部分耗尽SOI MOSFET总剂量效应与偏置状态的关系

实验表明SOI MOSFET掩埋氧化层中的总剂量辐射效应与辐射过程中的偏置状态有关. 对诱发背沟道泄漏电流的陷阱电荷进行了研究. 建立一个数值模型来模拟不同偏置下陷进电荷的建立, 它包括辐射产生的载流子复合和俘获的过程. 模拟结果与实验结果相符, 解释了总剂量辐射效应受偏置状态影响的机理.     

Improvement of total-dose irradiation hardness of silicon-on-insulator materials by modifying the buried oxide layer with ion implantation

The hardening of the buried oxide (BOX) layer of separation by implanted oxygen (SIMOX) silicon-on-insulator (SOI) wafers against total-dose irradiation was investigated by implanting ions into the BOX layers. The tolerance to total-dose irradiation of the BOX layers was characterized by the comparison of the transfer characteristics of SOI NMOS transistors before and after irradiation to a total dose of 2.7 Mrad(SiO₂. The experimental results show that the implantation of silicon ions into the BOX layer can improve the tolerance of the BOX layers to total-dose irradiation. The investigation of the mechanism of the improvement suggests that the deep electron traps introduced by silicon implantation play an important role in the remarkable improvement in radiation hardness of SIMOX SOI wafers.     

Research on total-dose hardening for H-gate PD NMOSFET/SIMOX by ion implanting into buried oxide

In this work, we investigate the back-gate I-V characteristics for two kinds of NMOSFET/ SIMOX transistors with H gate structure fabricated on two different SOI wafers. A transistors are made on the wafer implanted with Si⁺ and then annealed in N₂,and B transistors are made on the wafer without implantation and annealing. It is demonstrated experimentally that A transistors have much less back-gate threshold voltage shift ΔV_th than B transistors under X-ray total dose irradiation. Subthreshold charge separation technique is employed to estimate the build-up of oxide charge and interface traps during irradiation, showing that the reduced ΔV_th for A transistors is mainly due to its less build-up of oxide charge than B transistors. Photoluminescence (PL) research indicates that Si implantation results in the formation of silicon nanocrystalline (nanocluster) whose size increases with the implant dose. This structure can trap electrons to compensate the positive charge build-up in the buried oxide during irradiation, and thus reduce the threshold voltage negative shift.     

应用数量分析法综合评价医院各年度工作质量

科学评价医院各年度工作质量.用主成分分析和因子分析法对医院九年工作质量进行综合评价.我校附属口腔医院在1997至2006九年中工作质量综合评价排序结果为9、7、6、5、8、4、2、3、1.该方法可消除人为因素干扰,对综合评价医院各年度工作质量效果有应用价值,简单易行.     

解函数图像题的技巧

中考有关函数图像题分为三种:(1)联系生活结合实际的;(2)用解析式判别图像;(3)根据图像和解析式判别不等式.一、联系生活实际的例1一慢车和一快车沿相同的路线从A到B地,所行的路程与时间的函数图像如图所示,试根据图像,回答下列问题:     

液相色谱-串联质谱法测定牛奶中35种四环素类、磺胺类、青霉素类、大环内酯类、氯霉素类抗生素残留

建立了液相色谱-质谱测定牛奶中35种四环素类、磺胺类、青霉素类、大环内酯类、氯霉素类等5类抗生素残留的检测方法。样品经碱性乙腈-Mcllvaine缓冲液超声提取,用Eclipse XDB-C₈色谱柱(150 mm×2.1 mm, 3.5 μm)分离,梯度洗脱,流速0.25 mL/min,进样量10 μL,采用多反应监测正离子或负离子模式,可以一次性对牛奶中的目标化合物进行定性和定量测定。在优化条件下,35种化合物的检出限均低于10.0 μg/kg,方法回收率为70.1%~109.9%,相对标准偏差(RSD)为2.89%~9.99%。结果表明该方法适用于牛奶中抗生素残留的检测。采用所建立的检测方法对市售的50种不同乳品进行了检测,其中一个样品检出氯霉素含量为0.48 μg/kg。检测结果表明,中国市场上销售的乳品氯霉素污染的风险仍然存在。本研究建立的液相色谱-质谱联用方法实现了牛奶中35种四环素类、磺胺类、青霉素类、大环内酯类、氯霉素类等5类抗生素残留的测定。该方法简单、快捷、经济,可实现多种抗生素残留的快速测定。     

采用硅离子注入改进SIMOX埋氧的抗总剂量辐射性能研究

采用硅离子注入工艺对注氧隔离(SIMOX)的绝缘体上硅(SOI)材料进行改性, 在改性材料和标准SIMOX材料上制作了部分耗尽环型栅NMOS/SOI晶体管, 并对其进行⁶⁰Co γ射线总剂量辐照试验. 通过背栅的I-V特性表征晶体管的总剂量辐照特性. 结果表明, 在埋氧层注硅可以降低NMOS/SOI受辐照引起的背栅阈值电压漂移, 提高埋氧层的抗总剂量能力.