ZnSe Scintillators Research Articles

Effect of post deposition annealing on thermal evaporated ZnSe:Te towards a scintillator application

ZnSe having a wide but direct bandgap (bulk band gap 2.7eV) is very efficient for detecting nuclear radiations by using its scintillation property. With a high absolute light output and radiation spectra which match well with Si-photodiode spectral sensitivity, ZnSe scintillators have adequately minimized the gap between “scintillator-photodiode” series for modern radiation detectors. Promising features like long decay time and high values of intrinsic radiation absorption make ZnSe based scintillators a very interesting research filed. Here in this report, we investigate an inexpensive and easy method to realize ZnSe:Te film on a quartz substrate. ZnSe:Te film is deposited using a thermal evaporator using ZnSe and ZnTe powders as raw materials to start with. After the deposition, the samples are exposed to a thermal annealing step for 1h. The temperatures are kept at 624, 674 and 724K. We have confirmed presence of a preferred [111] oriented polycrystalline ZnSe:Te thin films by XRD experiments. Photoluminescence experiment using a He:Cd laser at 324nm at low temperature (8K) reports an emission at 2.54eV due to non-equilibrium carrier plasma.

Luminescence in ZnSe scintillation crystals co-doped with oxygen and aluminum

Zinc selenide scintillation crystals isoelectronically doped with aluminum and oxygen by introducing Al2O3 into the charge were grown, and their emission was studied under photo- and X-ray- excitation, and comparison of their emission properties to those of the conventional scintillator ZnSe(Te) was accomplished. It is demonstrated that this technique for oxygen introduction enables the formation of oxygen-related deep donor–acceptor pairs (DAPs) acting as radiative recombination centers in ZnSe(O,Al) up to the densities exceeding the density of the corresponding Te-related DAPs in ZnSe(Te) at the doping level of 1wt%. ZnSe(O,Al) exhibits a higher photoluminescence intensity than that in ZnSe(Te) because of more efficient light absorption, while the photoluminescence quantum yield and the emission intensity under X-ray excitation show an opposite trend.

Emission properties of ZnSe scintillation crystals co-doped by oxygen and aluminum

Photoluminescence properties of ZnSe scintillation crystals co-doped with oxygen and aluminum are studied together with conventional tellurium-doped ZnSe scintillators, for comparison, under continuous-wave and pulsed excitation in the temperature range from 8 to 300K. A strong enhancement of the low-energy component in the deep-level-related emission is observed as the temperature approaches the room temperature. Fitting of the experimentally observed luminescence decay with calculations of the decay due to donor–acceptor pair recombination revealed that the increased density of recombination centers is responsible for the enhanced low-energy emission component in the co-doped crystals. The significant thermal enhancement of this spectral component is explained by carrier detrapping from the trapping centers abundant in the co-doped crystal due to a large concentration of aluminum impurities.

Characterization of ZnSe(Te) scintillators by frequency domain luminescence lifetime measurements

Dynamics of photoluminescence (PL) decay in Te-doped ZnSe scintillator crystal is studied using frequency domain luminescence lifetime measurement technique, which enables simultaneous characterization of components in multicomponent PL decay in a wide time window ranging from millisecond to nanosecond domain. Evolution of decay times and relative contributions of the decay components corresponding to different PL decay mechanisms was revealed as a function of temperature.

Luminescence dynamics in ZnSeTe scintillators

ZnSeTe single crystals with 2 wt% of Te fabricated for application as scintillating material in radiation detectors are studied by means of photoluminescence spectroscopy. Time evolution of the luminescence spectra, which is found to be strongly dependent on thermal treatment in different environments, reveals competition between nonradiative recombination and channels of radiative recombination resulting in two strongly overlapping emission bands. The origin of the bands is interpreted by recombination involving defect complexes containing Zn vacancies. Stabilization of the complexes by doping ZnSe with isoelectronic Te is discussed. Influence of annealing in Zn on reduction of concentration of nonradiative recombination centers and stabilization of the defect complexes, which are employed in ZnSe scintillation detectors, is demonstrated.

On some properties peculiar to Caoutchouc, and their aplications

Photoluminescence properties of ZnSe scintillation crystals co-doped with oxygen and aluminum are studied together with conventional tellurium-doped ZnSe scintillators, for comparison, under continuous-wave and pulsed excitation in the temperature range from 8 to 300 K. A strong enhancement of the low-energy component in the deep-level-related emission is observed as the temperature approaches the room temperature. Fitting of the experimentally observed luminescence decay with calculations of the decay due to donor–acceptor pair recombination revealed that the increased density of recombination centers is responsible for the enhanced low-energy emission component in the co-doped crystals. The significant thermal enhancement of this spectral component is explained by carrier detrapping from the trapping centers abundant in the co-doped crystal due to a large concentration of aluminum impurities.