Characterization of defects in (ZnMg)Se compounds by positron annihilation and photoluminescence

Abstract

Photoluminescence spectroscopy and positron annihilation spectroscopy probe of alloying and annealing effects in nonpolar m -plane ZnMgO thin films Appl. Phys. Lett. 96, 151904 (2010);

Positron annihilation lifetime spectroscopy of ZnO bulk samples

“…Positrons are not well localized at the ionic traps and their wave functions extend to the bulk of the material; hence, the annihilation characteristics are similar to the delocalized state in the lattice and they get detrapped below room temperature. 12 The detrapping process from the ionic traps is thermally activated and the activation energy is equal to the binding energy E b . 13 The escape rate ͑␦ ion ͒ can be written as…”

Photoelectric and photothermal investigations of Zn1‐x‐yBexMnySe solid solutions

“…For this reason, determination of the energy gap from luminescence data is not possible for crystals with high Mn content. The band at 2.35 eV is observed only at low temperatures (and for low Mn content) and is probably associated with cation vacancy related defect level as it was shown for Zn 1-x Be x Se and Zn 1-x Mg x Se crystals by positron annihilation and luminescence techniques [16,17]. The intensity of this band decreases after annealing in zinc vapour at temperature 1230 K for two days.…”

Localization of excitons in Zn1−Mg Se and Cd1−Mg Se crystals

“…This indicates that this emission is due to radiative recombination of shallow donor-acceptor (D-A) pairs. From the positron annihilation experiment one can conclude that the next band (with maximum at about 2.2 eV for Zn 1−x Mg x Se with x = 0.06) can be attributed to some defects containing a cation vacancy [16]. For both, Zn 1−x Mg x Se and Cd 1−x Mg x Se crystals with x higher than about 0.3, the edge emission is not observed.…”