Local Mode Absorption in Compensated Silicon‐Doped Gallium Arsenide

摘要

Infrared‐active localized vibrational modes in lithium‐ and copper‐compensated silicon‐doped GaAs are reported. A number of absorption peaks due to both Si and Li are seen at liquid‐nitrogen temperature. The local mode of the Si donor, SiGa, occurs at ν=384 cm-1; the Si acceptor, SiAs, at 399 cm-1. Two bands at 374 and 393 cm-1, along with a component of the 384‐cm-1 band, are tentatively identified as the SiGa bands split by a Li (or Cu) acceptor. The three corresponding Li bands are seen near 450 cm-1 with 7Li and near 480 cm-1 with 6Li. For Li(Cu)‐Si‐doped GaAs a weak coupling model between Si‐Li or Si‐Cu ion pairs is proposed. This model has been previously proposed for Li‐B‐doped Si. Si concentration studies indicate that the strengths of the SiGa 384‐cm-1 and SiAs 399‐cm-1 bands are related more closely to the total Si concentration than to the carrier concentration. A number of additional and, at present, unexplained peaks are also observed.