Radiation Effects on Si:P and SiGe:P Alloys: Electrophysical and Mechanical Characteristics

The scope of the study is to investigate the microstructure, electrophysical properties, and amplitude-dependent behavior of internal friction and shear modulus in phosphorus-doped monocrystalline n-Si and n-Si+0.5 at.% Ge alloy, both in their initial state and after irradiation with 60Co-gamma photons. Additionally, the regularities of changes in critical strain amplitude will be examined. Metallographic study showed that the dislocation density on the (111) crystallographic planes of the samples range from 104 to 5×104 cm–2. Irradiation by 60Co gamma photons does not cause significant changes in the density and distribution of dislocations. It was established that in test n-Si sample gamma photons irradiation increases the electrical resistivity by 15-20%, reduces the concentration of current carriers by 8-10 times, and increases their mobility by 1.5-times. Such changes were relatively weakly detected in the tested SiGe alloy. Under conditions of torsional oscillation frequencies of 0.5-5.0 Hz and strain amplitude of 10-5 to 5×10-3 at room temperature, an increase in critical strain amplitude by 15-20% was determined in irradiated samples. The effect of radiation hardening was more clearly observed in the n-Si+0.5 at.% Ge alloy. The possible mechanisms of changes of physical-mechanical characteristics have been analyzed. Established regularities in the changes of electrical and physical-mechanical characteristics in Si-Ge alloys irradiated by gamma photons can be applied in the development of radiation-stable, high-efficiency semiconductor devices.