Effect of anionic group [SiO4]4−/[PO4]3− on the luminescence properties of Dy3+-doped tungstate structural compounds

Novel scheelite structures of Li2Ca(WO4)2, Li2Ca2(WO4)(SiO4), and LiCa2(WO4)(PO4) fluorescent materials were successfully prepared using a high-temperature solid-phase process. The compounds were characterized by X-ray diffraction and energy dispersive spectroscopy. The tests revealed that the substitution of [WO4]2− by [SiO4]4− or [PO4]3− tetrahedron in tungstate had no significant influence on the crystal structure of the Li2Ca(WO4)2. When Dy3+ ions were introduced as an activator at an optimum doping concentration of 0.08 mol%, all of the as-prepared phosphors generated yellow light emissions, and the emission peak was located close to 576 nm. Replacing [WO4]2− with [SiO4]4− or [PO4]3− tetrahedron significantly increased the luminescence of the Li2Ca(WO4)2 phosphors. Among them, the LiCa2(WO4)(PO4):0.08Dy3+ phosphor had the best luminescence properties, decay life (τ = 0.049 ms), and thermal stability (87.8%). In addition, the as-prepared yellow Li2Ca(WO4)2:0.08Dy3+, Li2Ca2(WO4)(SiO4):0.08Dy3+, and LiCa2(WO4)(PO4):0.08Dy3+ phosphor can be used to fabricate white light emitting diode (LED) devices.

Effect of Anionic Group [SiO4]4-/[PO4]3- on the Luminescence Properties of Dy3+-Doped Tungstate Structural Compounds

The novel scheelite structures of Li2Ca(WO4)2 , Li2Ca2(WO4)(SiO4), and LiCa2(WO4)(PO4) fluorescent materials were successfully prepared using a high-temperature solid-phase method. The compounds were characterized by XRD, EDS, and XRF. The test results showed that the substitution of [WO4]2- by [SiO4]4- /[PO4]3- tetrahedron in tungstate had no significant influence on the crystal structure of the Li2Ca(WO4)2. When Dy3+ ions were introduced as an activator at an optimum doping concentration of 0.08% mol, all of the as-prepared phosphors generated yellow light emissions, and the emission peak was located close to 576 nm. Replacing [WO4]2- with [SiO4]4- /[PO4]3- tetrahedron significantly increased the luminescence of the Li2Ca(WO4)2 phosphors. In addition, the LiCa2(WO4)(PO4):zDy3+ phosphors had the best luminescence properties, decay life (τ = 0.049 ms), and thermal stability (87.8%).

Preparation and spectroscopic properties of Ca2MgTeO6:Tm3+ blue-emitting tellurate phosphors

Various novel Ca2MgTeO6:Tm3+ blue-emitting tellurate materials were synthesized via solid-state reaction. The structure and phase purity of prepared Ca2MgTeO6:xTm3+ (x = 0.0025-0.10 mol) were examined by X-ray powder diffraction. The Ca2MgTeO6:Tm3+ phosphors emit blue emission at 359 nm excitation. The optimum doping concentration was 0.02 mol. The concentration quenching mechanism in the Ca2MgTeO6 host was due to the electric dipole-dipole interaction. The The CIE chromaticity coordinates of Ca2MgTeO6:Tm3+ phosphors located in the blue region. These results validated the Ca2MgTeO6:Tm3+ tellurate phosphor can be used as good blue-emitting candidate for W-LEDs.

Synthesis and luminescence properties of CaLaMgNbO6:Mn4+ red phosphor for UV-based w-LEDs

A series of [Formula: see text] ([Formula: see text] = 0.0005, 0.001, 0.003, 0.005, 0.007, 0.009) phosphors were prepared by traditional solid-state method at high temperature. The structure and morphology of the samples were analyzed. The results showed that the prepared [Formula: see text] [Formula: see text] phosphors were uniformly dispersed and the particle size was less than 5 [Formula: see text]m. [Formula: see text] phosphors have the strongest excitation peak at 351 nm, which is caused by the [Formula: see text] transition of [Formula: see text] ions. The strongest emission peak is at 697 nm, which is due to the [Formula: see text] level transition of [Formula: see text]. The optimum doping concentration is 0.5 mol.% and the mechanism of concentration quenching is the dipole–dipole interaction between [Formula: see text] ions. Importantly, [Formula: see text] sample has good thermal stability ([Formula: see text]/[Formula: see text] = 48.3%). In addition, the color coordinates of all samples were concentrated in the far-red region (0.733, 0.267). The above results indicate that [Formula: see text] sample has potential application value in the field of white light-emitting diodes ([Formula: see text]-LEDs).

