Characterization of structural defects in MBE grown ZnSe

On the basis of low temperature photoluminescence structural defects in molecular beam epitaxy (MBE) grown ZnSe are identified. We investigate a series of ZnSe samples, in which the layer thickness has been varied from 50 up to 4300 nm. The photoluminescence of the Y0 line at an energy of 2.61 eV shows a degree of linear polarization up to 80% with respect to an 〈110〉 axis indicating a strong internal distortion preferentially aligned collinear to one of the four 〈110〉 axes. Excitation of the line is possible for different photon energies below the band gap. The photoluminescence excitation spectra is dependent sensitively on the detection wavelength of the monochromator. The very narrow Y0 line exhibits a fine structure of five subcomponents at zero magnetic field. The Zeeman-effect of the Y0 line is investigated. A strong anisotropy of the Zeeman-splitting is observed. In Faraday-configuration ( B → ∥ 〈 001 〉 ) the effective g-factor is geff = 0.7 .2 and the two magnetic subcomponents are shifted towards lower energies. The Y0 line is interpreted as an excitonic recombination associated with dislocations.