Effect of bias condition on heavy ion radiation in bipolar junction transistor

The characteristic degradations in silicon NPN bipolar junction transistor (BJT) of 3DG142 type are examined under the irradiation with 40-MeV chlorine (Cl) ions under forward, grounded, and reverse bias conditions, respectively. Different electrical parameters are in-situ measured during the exposure under each bias condition. From the experimental data, larger variation of base current (I_B) is observed after irradiation at a given value of base-emitter voltage (V_BE), while the collector current is slightly affected by irradiation at a given V_BE. The gain degradation is affected mostly by the behaviour of the base current. From the experimental data, the variation of current gain in the case of forward bias is much smaller than that in the other conditions. Moreover, for 3DG142 BJT, the current gain degradation in the case of reverse bias is more severe than that in the grounded case at low fluence, while at high fluence, the gain degradation in the reverse bias case becomes smaller than that in the grounded case.     

Effect of bias condition on heavy ion radiation in bipolar junction transistors

The characteristic degradations in a silicon NPN bipolar junction transistor(BJT) of 3DG142 type are examined under irradiation with 40-MeV chlorine(Cl) ions under forward,grounded,and reverse bias conditions,respectively.Different electrical parameters are in-situ measured during the exposure under each bias condition.From the experimental data,a larger variation of base current(I B) is observed after irradiation at a given value of base-emitter voltage(V BE),while the collector current is slightly affected by irradiation at a given V BE.The gain degradation is affected mostly by the behaviour of the base current.From the experimental data,the variation of current gain in the case of forward bias is much smaller than that in the other conditions.Moreover,for 3DG142 BJT,the current gain degradation in the case of reverse bias is more severe than that in the grounded case at low fluence,while at high fluence,the gain degradation in the reverse bias case becomes smaller than that in the grounded case.     

温度和应变速率耦合作用下纳米晶Ni压缩行为研究

本文利用低温力学测试系统研究了电化学沉积纳米晶Ni在不同温度和宽应变速率条件下的压缩行为. 借助应变速率敏感指数、激活体积、扫描电子显微镜及高分辨透射电子显微镜方法, 对纳米晶Ni的压缩塑性变形机理进行了表征. 研究表明, 在较低温度条件下, 纳米晶Ni的塑性变形主要是由晶界位错协调变形主导, 晶界本征位错引出后无阻碍的在晶粒内无位错区运动, 直至在相对晶界发生类似切割林位错行为. 并且, 在协调塑性变形时引出位错的残留位错能够增加应变相容性和减小应力集中; 在室温条件下, 纳米晶Ni的塑性变形机理主要是晶界-位错协调变形与晶粒滑移/旋转共同主导. 利用晶界位错协调变形机理和残留位错运动与温度及缺陷的相关性揭示了纳米晶Ni在不同温度、不同应变速率条件下力学压缩性能差异的内在原因.     

Incident particle range dependence of radiation damage in a power bipolar junction transistor

The characteristic degradations in silicon NPN bipolar junction transistors(BJTs) of type 3DD155 are examined under the irradiations of 25-MeV carbon(C),40-MeV silicon(Si),and 40-MeV chlorine(Cl) ions respectively.Different electrical parameters are measured in-situ during the exposure of heavy ions.The experimental data shows that the changes in the reciprocal of the gain variation((1/β)) of 3DD155 transistors irradiated respectively by 25-MeV C,40-MeV Si,and 40-MeV Cl ions each present a nonlinear behaviour at a low fluence and a linear response at a high fluence.The(1/β) of 3DD155 BJT irradiated by 25-MeV C ions is greatest at a given fluence,a little smaller when the device is irradiated by 40-MeV Si ions,and smallest in the case of the 40-MeV Cl ions irradiation.The measured and calculated results clearly show that the range of heavy ions in the base region of BJT affects the level of radiation damage.     

Radiation effects on MOS and bipolar devices by 8 MeV protons, 60 MeV Br ions and 1 MeV electrons

The radiation effects of the metal-oxide-semiconductor (MOS) and the bipolar devices are characterised using 8~MeV protons, 60~MeV Br ions and 1~MeV electrons. Key parameters are measured {\it in-situ} and compared for the devices. The ionising and nonionising energy losses of incident particles are calculated using the Geant4 and the stopping and range of ions in matter code. The results of the experiment and energy loss calculation for different particles show that different incident particles may give different contribution to MOS and bipolar devices. The irradiation particles, which cause larger displacement dose within the same chip depth of bipolar devices at a given total dose, would generate more severe damage to the voltage parameters of the bipolar devices. On the contrary, the irradiation particles, which cause larger ionising damage in the gate oxide, would generate more severe damage to MOS devices. In this investigation, we attempt to analyse the sensitivity to radiation damage of the different parameter of the MOS and bipolar devices by comparing the irradiation experimental data and the calculated results using Geant4 and SRIM code.     

