A study was made of the possibility of generating complexes of Fe and P atoms. Neutral interstitial Fe atoms at various concentrations were measured in P-doped crystals, by using the electron spin resonance method, after cooling from high temperatures at various cooling rates. This concentration was found to depend upon the cooling rate when the P concentration was high: The concentration of interstitial Fe was low only when the P concentration was high and the cooling rate was low. This showed that some Fe atoms formed complexes with P atoms during cooling, and became electron spin resonance-inactive. The annealing behavior of these complexes, with regard to the concentration of neutral interstitial Fe, was attributed to a combination of 2 processes. These were the release of Fe atoms from Fe-P complexes, and the diffusion of Fe to quenched-in defects. The latter were deduced to exist on the basis of the dependence of the annealing behavior upon the cooling rate. By analyzing the annealing behavior, the binding energy between Fe and P atoms, and the activation energy for Fe diffusion, were estimated to be 0.90 and 0.80eV, respectively.

H.Takahashi, M.Suezawa, K.Sumino: Journal of Applied Physics, 1995, 78[5], 3077-82