Photoneutralization of the Fe³⁺Centers in the ZnSe Crystals Heavily Doped with Iron

Abstract

Photoconductivity and optical quenching of the photoconductivity were measured. The photoneutralization of the Fe 3 + centres has been found to occur for photon energies down to 0.8 eV (i.e. the threshold can not be at 1.1 eV, as often quoted). The conclusion from our previous paper that the lattice relaxation energy is small, has been confirmed. It has to be smaller than 0.1 eV.PACS numbers: 71.55. Gs, 72.40.+w In ZnSe:Fe iron atoms substitute zinc and (speaking in the ionic language) in the Fee+ charge state they are neutral with respect to the lattice. The presence of the Fe3 + ( ionized) centres results from the compensation by shallow acceptors.In our previous paper on the iron centres in ZnSe [1] we have described the first observation of the photoionization of the Fee+ centres:and we have determined the optical ionization energy of the Fee+ centres at 77 K-2.1 eV ± 0.1 eV. As the thermal activation energy of the valence band -iron level transitions was found in the Hall effect measurements [2] to be 0.62 eV, and the energy gap at 77 K is 2.81 eV, we concluded that the lattice relaxation energy is small and the Fe2 +/3 + donor level in ZnSe is at 77 K both optically and thermally about 2.1 eV below the conduction band.(337)

Surface Photovoltage Spectroscopy of Cd0.97Fe0.03Se and Cd0.97Fe0.03Te Crystals

“…Also it was found that the position of the Fe+ 2 3d6 state is independent of temperature and iron concentration. This effect agrees with the results reported previously [3,6,8].…”

“…The electronic structure of those crystals is affected by the hybridization of s-p electrons with the localized 3d electrons and by created disorder stuctural, chemical and magnetic [1][2][3][4][5]. The Fe impurity in the wide-gap semiconduction CdSe and CdTe acts as deep donor state, located in the forbidden energy gap [6][7][8]. The influence of the Fe 3d state on the density of states dstribution in the valence band of these materials was a subject of several papers [2,4,5,7,8].…”

“…The Fe impurity in the wide-gap semiconduction CdSe and CdTe acts as deep donor state, located in the forbidden energy gap [6][7][8]. The influence of the Fe 3d state on the density of states dstribution in the valence band of these materials was a subject of several papers [2,4,5,7,8].…”

HgSe Based Mixed Crystals Doped with Fe Resonant Donors

“…Assuming that the Fermi level in these samples is pinned to the iron related resonant state and applying the Langer and Heinrich [8] ule, together with known (from the independent studies) energies of the Fe state in both end-compounds: HgSe and ZnSe (EFe = 0.2 eV above the bottom of the conduction band in HgSe [9]) and Eye 0.6-0.8 eV above the top of the valence band in ZnSe (Szadkowski et al [73] and Lubomirska-Wittlin et al [74]), the shift of Γ6 and Γ8 band edges upon alloying with Zn was deduced. .…”

Hopping Conductivity in (Zn,Fe)Se Intentionally Doped with Ag

“…In this material the Fe2 +/3 + donor level lies about 700 meV above the top of the valence band [5,6]. The as-grown crystals with iron content 0.6 at.% are semiinsulating.…”