Angle-resolved studies of the spin-flip Raman scattering of holes bound to acceptors in p-type nitrogen-doped zinc selenide

Studies of resonant spin-flip Raman scattering by holes bound to neutral nitrogen acceptors in layers of epitaxial zinc selenide grown by metallo-organic vapor phase epitaxy are presented. Earlier work on one such sample yielded preliminary values for the spin-Hamiltonian parameters of the nitrogen acceptor but did not address the question of the role of strain in the spectra. Those measurements have now been extended: the reproducibility of the signals in other similar samples has been established and the strain state of the samples has been determined. In order to investigate the states involved in the Raman scattering process in more detail, the spin-flip Raman scattering spectra were recorded as a function of the angle between the normal to the ZnSe layer and the direction of the magnetic field. The results show a clear anisotropy of the spin-flip Raman signals, hence confirming that they are indeed due to carriers in states related to the valence band and, furthermore, indicating clearly that the strain splitting of the light- and heavy-hole valence-band states (of around 1 meV, depending on the layer thickness) does play an important role in these samples. A model for the angle dependence of the signals is presented that describes the observed behavior and allows the spin-Hamiltonian parameters for the nitrogen acceptor to be investigated. The spectra also show signals arising from the simultaneous spin flips of an electron and a hole.