Visible photoluminescence from Ge nanoclusters implanted in nanoporous aluminum oxide films

Nanoporous aluminum oxide (Al₂O₃) films with uniform porous size of 45 nm prepared by the electrochemical process in inorganic acid medium were implanted at room temperature (RT) with 120 keV Ge⁺ ions with a fluence of 1.2×10¹⁶ cm⁻². The nucleation and growths of Ge nanoparticles, were obtained by thermal annealing of the implanted samples at the temperature range of 200-600 °C. The size and distribution of the nanoparticles were characterized by photoluminescence (PL) measurements. The photoluminescence measurements as a function of the annealing temperature shows that at low annealing temperature (200 °C), the sample presents a low intensity and broad emission band centered at 5456 Å consistent with emission band characteristics of nanocluster of Ge with diameter in the range of 4-8 nm, as the annealing temperature increases to 400 °C the PL intensity increases by a factor of almost 20 and the emission band suffers a small red shift. The intensity increases can be related to the increase of the number of Ge nanocluster. At the annealing temperature of 600 °C, the emission band is considerably red shifted by almost 172 Å and the emission intensity decreases significantly, strongly suggesting that nanocrystalline Ge having a character of direct optical transitions exhibits the visible photoluminescence.     

二辛基硫醚在贵金属元素分析上的应用 Ⅰ.地质样品中痕量银的中子活化分析

本文研究了二辛基硫醚的萃取性能并将其用于地质样品中痕量银的中子活化分析(NAA)。将地质样品于反应堆(中子通量为(4-7)×10~(13)n/cm~2·s)中照射200h,冷却一个月以上,用HF-HNO_3-HClO_4分解样品,于1N HNO_3介质中用0.2M二辛基硫醚-氯仿溶液萃取,有机相作Ge(Li)γ谱分析,用相对比较法求出样品中银含量。化学产额为92％。分析了水系沉积物、岩石和土壤标样,测得银的含量范围为0.023-4.35ppm,实际样品的测定精密度在±15％以内。     

122—1400keV能区同轴Ge(Li)和HpGe探测器效率曲线的函数拟合

在能量为122—1400keV范围内最优化方法用于四参数表达式ε=(a_1/E)~(a_2)+a_3Exp(-a_4E)和实验测定的同轴Ge(Li)和HpGe探测器效率的拟合。给出了初值计算方法。拟合结果是好的,实验和拟合值之间平均偏离小于2.0％。     

高剂量离子注入直接形成Ge纳米晶的物理机理

研究了单束双能高剂量Ge离子注入、不经过退火在非晶态SiO2薄膜中直接形成镶嵌结构Ge纳米晶的物理机制．实验中利用不加磁分析器的离子注入机，采用Ge弧光放电离化自动形成的Ge+和Ge2+双电荷离子并存的单束双能离子注入方法，制备了1e16～1e18cm－2多种剂量Ge离子注入的Si基SiO2薄膜样品．用GIXRD表征了Ge纳米晶的存在，并仔细分析得到了纳米晶形成的阈值剂量．通过TEM分析了Ge纳米晶的深度分布和晶粒尺寸．用SRIM程序分别计算了双能离子在SiO2非晶层的射程和深度分布，与实验结合，得到纳米晶形成的物理机制，即纳米晶的形成与单束双能离子注入时Ge＋和Ge2＋相互碰撞产生的能量沉积在SiO2中形成的局域高温有关．     

Si(001)斜切衬底上Ge量子点的固相外延生长

研究了Si(001)面偏[110]方向6°斜切衬底上Ge量子点的固相外延生长.实验结果表明,在Si(001)6°斜切衬底上固相外延生长Ge量子点的最佳退火温度为640℃,在斜切衬底上成岛生长的临界厚度低于在Si(001)衬底成岛生长的临界厚度,6°斜切衬底上淀积0.7nm Ge即可成岛,少于Si(001)衬底片上Ge成岛所需的淀积量.从Ge量子点的密度随固相外延温度的变化曲线,得到Ge量子点的激活能为1.9eV,远高于Si(111)面上固相外延Ge量子点的激活能0.3eV.实验亦发现,在Si(001)斜切衬底上固相外延生长的Ge量子点较Si(001)衬底上形成的量子点的热稳定性要好.     

使用低温电荷灵敏前置放大器的新型Ge（Li）探测器

本文介绍了使用低温电荷灵敏放大器的Ge(Li)探测器的设计、调整及性能,它能方便地配用反符合环探测器。     

Surface Event Rejection of the EDELWEISS Cryogenic Germanium Detectors Based on NbSi Thin Film Sensors

Near-surface-events are a major limitation to the performance of cryogenic massive germanium heat and ionisation detectors for dark matter search, due to their incomplete charge collection. We present here a powerful method of surface event identification based on the transient heat signal of a Ge bolometer, equipped with two NbSi high impedance thin film sensors. Calibration runs using electrons and low energy gamma particles from a ¹⁰⁹Cd source show highly effective surface event rejection down to the heat threshold energy. Neutron and gamma source calibrations were realised to get information on the fiducial volume of the Ge absorber. First results from low background data taking are discussed.     

Self-organization of a 2D lattice on a surface of Ge single crystal after irradiation with Nd:YAG laser

Experimentally observed self-organization of a 2D lattice on the surface of Ge single crystal after irradiation by pulsed Nd:YAG laser is reported. The 2D lattice consists of nano-size hills arranged in a pattern of C_6i point group symmetry and is characterized by translational symmetry with the period of 1 μm. Calculations of time-dependent distribution of temperature in the bulk of the Ge sample are presented to explain the phenomenon. The calculations show that overheating of the crystal lattice occurs at laser radiation intensities exceeding 30 MW/cm². According to synergetic ideas, the presence of the non-equilibrium liquid phase of Ge and a huge gradient of temperature (∼3×10⁸ K/m) can lead to self-organization of the 2D lattice similar to Benard cells.     

改进的“三图法”在煤矿顶板水害评价中的应用——以东胜煤田台格庙勘查区为例

通过建立台格庙勘查区首采煤层冒裂安全性分区图和煤层顶板含水层富水性分区图,来对煤层顶板的含水层涌(突)水条件进行评价。针对勘查区煤层厚度变化大、顶板无稳定隔水层,顶板含水层富水性较弱的特点,在传统的“三图法”基础上,充分考虑了含水层的富水性和导水裂缝带发育高度这两个因素,选用导水裂缝带高度与含水层厚度的百分比来表示导水裂缝带发育高度对含水层涌(突)水的影响,在此基础上对首采煤层顶板含水层涌(突)水条件进行综合分区评价。四井田中部及二井田北部地区涌(突)水危险性为较危险区,三井田北部、五井田南部及勘查区南部局部地区涌(突)水危险性为过渡区,其他地段为安全区、较安全区。针对顶板充水含水层涌(突)水条件综合分区,提出了疏放水、注浆、监测等防治水措施建议。