Effect of impurities on the growth of {113} interstitial clusters in silicon under electron irradiation

Abstract

The growth and shrinkage of interstitial clusters on {113} planes were investigated in electron irradiated Czochralski grown silicon (Cz-Si), floating-zone silicon (Fz-Si), and impurity-doped Fz-Si (HT-Fz-Si) using a high voltage electron microscope. In Fz-Si, {113} interstitial clusters were formed only near the beam incident surface after a long incubation period, and shrank on subsequent irradiation from the backside of the specimen. In Cz-Si and HT-Fz-Si, {113} interstitial clusters nucleated uniformly throughout the specimen without incubation, and began to shrink under prolonged irradiation at higher electron beam intensity. At lower beam intensity, however, the {113} interstitial cluster grew stably. These results demonstrate that the {113} interstitial cluster cannot grow without a continuous supply of impurities during electron irradiation. Detailed kinetics of {113} interstitial cluster growth and shrinkage in silicon, including the effects of impurities, are proposed. Then, experimental results are analyzed using rate equations based on these kinetics.

Keywords:

• Czochralski grown silicon
• floating-zone silicon
• point defect
• interstitial cluster
• irradiation damage
• electron irradiation
• impurity

Acknowledgement

The authors wish to express their most sincere gratitude to the late Professor Michio Kiritani. Without his support, encouragement and physical insight, our work would not have been possible.