Contribution of strain effects toward the damage measured in semiconductors by channeling

Abstract

Channeling measurements are reported which determine the radial distribution of defects, across the 〈111〉 and 〈110〉 channels, created by 20–40 keV He⁺, N⁺ and Zn⁺ bombardments of Si, GaAs and GaP at 50 K. Also the damage vs. dose data are reported for the above systems and for heavier ions, both monatomic and diatomic. The results of both sets of measurements are correlated into a consistent model in which the channeled beam backscatters off the grossly displaced atoms and small atom relaxations due to strains necessary to accommodate the damage. It is shown that at low damage levels (≲10%) the channeling technique accurately determines the number of displaced atoms, N _D, but at higher damage levels, interactions with the relaxed atoms will result in an over-estimate of N _D. The degree of over-estimation increases as Z₁ decreases and dominates for very low Z₁ ions. A model is developed which adequately fits the damage vs. dose behavior in which the strain-induced component is assumed proportional to N _D.