Radiation damage of Si1-xGex S/D p-type metal oxide semiconductor field effect transistor with different Ge concentrations

The 2-MeV electron radiation damage of Si1-xGex source/drain (S/D) p-type metal oxide semiconductor field effect transistor (p-MOSFET) with different Ge concentrations is studied. After irradiation at fluences below 2 × 1017 e/cm2, the drain current and the maximum hole mobility decrease with increasing electron fluence for all Ge concentrations. It suggests that lattice defects are introduced by electron irradiation. In the case of Si1-xGex S/D p-MOSFET, there are two locations for lattice defects, namely, the Si channel and SiGe stressor regions (S/D). Below 2 × 1017 e/cm2 irradiation, no clear correlation between the radiation degradation and Ge concentration has been observed. It suggests that this degradation is mainly due to lattice defects in the Si channel, and the effects of the compressive-strain induced by the SiGe stressors on the enhancement of the hole mobility still remains after irradiation at 2 × 1017 e/cm2. In the case of 5 × 1017 e/cm2 irradiation, the drain current drastically decreases after irradiation for all Ge concentrations. Moreover, after 5 × 1017 e/cm2 irradiation, the maximum hole mobility of x = 0.2 is close to x = 0, and in the case of x = 0.3, the maximum hole mobility drastically decreases. This fact suggests the contributions of the lattice defects, which are in the SiGe stressors, are prominent after 5 × 1017 e/cm2 irradiation and dependent on Ge concentration. In addition, it provides evidence that the compressive strain in the Si-channel is relaxed by high fluence electron irradiation.