晶粒尺寸对1 MeV电子在金属Ni中能量沉积的影响

采用脉冲电沉积方法制备出高致密、高质量的纳米晶Ni, 并对其密度、组织成分和微观结构进行了表征. 利用高能粒子加速器产生的1 MeV高能电子为辐照源, 研究高能电子在纳米晶Ni和常规粗晶Ni中的能量损失. 通过辐照过程中放置的吸收剂量片来准确表征其电子的能量沉积. 结果表明, 晶粒尺寸对高能电子在材料中的能量沉积有明显的影响, 1 MeV电子在穿过一定厚度的金属Ni后, 在晶粒尺寸细小的纳米晶Ni中测得总的吸收剂量较大, 证明了高能电子在纳米材料中的总能量沉积较小, 从而表现出纳米材料抗辐照的优异性能. 关键词： 高能电子 纳米金属 辐射损伤     

偏置条件对NPN及PNP双极晶体管电离辐射损伤的影响研究

本文采用低能电子辐照源对NPN及PNP晶体管进行辐照试验. 在辐照试验过程中, 针对NPN及PNP晶体管发射结施加不同的偏置条件, 研究偏置条件对NPN及PNP晶体管辐射损伤的影响. 使用Keithley 4200-SCS半导体特性测试仪在原位条件下测试了双极晶体管电性能参数随低能电子辐照注量的变化关系. 测试结果表明, 在相同的辐照注量条件下, 发射结反向偏置时双极晶体管的辐照损伤程度最大; 发射结正向偏置时双极晶体管的辐照损伤程度最小; 发射结零偏时双极晶体管的辐照损伤程度居于上述情况之间. 关键词： 双极晶体管 低能电子 电离辐射     

Degradation mechanisms of current gain in NPN transistors

An investigation of ionization and displacement damage in silicon NPN bipolar junction transistors (BJTs) is presented. The transistors were irradiated separately with 90-keV electrons, 3-MeV protons and 40-MeV Br ions. Key parameters were measured {\em in-situ} and the change in current gain of the NPN BJTS was obtained at a fixed collector current (I_{\rm c}=1~mA). To characterise the radiation damage of NPN BJTs, the ionizing dose D_{\i} and displacement dose D_{\d} as functions of chip depth in the NPN BJTs were calculated using the SRIM and Geant4 code for protons, electrons and Br ions, respectively. Based on the discussion of the radiation damage equation for current gain, it is clear that the current gain degradation of the NPN BJTs is sensitive to both ionization and displacement damage. The degradation mechanism of the current gain is related to the ratio of D_{\rm d}/(D_{\rm d}+D_{\rm i}) in the sensitive region given by charged particles. The irradiation particles leading to lower D_{\rm d}/(D_{\rm d}+D_{\rm i}) within the same chip depth at a given total dose would mainly produce ionization damage to the NPN BJTs. On the other hand, the charged particles causing larger D_{\rm d}/(D_{\rm d}+D_{\rm i}) at a given total dose would tend to generate displacement damage to the NPN BJTs. The Messenger--Spratt equation could be used to describe the experimental data for the latter case.     

Si_3N_4钝化层对横向PNP双极晶体管电离辐射损伤的影响机理

航天器中电子器件在轨服役期间,会遭受到空间带电粒子及各种射线的辐射环境的显著影响,易于造成电离辐射损伤.本文采用60Coγ射线辐照源,针对有/无Si_3N_4钝化层结构的横向PNP型(LPNP)双极晶体管,开展了电离辐射损伤效应及机理研究.利用KEITHLEY 4200-SCS半导体参数测试仪测试了LPNP晶体管电性能参数(包括Gummel特性曲线和电流增益等).采用深能级瞬态谱分析仪(DLTS),对辐照前后有/无Si_3N_4钝化层结构的LPNP晶体管的电离缺陷进行测试.研究结果表明,在相同吸收剂量条件下,与无Si_3N_4钝化层的晶体管相比,具有Si_3N_4钝化层的LPNP晶体管基极电流退化程度大,并且随吸收剂量的增加,电流增益退化更为显著.通过DLTS分析表明,与无Si_3N_4钝化层的晶体管相比,有Si_3N_4钝化层的晶体管辐射诱导的界面态能级位置更接近于禁带中心.这是由于制备Si_3N_4钝化层时引入了大量的氢所导致,而氢的存在会促使辐射诱导的界面态能级位置更接近于禁带中心,复合率增大,从而加剧了晶体管性能的退化.     

170keV质子辐照对多壁碳纳米管薄膜微观结构与导电性能的影响

碳纳米管具有优异的导电性, 是未来电子元器件的理想候选材料, 应用前景广阔. 针对碳纳米管在空间电子元器件的应用需求, 本文研究了170 keV质子辐照对多壁碳纳米管薄膜微观结构与导电性能的影响. 采用扫描电子显微镜(SEM)、拉曼光谱仪(Raman)、X射线光电子能谱仪(XPS)及电子顺磁共振谱仪(EPR)对辐照前后碳纳米管试样的表面形貌和微观结构进行分析; 利用四探针测试仪对碳纳米管薄膜进行导电性能分析. SEM分析表明, 170 keV质子辐照条件下, 当辐照注量高于5×10¹⁵ p/cm² (protons/cm²)时, 碳纳米管薄膜表面变得粗糙疏松, 纳米管发生明显弯曲、收缩及相互缠结现象. 目前, 质子辐照纳米管发生的收缩现象被首次发现. 基于Raman和XPS分析表明, 170 keV质子辐照后碳纳米管的有序结构得到改善, 且随辐照注量增加, 碳纳米管的有序结构改善明显. 结构的改善主要是由于170 keV质子辐照碳纳米管所产生的位移效应导致缺陷重组. EPR分析表明, 随着辐照注量的增加, 碳纳米管薄膜内的非局域化电子减少. 利用四探针测试分析表明, 碳纳米管薄膜的导电性能变差, 这是由于170 keV质子辐照导致碳纳米管薄膜中的电子特性及形态发生改变. 本文研究结果有助于利用质子辐照对碳纳米管膜结构和性能进行调整, 从而制备出抗辐射的纳米电子器件.