Stability of Tensile-Strained Ge Studied by Transmission Electron Microscopy

The sensitivity of strained Ge to damage after irradiation with 300kV electron-beam was studied. A time-dependent damage analysis under TEM irradiation on two 0.5 μm-width waveguides, one with 1 GPa stress and a 20 nm protection layer, the other with 2 GPa stress but no protection layer, was performed. The interface for highly-strained waveguides was severely damaged by e-beam within mere seconds, and the damage propagated into the deeper region with time. For the weakly strained sample, the weak damage was confined within 2 nm of the interface and did not propagate. Highly strained Ge interfaces were susceptible to damage, and the dislocations propagated deep into the waveguide.