Microstructural Effects of Ion Implantation on Molybdenum

The effects of ion implantation and subsequent annealing on the microstructure of molybdenum have been investigated by transmission electron microscopy. The ions investigated were carbon, nitrogen, and tellurium. The ion-induced damage was found to give rise to grain boundary migration phenomena both during implantation and during subsequent annealing. Precipitation or ordering was found to occur for each ion on annealing.     

特征X射线能谱法测定Fe^＋注入小麦种子的深度

用１１０ｋｅＶ Ｆｅ＾＋离子束垂直注入小麦种胚后，在扫描电子显微镜上沿种子纵沟剖面，在不同深度上测量Ｆｅ元素被激发出的特征Ｘ射线强度分布，结果表明分布呈指数衰减，与晶体中的热扩散分布相类似，并对此进行了讨论。     

硅中硼离子注入校准样品的研制

本文主要介绍了硅中硼离子注入校准样品的制备与研究。分别用三台SIMS仪器对样品进行了深度剖析与比对,并对用作校准目的的样品主要参数进行了定值。     

Ionoluminescence decay measured with single ions

A new ion beam analysis-based, single ion technique called the time to first photon has been developed to measure the decay of the luminescence signal of phosphors. Such measurements are currently needed to study luminescence decay mechanisms following high-density excitations and to identify strongly luminescent phosphor coatings with short lifetimes for ion photon emission microscopy (IPEM). The samples for this technique consist of thin phosphor layers placed or coated on the surface of PIN diodes. Single ions from an accelerator strike this sample and simultaneously create ion beam induced luminescence (IBIL) from the phosphor that is measured by a single-photon-detector, and an ion beam induced charge collection (IBICC) signal in the PIN diode. In this case, the IBICC signal provides the start pulse and the IBIL signal the stop pulse to a time to amplitude converter. It is straightforward to show that this approach also measures a signal proportional to activity versus time with an accuracy of 5% as long as the number of detected photons per ion is less than 0.1, which usually requires the use of absorbers for the IBIL detector or electronic discrimination for the IBIL signals. Details of the new analysis are given together with examples of luminescence decay measurements of several ceramic phosphors being considered to coat IPEM samples. IPEM is currently being developed at Sandia National Laboratory (SNL), the University of North Texas in Denton, and the Universities and INFN of Padova and Torino.     

Accurate depth profiling through energy-dependent pulse height deficit compensation in gas ionization detectors

The impact of the pulse height deficit effect in gas ionization detectors on the accurate extraction of depth information from heavy ion elastic recoil detection spectra has been investigated. Thin GaN films and Ge_xSi_1−x/Si heterostructures have been analyzed with a 200 MeV ¹⁹⁷Au beam. Employing an empirical parameterisation of the pulse height deficit, a global energy calibration of the detector can be achieved. Energy spectra have been compared, calibrated with either a constant or a full energy-dependent compensation for the deficit. A constant compensation results in significant distortion of the extracted depth profile for heavier ions, whereas an energy-dependent compensation yields true concentration–depth profiles.     

Ion implantation doping of OMCVD grown GaN

Doping by ion implantation using Si, O, Mg, and Ca has been studied in single crystal semi-insulating and n-type GaN grown on a-sapphire substrates. The n-and p-type dopants used in this study are Si and O; Mg and Ca, respectively. Room temperature activation of Si and O donors has been achieved after 1150°C annealing for 120 s. The activation of Mg and Ca acceptors is too low to measure at both room temperature and 300°C. Using higher doses to achieve a measurable p-type conduction increases the amount of damage created by the implantation. Rutherford back scattering measurements on this material indicate that the damage is still present even after the maximum possible heat treatment. Secondary ion mass spectrometry measurements have indicated a redistribution in the measured profiles of Mg due to annealing.     

低功率激光对细胞质膜通透性及细胞功能的影响

目的:探索低功率激光对细胞质膜通透性及细胞功能的影响。方法:以波长为632.8nm,功率密度为5.4mW/cm~2的氦氖激光照射人外周血淋巴细胞15、30、60分钟,并采用钙荧光指示剂Fura—2/Am定量测试法检测淋巴细胞内游离钙浓度和质膜Ca~(2+)—Mg~(2+)—ATP酶活性变化。结果:照射后淋巴细胞内游离钙浓度明显低于正常(P<0.05);同时细胞膜Ca~(2+)—Mg~(2+)—ATP酶活性增加(P<0.05);而且照射后细胞内游离钙浓度降低与质膜上Ca~(2+)—Mg~(2+)—ATP酶的激活呈负相关。结论:低功率激光照射激活细胞膜Ca~(2+)—Mg~(2+)—ATP酶活性,使细胞膜对钙通透性发生变化,且影响到细胞内Ca~(2+)贮存,造成细胞膜通透性和细胞功能的改变。     

GaAs亚微米自对准工艺技术研究

总结了在５０ｍｍＧａＡｓ圆片上实现自对准介质膜隔离等平面工艺技术的研究，着重描述了离子注入、自对准亚微米难熔栅制备、钝化介质膜生长、干法刻蚀、电阻和电容制备等关键工艺的研究结果。这套工艺的均匀性、重复性好，在５０ｍｍＧａＡｓ圆片上获得了满意的成品率。采用这套工艺已成功地研制出多种性能良好的ＧａＡｓＩＣ和ＧａＡｓ功率ＭＥＳＦＥＴ，证明国家自然科学基金委员会这一重大课题的选择对发展我国ＧａＡｓＩＣ确实具有重大意义。     

微波辐射电镜生物样品制备方法研究

本文报道一种快速微波辐射电镜样品制备方法──水浴法，以及这个方法在动植物样品超薄切片制备中的应用。实验结果表明，水浴法使得样品可以接受相对较长时间的微波辐射而不致造成任何损伤，浸泡液和样品的温度控制简单而且准确，样品处理的结果内外均匀一致，超微结构保存优秀，完全可与常规制样法和Ｌｏｇｉｎ法的结果相媲美，而且在某些方面水浴法要优于常规法和Ｌｏｇｉｎ法。