Photoluminescence of CuGaTeAs and CuGaSnGa complexes in n-GaAs under resonance polarized excitation

Photoluminescence (PL) of n-type GaAs:Te:Cu and GaAs:Sn:Cu with an electron density of about 10(18) cm(-3) was studied at 77 K. A broad band with a pe ak at the photon energy near 1.30 eV (GaAs:Te:Cu) or 1.27 eV (GaAs:Sn:Cu) w as dominant in the PL spectrum under interband excitation. This band arose from the recombination of electrons with holes trapped by CuGaTeAs or CuGaS nGa complexes. It has been found that the low-energy edge of the excitation spectrum of this PL band at photon energies below similar to1.4 eV is cont rolled by the optical ejection of electrons from a complex into the conduct ion band or to a shallow excited state. The PL polarization factors upon ex citation by polarized light from this spectral range suggest that the compl exes have no additional distortions caused by an interaction of a hole boun d at the center in the light-emitting state with local phonons of low symme try. This feature makes CuGaTeAs and CuGaSnGa complexes different from thos e with the Ga vacancy (V-Ga) instead of Cu-Ga. The dissimilarity arises fro m the difference in the intensity of interaction of a hole localized at the orbital of an isolated deep-level acceptor in the state corresponding to i ts pre-emission state in the complex (Cu-Ga(-) and V-Ga(2-)) with low-symme try vibrations of atoms. The perturbation of the hole orbital induced by th e donor in the complex practically does not affect this interaction. (C) 20 01 MAIK "Nauka/Interperiodica".