Donor-H complexes

In the study by Johnson et al. (1986) it was shown by Hall effect measurements that the sheet carrier density was decreased and the mobility was increased for a thin w-type layer following exposure to a hydrogen plasma at 150°C. To explain the mobility increase it was argued that donor-H complexes were formed and that the concentration of ionized scattering centers was thereby decreased. On the basis of semiempirical calculations, a structural model was suggested for the donor-H complex in... 

Fig. 9. IR absorption bands in P-, As-, and Sb-doped Si samples that had been passivated in an H2 plasma. The sharp bands to the left are assigned to H-stretching modes of the donor-H complexes. The spectra were recorded near liquid He temperature. [Reprinted with permission from The American Physical Society, Bergman, K., Stavola, M., Pearton, S.J., Lopata, J. (1988), Phys, Rev. B 37, 2770.]... 

When the samples were etched mildly, the anomalous increase upon annealing was not observed. In an isothermal annealing experiment performed at 423 K for As—H complexes, the exponential decay given by Eq. (3) was verified for a 50 times reduction in concentration. In Fig. 11 the results of a series of 30 min isochronal anneals are shown for each of the donor-H complexes. The curves are given by Eq. (3) with an assumed attempt frequency of 1013 s-1 and binding energies of 1.32 eV for P—H and 1.43 eV for As—H and Sb—H. 

The assignment of the 809 and 1560 cm-1 bands of the donor-H complexes were based upon the expected frequencies of the wagging and stretching modes and the 2 1 ratio of intensities (Bergman et al., 1988a). A uniaxial stress study of the vibrational bands (Bergman et al., 1988b) will be reviewed here. Only the As—H complex was studied under stress because the donor-H complexes have nearly identical vibrational spectra for the different donors and are expected to behave similarly under stress. 

---