Measurement of electrical resistance of metals and silicon under laser irradiation

Iwamoto, Yosuke   ; Wakai, Eiichi  ; Nakagawa, Yuki*; Shibayama, Tamaki*

In order to develop a new non-destructive inspection technique to accurately measure defects inside materials in radiation fields such as nuclear power plants, accelerators, and aerospace, we have measured the time evolution of electrical resistivity of copper, aluminum, and niobium metal wires and silicon plates by irradiating a pulsed laser beam (20 Hz) at Hokkaido University. From the obtained increase in electrical resistivity, the number of atomic vacancies and Frenkel pairs (FPs) of interstitial atoms and the dislocation density of the formed FPs were estimated, assuming that the atoms were ejected by the laser due to electronic excitation. From this experiment, it was estimated that for metals, the amount of defects formed inside the material increased with the increase in the irradiation dose. On the other hand, for silicon, the electrical resistivity was found to decrease due to the electronic transition to the valence band caused by laser irradiation.