Electrical activation and electron spin resonance measurements of   implanted bismuth in isotopically enriched silicon-28
  We have performed continuous wave and pulsed electron spin resonance measurements of implanted bismuth donors in isotopically enriched silicon-28. Donors are electrically activated via thermal annealing with minimal diffusion. Damage from bismuth ion implantation is repaired during thermal annealing as evidenced by narrow spin resonance linewidths (B_pp=12uT and long spin coherence times T_2=0.7ms, at temperature T=8K). The results qualify ion implanted bismuth as a promising candidate for spin qubit integration in silicon. 
C. D. Weis, C. C. Lo, V. Lang, A. M. Tyryshkin, R. E. George, K. M.   Yu, J. Bokor, S. A. Lyon, J. J. L. Morton, T. Schenkel
cond-mat.mtrl-sci