Effects Of Si Codoping Research Articles

Effect of Si codoping on thermoluminescence properties of undoped and RE (RE:Ce/Tb/Pr/Eu/Yb/Nd) doped YAG phosphor under UV, and γ-ray irradiation

The objective of this work is to test an efficient material synthesis method, for the development of thermoluminescence (TL) material using yttrium aluminium garnet. The TL properties of undoped, Ce/Tb/Pr/Eu/Yb/Nd doped Y3Al5O12 (YAG) polycrystalline material, synthesized by combustion synthesis at low temperature, under ultra-violet (uv) and γ -rays irradiation is reported. The effect of controlled Si codoping is also inspected. The introduction of the doping ions induces changes in the trapping processes and the TL efficiency. The TL signal of Ce doped YAG samples indicates a high sensitivity to uv, γ-ray irradiation. It has been found that there is a prominent enhancement in TL glow peak with Si doping. Trapping parameters of uv irradiated YAG:Ce/Si were calculated from the TL data. The prepared ceramics have found potential application for uv and γ−ray radiation dosimetry purpose.

Synthesis of Y3Al5O12:Tb & Y3Al5O12:Tb,Si phosphor by combustion synthesis: Comparative investigations on the structural and spectral properties

YAG:Tb polycrystalline powders have been prepared by combustion synthesis at low temperature. Structure and morphology of the obtained materials have been studied. Various structural parameters have been determined by X-ray powder diffraction measurements. Effect of Si codoping on structural and spectral properties have been compared. It has been shown that critical amount of Si found suitable for pure phase formation and enhancement in Tb3+ characteristics green emission in YAG.

Effects of Si Codoping on Optical Properties of Ce-Doped Ca6BaP4O17: Insights from First-Principles Calculations

It was recently reported that Ce-doped Ca6BaP4O17 displayed blue-green emission under excitation in the near-ultraviolet (UV) region and that luminescence intensities can be greatly improved by codoping with Si. Here, a combination of hybrid density functional theory (DFT) and wave function-based CASSCF/CASPT2 calculations at the spin–orbit level has been performed on geometric and electronic structures of the material to gain insights into effects of Si codoping on its optical properties. It is found that the observed luminescence arises from 4f–5d transitions of Ce3+ occupying the two crystallograhically distinct Ca1 and Ca2 sites of the host compound with comparable probabilities, with the energy of the lowest 4f → 5d transition of CeCa1 being slightly higher than that of Ceca2. The codopant Si prefers to substitute for the nearest-neighbor (NN) P1 atom over the NN P2 atom around Ce3+, and this preference induces a blueshift of the lowest-energy 4f → 5d transition, consistent with experimental observat...

Enhanced stability of Eu in GaN nanoparticles: Effects of Si co-doping

Ab initio calculations on Eu doped (GaN)n (n = 12, 13, and 32) nanoparticles show that Eu doping in nanoparticles is favorable compared with bulk GaN as a large fraction of atoms lie on the surface where strain can be released compared with bulk where often Eu doping is associated with a N vacancy. Co-doping of Si further facilitates Eu doping as strain from an oversized Eu atom and an undersized Si atom is compensated. These results along with low symmetry sites in nanoparticles make them attractive for developing strongly luminescent nanomaterials. The atomic and electronic structures are discussed using generalized gradient approximation (GGA) for the exchange-correlation energy as well as GGA + U formalism. In all cases of Eu (Eu + Si) doping, the magnetic moments are localized on the Eu site with a large value of 6μB (7μB). Our results suggest that co-doping can be a very useful way to achieve rare-earth doping in different hosts for optoelectronic materials.

The effect of Si co-doping on defect-induced intrinsic magnetism in GaN

Using the first principle method within the local spin density approximation,both the magnetism of defect induced in GaN and the effect of Si co-doping on the magnetism in GaN with defect were investigated.It was found that defect-induced intrinsic magnetic moment of GaN is 3μB,while the magnetic moment is quenched to 2μB in Si-co-doping GaN:Si.The magnetic moment decreases with the increase of the concentration of Si.The result is very helpful for experiments.

Effect of Si codoping on Eu3+ luminescence in GaN

Eu and Si codoped GaN thin films were grown on sapphire by solid source molecular beam epitaxy. Eu3+ photoluminescence (PL) emission at ∼622 nm (D50-F72) was enhanced by approximately five to ten times with Si doping. The effect of Si codoping on PL intensity, lifetime, and excitation dependence revealed two distinct regimes. Moderate Si doping levels (0.04–0.07 at. %) lead to an increase in lifetime combined with improved excitation efficiency and a greatly enhanced PL intensity. High Si doping levels (0.08–0.1 at. %) significantly quench the PL intensity and lifetime, due primarily to nonradiative channels produced by a high defect population.

Correlation of electrical and optical properties with charge collection efficiency of In-doped and In+Si co-doped CdTe

The effect of Si co-doping on electrical, optical and spectroscopic properties of In-doped CdTe was investigated. The concentration of Si atoms in the charge was 1×10 17 cm −3. All Si co-doped samples were n-types, with the resistivity higher than 1×10 9 Ω cm. The dominant deep level E D=0.67 eV was determined by temperature dependence of the Hall effect measurement and compared with the low-temperature photoluminescence. Cd-rich or Te-rich annealing was used to eliminate this deep level, which strongly affects the charge collection efficiency of samples. The deep level together with a poor charge collection efficiency were found in both as-grown or annealed Si co-doped samples contrary to samples with only In doping, where the detector quality improvement was observed after Te-rich annealing.

Effect of Si and Er Co-doping on Green Electroluminescence from GaN:Er ELDs

ABSTRACT(Er, Si) co-doped GaN thin films were grown on Si substrates by molecular beam epitaxy (MBE) technique. Electroluminescent devices (ELDs) were fabricated and the effect of Si co-doping on the performance of GaN devices was studied. Previous results with GaN:Er ELDs reported that electroluminescence (EL) was much stronger in reverse bias than in forward bias condition, indicating that the dominant factor in EL intensity was the electric field. The results reported here show the first time GaN:Er ELDs where forward bias EL is very much larger, indicating that the dominant factor is forward bias current. The electrical properties of (Si, Er) co-doped GaN thin films are believed to be responsible for the current control mechanism.