Infrared absorption by pairs of group III and V impurities in silicon

Infrared absorption bands, shifted to regions of lower energies relative to narrow lines of transitions of impurities to excited states, are investigated in silicon doped with group III and V impurities in concentrations above 10(16) cm(-3). It is found that the band structure is peculiar to each of the investigated impurities but independent of their concentrations, and the absorption coefficients in the bands increase approximately quadratically with concentration. This leads one to infer that the bands are caused by the excitation of charge carriers bound on impurity pairs localized within several Bohr radii. (C) 2002 MAIK "Nauka / Interperiodica".