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.     

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.     

不同粒子辐射条件下CC4013器件辐射损伤研究

本文采用60 MeV Br离子、5 MeV质子和1 MeV电子等三种辐射源, 针对CC4013型互补金属氧化物半导体器件(complementary metal oxide semiconductor, CMOS)进行辐射损伤研究. 通过Geant4程序计算了该器件电离辐射吸收剂量与芯片厚度的关系, 经过计算, 在相同注量下, 60 MeV Br离子的电离吸收剂量最大, 1 MeV电子产生的电离吸收剂量最小. 应用Keithley4200-SCS半导体特性分析仪在原位条件下研究了CC4013器件电性能参数随辐射吸收剂量的变化关系. 测试结果表明, 相同电离辐射吸收剂量下, 1 MeV电子对CC4013器件的阈值电压参数影响最大, 5 MeV质子其次, 60 MeV Br离子的影响最弱. 关键词： CMOS器件 高能带电粒子 电离辐射 辐射损伤     

质子辐射损伤对单结GaAs/Ge太阳电池暗特性参数的影响

基于p-n结暗特性双指数模型,对经质子辐射后的单结GaAs/Ge太阳电池的暗特性I-V曲线进行数值拟合,确定了单结GaAs/Ge太阳电池在辐射前后的四个暗特性特征参数,即串联电阻R_s、并联电阻R_(sh)、扩散电流I_(s1)和复合电流I_(s2).研究结果表明,质子辐射后单结GaAs/Ge太阳电池的R_s,R_(sh),I_(s1)和I_(s2)四个暗特性参数均发生显著变化.经低能质子辐射后,单结GaAs/Ge太阳电池的R_(sh)随位移损伤剂量的增加而减小,而R_s,I_(s1)和I_(s2)三个参数随位移损伤剂量的增加而增大,其中串联电阻随位移损伤剂量线性增加而与辐射质子能量无关.理论分析表明,上述参数的变化与质子辐射损伤区域分布有关.基区和发射区的损伤主要引起单结电池串联电阻和扩散电流的增加;结区的损伤导致并联电阻减小,复合电流增大.