Synergistic effect of total ionizing dose on single event effect induced by pulsed laser microbeam on SiGe heterojunction bipolar transistor

The synergistic effect of total ionizing dose(TID) on single event effect(SEE) in SiGe heterojunction bipolar transistor(HBT) is investigated in a series of experiments. The SiGe HBTs after being exposed to 60 Co g irradiation are struck by pulsed laser to simulate SEE. The SEE transient currents and collected charges of the un-irradiated device are compared with those of the devices which are irradiated at high and low dose rate with various biases. The results show that the SEE damage to un-irradiated device is more serious than that to irradiated SiGe HBT at a low applied voltage of laser test. In addition, the g irradiations at forward and all-grounded bias have an obvious influence on SEE in the SiGe HBT, but the synergistic effect after cutting off the g irradiation is not significant. The influence of positive oxide-trap charges induced by TID on the distortion of electric field in SEE is the major factor of the synergistic effect. Moreover, the recombination of interface traps also plays a role in charge collection.     

石墨烯场效应晶体管的X射线总剂量效应

本文针对不同结构、尺寸的石墨烯场效应晶体管(graphene field effect transistors, GFET)开展了基于10 keVX射线的总剂量效应研究.结果表明,随累积剂量的增大,不同结构GFET的狄拉克电压V_Dirac和载流子迁移率μ不断退化;相比于背栅型GFET,顶栅型GFET的辐射损伤更加严重;尺寸对GFET器件的总剂量效应决定于器件结构; 200μm×200μm尺寸的顶栅型GFET损伤最严重,而背栅型GFET是50μm×50μm尺寸的器件损伤最严重.研究表明:对于顶栅型GFET,辐照过程中在栅氧层中形成的氧化物陷阱电荷的积累是V_Dirac和μ降低的主要原因.背栅型GFET不仅受到辐射在栅氧化层中产生的陷阱电荷的影响,还受到石墨烯表面的氧吸附的影响.在此基础上,结合TCAD仿真工具实现了顶栅器件氧化层中辐射产生的氧化物陷阱电荷对器件辐射响应规律的仿真.相关研究结果对于石墨烯器件的抗辐照加固研究具有重大意义.