Gate-Length Dependent Radiation Damage in 2-MeV Electron-Irradiated Si_1-xGe_x S/D p-MOSFETs

The effect of 2-MeV electron irradiation of Si1-xGexS/D p-MOSFETs with different gate length and Ge concentration is studied. After electron irradiation, the maximum hole mobility decreases with increasing electron fluence for all gate lengths. In particular, after 5 x 1017e/cm2irradiation, the maximum hole mobility drastically decreases at short channel region for x = 0.3. Furthermore, a negative shift of the threshold voltage is clearly observed. These degradations can be explained both by the lattice defects and the stress relaxation in the Si channel created by atomic displacements.