Determination of nitrogen-acceptor spin-Hamiltonian parameters in ZnSe epilayers via spin-flip Raman spectroscopy

Resonant spin-flip Raman scattering measurements were performed for nitrogen-doped ZnSe grown on a (001)GaAs substrate by molecular-beam epitaxy. By tuning the excitation laser to resonance with the acceptor-bound exciton transition, spin-flip Raman scattering was observed between the spin states of the neutral nitrogen acceptors split by an external magnetic field. The spin-flip transitions exhibited strong magneto-optical anisotropy depending on the orientation of the magnetic field B with respect to the growth axis. The strain-induced splitting Δ between the light- and heavy-hole states was found to play an important role in the interpretation of the spin-flip Raman spectra. Specimens in which Δ is comparable to the Zeeman energies of the acceptor were chosen for study. In such specimens the parameters (Formula presented) and (Formula presented) in the spin-Hamiltonian terms (Formula presented) and (Formula presented) for the nitrogen acceptor, together with Δ itself, could be determined accurately by varying the field direction from [001] to [110] and, in the layer plane, from [110] via [010] to [1¯10]. The experiments give (Formula presented) and (Formula presented) and also demonstrate that accurate determination of the strain splitting Δ is possible for layers in which Δ is too small for the excitonic transitions involving the light- and heavy-hole states to be resolved by photoluminescence or by photoluminescence-excitation spectroscopy.