Centers of radiative and nonradiative recombination in isoelectronically doped ZnSe : Te crystals (original) (raw)

Mechanisms of radiative and nonradiative recombination in ZnSe:Cr and ZnSe:Fe

Low Temperature Physics, 2004

Possible applications of ZnSe:Cr in optoelectronics are discussed. It is shown that 2+ to 1+ photo-ionization of chromium results in efficient pumping of Cr 2+ intrashell emission and in energy up-conversion from green to blue. A distinct difference in efficiency of the energy up-conversion is observed between chromium and iron doped ZnSe samples. This difference we relate to a very efficient Auger mechanism of photoluminescence quenching in Fe-doped samples. We further demonstrate an anticorrelation of intensity of mid-infrared Cr emission and up-converted blue emission of ZnSe.

Preparation conditions of chromium doped ZnSe and their infrared luminescence properties

2001

We report the investigation by photoluminescence lifetime measurements of the near-IR emissions from a series of chromium-doped ZnSe samples, correlated to their preparation conditions. The samples were polycrystalline or single crystals prepared by post growth diffusion doping or single crystals doped during growth by the physical vapor transport method. Room temperature lifetime values between 6 and 8μs were measured for samples with Cr2+ concentrations from low 1017 to high 1018cm− 3 range.

Nonstoichiometry and luminescent properties of ZnSe crystals grown from melt and vapor

Journal of Crystal Growth, 2014

ZnSe homogeneity region was studied by direct physico-chemical method in 730-1320 K temperature range. It was established that the homogeneity region included stoichiometric composition and solidus lines both from Zn-and Se-rich sides demonstrated the retrograde behavior. Comparison of ZnSe nonstoichiometry with ionized defect concentrations at S ZnSe-L (Zn)-V equilibrium had let us assert that at the examined conditions the dominant point defects are electrically neutral. Nonstoichiometry analysis of ZnSe crystals grown from melt under high pressure and from vapor by the Markov-Davydov technique showed that there were Se-excess over stoichiometry in melt grown ZnSe and Zn-excess close to stoichiometry in vapor grown crystals.

Spectral structure of the X-ray stimulated phosphorescence of monocrystalline ZnSe

Physica B: Condensed Matter, 2015

This work presents the extensive experimental studies of the X-ray stimulated luminescence, conductivity, phosphorescence and electric current relaxation, and the thermally stimulated luminescence and conductivity of monocrystalline ZnSe. It was found that the luminescence emission band with a maximum at 635 nm is a combination of at least three emission bands and that the appropriate recombination centres implement both electronic and hole recombination mechanisms. We propose an energy model of the traps and recombination centres in monocrystalline ZnSe and show that the majority of the generated free electrons and holes recombine in the luminescence centres with an estimated probability of 94.3% and that only a small fraction (5.7%) of generated charge carriers are accumulated in traps during the X-ray excitation of the ZnSe sample.

Optical and EPR spectroscopy of Zn:Cr:ZnSe and Zn:Fe:ZnSe crystals

Optical Materials, 2014

Optical and EPR characterization of Cr and Fe doped ZnSe crystals annealed in Zn vapor revealed a strong bleaching of the divalent state of transition metal ions. Photo induced EPR kinetics were studied in 20-80 K temperature range. Analysis of time-dependent data reveals Cr 1+ signal rise time decreases with increasing temperature. The non-exponential decay of Cr 1+ concentration were analyzed using Augertype recombination process. The photoluminescence quantum yield of Cr 2+ ions at 5 E(D) ? 5 T 2 (D) mid-IR transition excited via chromium ionization process was measured to be close to 100%.

Luminescence study of ZnSe based scintillators in frequency domain

Lithuanian Journal of Physics, 2008

Photoluminescence of ZnSe-based scintillation crystals is studied. Photoluminescence intensities and spectra of isoelectronically doped ZnSe(Te), ZnSe(O), and ZnSe(O,Al) are compared. Frequency domain luminescence lifetime measurement technique was applied to study carrier dynamics at low density of nonequilibrium carriers, which is typical for operation of high-sensitivity ZnSe-based radiation detectors. Temperature-dependent competition between donor-acceptor-pair-type and exponential luminescence decay components was observed.

On the Absorption and Photoluminescence Properties of Pure ZnSe and Co-Doped ZnSe:Eu3+/Yb3+ Crystals

Applied Sciences

Co-doped Zinc selenide (ZnSe) is a promising material because of a high photoluminescence efficiency and wide spectral range emission in the visible region. In this work, ZnSe and Eu3+/Yb3+ co-doped ZnSe crystals were grown by the chemical vapour transport method. Photoluminescence and optical measurements revealed the effect of trivalent rare earth Eu3+/Yb3+ ions on the emission of new lines with enhancement intensity. In the photoluminescence spectrum, some sharp and intense lines were observed that allow for the possibility of covering a broad emission range. Moreover, the optical measurement showed a lower bandgap compared to that of pure ZnSe bulk crystal. This material is suitable for developing optoelectronic devices, which can emit light in the visible and near infrared range with an improved emission efficiency and wide tunability.

Luminescence dynamics in ZnSeTe scintillators

Journal of Luminescence, 2003

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. r