Doped ZnSe Crystals Research Articles

Resonance interaction between plasmons and two-phonon states in ZnSe crystals

Raman spectra of doped ZnSe crystals with the carrier densities n = 10 17 to 10 18 cm −3 have been investigated. It is found that the new intensitive peak appears in the spectra in the case when the plasmon-phonon frequency L + falls within the region of two-phonon states. The frequency corresponding to this peak varies with carrier density. This fenomenon is explained by the anharmonic coupling of plasmon and two-phonon excitations.

Acceptor centers in phosphorus doped ZnSe crystals

Phosphorus doped ZnSe crystals, prepared by melt growth techniques under conditions to enhance the incorporation of phosphorus as a uncompensated acceptor, show two broad luminescence bands at 1.91 and 1.15 eV. Excitation bands resolved from the band edge absorption are found for both emissions. Electron paramagnetic resonance has established the atomic structure of two photosensitive P-centers: isolated P substitutional for Se, denoted by PSe, and clusters of 4 ions. PSe centers are seen their trigonally distorted paramagnetic charge state at 1.3°K before exposing the crystal to light. The crystal behaves electrically as partially compensated high resistivity material where the dominant trap is the PSe acceptor, which acts as sensitizing center for the observed n-type photoconductivity. Infrared quencing with a low energy edge at ≈0.6 eV of photoconduction, of 1.91 eV photoluminescence, and of the PS e paramagnetic resonance; and dark conductivity with an activation energy of ≈ 0.7 eV establish this behavior and provide a tentative relationship between the PS e center and the 1.91 eV luminescence. Similar results are obtained in As doped ZnSe.

Synthesis and melt growth of doped ZnSe crystals

Single crystals of ZnSe have been grown by the gradient freeze technique from a stoichiometric melt in a sealed hot-walled system. This allows the incorporation of dopants of high vapor pressure and maintainance of stoichiometry. Samples are subsequently shown not to be entirely self-compensated.