4He+辐照非晶态合金引起的表面形貌变化

室温~4He~+辐照Fet_(11)B_(?)Si_3,Cr_2和Ni_(?)B_(?)Si_5非晶态合金,利用扫描电子显微镜(SEM)观测表面形貌随辐照参数的变化,同时给出表面形变,即发泡或层离的临界剂量范围,以及发泡直径分布算实验结果.关键词：     

Ar+8轰击石墨表面损伤的扫描隧道显微镜观测研究

报道了用10—112MeV能量的Ar+8离子轰击高定向石墨造成损伤的原子水平观测结果,给出了损伤形貌、损伤大小和损伤数密度.讨论了损伤与表面核能损的关系及损伤过程的可能机制.     

Angular dependence of multiple-bit upset response in static random access memories under heavy ion irradiation

Experimental evidence is presented relevant to the angular dependences of multiple-bit upset (MBU) rates and patterns in static random access memories (SRAMs) under heavy ion irradiation. The single event upset (SEU) cross sections under tilted ion strikes are overestimated by 23.9% 84.6%, compared with under normally incident ion with the equivalent linear energy transfer (LET) value of ～ 41 MeV/(mg/cm 2 ), which can be partially explained by the fact that the MBU rate for tilted ions of 30 is 8.5%-9.8% higher than for normally incident ions. While at a lower LET of ～ 9.5 MeV/(mg/cm 2 ), no clear discrepancy is observed. Moreover, since the ion trajectories at normal and tilted incidences are different, the predominant double-bit upset (DBU) patterns measured are different in both conditions. Those differences depend on the LET values of heavy ions and devices under test. Thus, effective LET method should be used carefully in ground-based testing of single event effects (SEE) sensitivity, especially in MBU-sensitive devices.     

Fluorinated <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">n</Emphasis> type copolyfluorene as polymer electret for stable nonvolatile organic transistor memory device

In this study, a kind of fluorinated copolyfluorene, named poly[(4-(octyloxy)-9,9-diphenylfluorene-2,7-diyl)-alt-(2,3,5,6-tetrafluoro-1,4-phenylene)] (PODPF-TFP), is synthesized by facile palladium-based direct aromatization. Compared to the non-fluorinated counterpart, poly[(4-(octyloxy)-9,9-diphenylfluorene-2,7-diyl)-alt-(p-phenylene)] (PODPF-P), deeper HOMO/LUMO energy level combined with steric hindrance effect endow PODPF-TFP with excellent spectra and morphology stability. Finally, organic field-effect transistor (OFET) memory devices are fabricated with PODPF-P/PODPFTFP as the dielectric layers, and they both exhibit flash type storage characteristic. Owing to the electronegativity of fluorine atom, the device based on PODPF-TFP exhibits larger memory window and more stable I _on/I _off ratio during a retention time of 10⁴ s as well as a better aging stability. The present study suggests that fluorinated p-n copolyfluorene electrets could enhance the capabilities of charge trapping and storage, which are promising for OFET memory devices.     

调焦方式对测绘相机主点位置的影响

考虑测绘相机调焦会影响相机的主点位置,从而改变相机的内方位元素,降低立体测绘精度,故本文分析了空间相机常用的3种调焦方式（镜组调焦、平面反射镜调焦、焦面调焦）对测绘相机主点位置的影响。简要介绍3种调焦方式的工作原理,研究了理想情况下3种调焦方式对主点位置的影响。在考虑系统装凋误差的情况下,建立了主点位置变化量与调焦量之间的数学模型,通过实例计算得出焦面调焦易满足测绘相机主点定位精度〈0．2pixel,是最适合的调焦方式。最后,以某一型号相机调焦机构为实验对象,对平面反射镜方式对主点的位置变化进行了实验量测,结果证明了提出的主点位置变化量理论计算公式的准确性和分析得到的不同调焦方式对主点位置影响的正确性,该公式可以用于指导测绘相机调焦方式的选择,以满足高精度测绘的需要。     

Influences of total ionizing dose on single event effect sensitivity in floating gate cells

The influences of total ionizing dose(TID) on the single event effect(SEE) sensitivity of 34-nm and 25-nm NAND flash memories are investigated in this paper. The increase in the cross section of heavy-ion single event upset(SEU) in memories that have ever been exposed to TID is observed, which is attributed to the combination of the threshold voltage shifts induced by γ-rays and heavy ions. Retention errors in floating gate(FG) cells after heavy ion irradiation are observed.Moreover, the cross section of retention error increases if the memory has ever been exposed to TID. This effect is more evident at a low linear energy transfer(LET) value. The underlying mechanism is identified as the combination of the defects induced by γ-rays and heavy ions, which increases the possibility to constitute a multi-trap assisted tunneling(mTAT) path across the tunnel oxide.     

重离子辐照SiO2的光致发光

基于荷能离子与固体相互作用特点,提出了一种新的制备光致发光材料的方法-- 高能重离子辐照. 用这种方法研究了SiO2薄膜的光致发光特性,发现高能84K r和40Ar离子辐照可在注碳SiO2薄膜样品中产生强的蓝-紫光发射带,掺杂碳增强了辐照样品的发光特性.