当外加磁场到2.1T时,该化合物的磁矩约为3.61emu/g,还没有达到饱和状态。 相似文献
144.
Bibhu P. Swain Hidetaka TakatoZhengxin Liu Isao Sakata 《Solar Energy Materials & Solar Cells》2011,95(1):84-88
Surface passivation has been recognized as a crucial step in the evaluation of minority carrier lifetime of photovoltaic materials as well as in the fabrication of high efficient solar cells. Dilute acids of HF and HCl are employed for germanium (Ge) surface passivation. An effective lifetime of passivated Ge wafers has been evaluated by a microwave photoconductive decay (μ-PCD) measurement. Surface recombination velocities, S, of H- and Cl-terminated Ge surfaces are 23 and 37 cm/s, respectively. The stability of passivated Ge surfaces against exposure to air has also been examined. The HCl-passivated Ge surfaces are found to be more robust than HF-passivated surfaces. 相似文献
145.
The quest for higher performance of scaled down technologies resulted in the use of high-mobility substrates and strain engineering approaches. The development of advanced processing modules, based on low temperature processing and deposited (MBE, ALD, epitaxially grown, etc.) gate stacks, has triggered the interest of exploring Ge for sub 32 nm technology nodes. A comparison between Si and Ge for future microelectronics has to take into account a variety of materials, processing and performance aspects. Here special attention will be given to passivation and gate stack formation in relation to device performance, including leakage current and reliability aspects. The potential of Ge-based device structures and the monolithic integration of Ge and III-V devices on silicon are highlighted. 相似文献
146.
利用非平衡态分子动力学模拟方法研究了应变对Ge薄膜热导率的影响。结果表明系统应变对单晶Ge薄膜热导率产生明显影响,热导率随着拉伸应变的增大而减小,随着压缩应变的增大而增大,得出声子速率降低以及薄膜表面重构是产生该模拟结果的内在原因。同时,采用修正的Callaway模型对NEMD结果进行理论验证,两种方法得到的结果吻合得较好。理论结果表明应变弛豫时间对Ge单晶薄膜的热导率产生了重要影响。 相似文献
147.
148.
《Journal of Nuclear Science and Technology》2013,50(5):319-326
Activation cross sections for the (n, 2n) reaction on Nd, Sm, Gd and Yb have been measured at 14.6 MeV by using a Ge(Li) γ-ray detector. The following cross sections (mb) have been obtained: 112Nd 1,675±160, 143Nd 1,789±147, 150Nd 1,720±128, 154Sm 2,010±137, 160Gd 2,173±152, 160Yb 2,226 ±152. These (n,2n) cross sections are compared with the theoretical calculations performed by a new model including pre-equilibrium and statistical models. A good agreement between the experimental and calculated cross sections is obtained. 相似文献
149.
《Journal of Nuclear Science and Technology》2013,50(3):111-116
Uranium in uranyl nitrate-TBP solution was converted into dioxide by vacuum distillation and ignition. In vacuum distillation, TBP and its diluent were recovered at 40°–150°C in nitrogen stream under 1–5mmHg. The residue of distillation was incinerated in nitrogen stream with 0.1~1.OmmHg by raising the temperature from 400° to 1,300°C. The final product is a black powder of UO2, identified by X-ray diffraction, by density measurement and by chemical analyses. Uranyl nitrate TBP solution is evolved during fuel reprocessing, and thus the vacuum distillation reported here could be applied to the solution in order to simplify the process. 相似文献
150.
Alireza Samavati Zulkafli Othaman Sib Krishna Ghoshal Mohammad Reza Dousti Mohammed Rafiq Abdul Kadir 《International journal of molecular sciences》2012,13(10):12880-12889
The visible luminescence from Ge nanoparticles and nanocrystallites has generated interest due to the feasibility of tuning band gap by controlling the sizes. Germanium (Ge) quantum dots (QDs) with average diameter ~16 to 8 nm are synthesized by radio frequency magnetron sputtering under different growth conditions. These QDs with narrow size distribution and high density, characterized using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) are obtained under the optimal growth conditions of 400 °C substrate temperature, 100 W radio frequency powers and 10 Sccm Argon flow. The possibility of surface passivation and configuration of these dots are confirmed by elemental energy dispersive X-ray (EDX) analysis. The room temperature strong visible photoluminescence (PL) from such QDs suggests their potential application in optoelectronics. The sample grown at 400 °C in particular, shows three PL peaks at around ~2.95 eV, 3.34 eV and 4.36 eV attributed to the interaction between Ge, GeOx manifesting the possibility of the formation of core-shell structures. A red shift of ~0.11 eV in the PL peak is observed with decreasing substrate temperature. We assert that our easy and economic method is suitable for the large-scale production of Ge QDs useful in optoelectronic devices. 相似文献