Occupation site change of self-interstitials and group-III acceptors in Si crystals: Dopant dependence of the Watkins replacement efficiency
We studied the dependence of the Watkins replacement efficiency on the species of group-III impurities from the measurement of the concentration of IH2, a complex of one self-interstitial (I) and two H atoms. If the IH2 concentration depends on species of group-III impurities under the same irradiation dose, the smaller concentration means a greater replacement efficiency. Specimens were prepared from floating-zone-grown Si crystals and Czochralski-grown Si crystals doped with B, Al, Ga, and In. After hydrogenation, they were irradiated with 3-MeV electrons at room temperature. We measured the optical absorption of those specimens. The IH2 concentration was found to depend on the B concentration, becoming smaller as the B concentration became larger. It also depended on the species of group-III dopants. Hence the replacement efficiency of I and group-III impurities depended on the concentration and species of group-III dopants.