Lyman spectrum of holes bound to substitutional 3d transition metal ions in a III-V host: GaAs(Mn²⁺, Co²⁺, or Cu²⁺), GaP(Mn²⁺), and InP(Mn²⁺)

Abstract

The 3d-transition metal impurities (Mn, Co, and Cu) incorporated into III-V zinc blende hosts (GaAs, GaP, or InP) exhibit well resolved excitation lines followed by a photoionization continuum in their infrared absorption spectra. They are associated with transitions from a "1s-like" ground state to various "p-like" excited states characteristic of a hole bound to a Coulomb center. Their spacings agree remarkably well with those predicted in the effective mass theory for single acceptors [A. Baldereschi and N. O. Lipari, Phys. Rev. B 9, 1525 (1974)] as expected for 3d-transition metal ions substitutionally replacing the group III cations of the host. The shape of the photoionization spectra, the occurrence of the simultaneous excitation of the Lyman transitions in combination with the zone center longitudinal optical phonon and hence lying in the photoionization continuum and displaying Fano-like asymmetries, the additional continuum excitations to and beyond the p_½; valence band maximum, are the features described and interpreted. Cu acceptors in GaAs show Lyman doublets, indicative of two independent centers; it is speculated that they could arise from He-like 3d¹⁰4s²4p¹, Cu^2-, and H-like 3d⁹4s²4p¹, Cu^-, Coulomb centers.