Increased Radiation Hardness of Short-Channel Electron-Irradiated Si1-xGex Source/Drain p-Type Metal Oxide Semiconductor Field-Effect Transistors at Higher Ge Content

In this work, it is shown that the maximum hole mobility of compressively strained Si1-xGex source-drain (S/D) p-MOSFETs is degraded after high-fluence 2 MeV electron irradiation, suggesting the loss of strain in the Si channel caused by the radiation-induced displacement damage. This is supported by the fact that the mobility reduction after irradiation is larger for SiGe S/D devices than for Si references at the same fluence (5 x 10(17) cm(-2)) and becomes more pronounced for shorter gate lengths. At the same time, however, it is found that the extent of mobility reduction becomes smaller for p-MOSFETs with a higher Ge content (35%, compared with 20 or 30%). Finally, it is concluded that, for shorter devices, the displacement-damage-related degradation mechanism becomes less pronounced with increasing Ge content in Si1-xGex S/D regions. (C) 2013 The Japan Society of Applied Physics