INFLUENCE OF GERMANIUM CONTENT ON THE DEGRADATION OF STRAINED SI1-XGEX EPITAXIAL DIODES BY ELECTRON-IRRADIATION

The degradation of strained n+-Si/p+-Si1-xGex epitaxial diodes, which arc irradiated at room temperature with 1 MeV electrons in a high-volt age transmission electron microscope, is investigated. Special attenti on is given to the influence of the germanium content on the degradati on of electrical characteristics and on the introduction of lattice de fects into the epitaxial layer. The diode degradation and the deep lev el density for the x = 0.12 diodes are larger than for the x = 0.16 di odes. This can be explained by the fact that germanium atoms act as re combination centres for vacancies and interstitials thus decreasing th e generation rate of stable radiation defects and by the fact that the energy absorbed in the epitaxial layer during irradiation decreases w ith increasing germanium content due to the smaller stopping power of germanium atoms.