Preparation, Structure, Optical and Morphological Properties of Co, Ga2O3 Co-Doped ZnS/Se

The material of doping transition metal (TM) in chalcogenide compound such as ZnS and ZnSe can be used in sensors, nonlinear optics, optical thin-films and mid-infrared area because of their faster optical response time, wider transparency range of mid-infrared and higher mid-infrared transmittance, low optical loss and phonon energy. In this paper, the ceramic targets of (ZnS/Se)0.4(Co)x(Ga2O3)0.6-x(x=0.1, 0.3 and 0.5) were prepared by high temperature solid state reaction. The mass loss rate, shrinkage rate and molar ration were calculated. XRD, absorption spectrum and AFM&OM were investigated. All of the results are shown that the optimum doping concentration is (ZnS/Se)0.4(Co)0.5(Ga2O3)0.1(namely x=0.5), and the optimum intering temperature are in the range 1000~1200°C. Besides, the zinc-blende structure on ceramics targets was confirmed by XRD. A broad application range from VIS to Mid-infrared was suggested by absorption spectra. The optimal base material ZnSe was proved by AFM and OM. All these results indicate that bulks of (ZnS/Se)0.4(Co)x(Ga2O3)0.6-xare most promising materials in future

Preparation and Luminescence Properties of Dy3+ Doped Sr3Lu(PO4)3 as a New Single Phase White Light Emitting Phosphor

The novel white light emitting phosphors Sr3Lu(1-x)Dyx(PO4)3 (x = 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized via a conventional high-temperature solid-state reaction method at 1250°C. The excitation spectrum indicated that these phosphors had a strong absorption in near UV region in the range from 260 to 460 nm. And under 350 nm excitation, the blue emission at 483nm (4F9/2→6H15/2) and yellow emission at 576 nm (4F9/2→6H13/2) were observed in the phosphors, respectively. We studied the effect of different doping concentrations of Dy3+ activator on the luminescence properties and found that the optimum doping concentration is 6 mol%. According to the Dexter’s theory, this quenching behavior is ascribed to be electric d-d interaction. Furthermore, the chromaticity coordinate (x = 0.28, y = 0.32) of Sr3Lu (PO4)3:0.06Dy3+ phosphor was very close to the “ideal white” (x = 0.33, y = 0.33) in the chromaticity diagram. Our results indicate that the Sr3Lu (PO4)3:Dy3+ phosphor can serve as a promising candidate for single-component white light emitting phosphor under near UV excitation.

Conduction Loss Reduction for Bipolar Injection Field-Effect-Transistors (BIFET)

In this study, the potential of forward conduction loss reduction of Bipolar-Injection Field-Effect-Transistors (SiC-p-BIFET) with an intended blocking voltage of 10kV by adjusting the doping concentration in the channel-region is analyzed. For the optimization of the SiC-p-BIFET, numerical simulations were carried out. Regarding a desired turn-off voltage of approximately 25V, the optimum doping concentration in the channel-region was found to be 1.4x1017cm-3. Based on these results, SiC-p-BIFETs were fabricated and electrically characterized in the temperature range from 25°C up to 175°C. In this study, the differential on-resistance was found to be 110mΩcm2 for a temperature of 25°C and 55mΩcm2 for a temperature of 175°C. In comparison to our former results, a reduction of the differential on-resistance of about 310mΩcm2 at room temperature is demonstrated.

A Comparative Study of Spin Coated Transparent Conducting Thin Films of Gallium and Aluminum Doped ZnO Nanoparticles

Transparent conducting Ga:ZnO (GZO) and Al:ZnO (AZO) layers have been deposited by spin coating on glass substrates using crystalline nanoparticles redispersed in 1-propanol. The coatings have been sintered in air at 600°C for 15 min and then postannealed in a reducing atmosphere at 400°C for 90 min. The effect of Ga and Al doping on the structural, morphological, optical, and electrical properties of the obtained thin films was investigated. Both films were found to be crystalline with a hexagonal structure. A single step spin coated layer 52–56 nm thick is obtained. To increase the thickness and lower the obtained sheet resistance multilayers coatings have been used. The visible transmission of both layers is high (T>80%). The influence of the sintering temperature and the optimum doping concentration was investigated. Five layers synthesized with doping ratio of 1 mol.% and sintered at 600°C and then submitted to reducing treatment in forming gas exhibited a minimum resistivity value of 7.4 × 10−2 Ω·cm for GZO layer and 1.45 Ω·cm for AZO coating.

Recent Research Progress of Long-wavelength Emitting Long-persistent Luminescence Materials

Blue and Green long-persistent luminescence materials have been fully developed, and are well featured in production and application. However, long-wavelength emitting materials are very rare relatively. This paper presents some work from our laboratory on the recent progress in long-wavelength emitting long-persistent luminescence materials: Sr3Al2O5Cl2: Eu2+, Tm3+, Sr2SnO4: Sm3+ and Ca2BO3Cl: Eu2+, Dy3+. The initial intensity of Sr3Al2O5Cl2: Eu2+, Tm3+ can reach nearly 5000 mcd/m2 and its afterglow can last about 220 min at recognizable intensity level. Sr2SnO4: Sm3+ has a red emission and its afterglow time of which sintered in vacuum atmosphere increased substantially. With optimum doping concentration and sufficient excitation with UV light, the yellow afterglow of Ca2BO3Cl: Eu2+, Dy3+ can persist over 48 h.

THE IMPACT OF CHANNEL ENGINEERING ON SHORT CHANNEL BEHAVIOR OF NANO FIN-FETs

This short note presents the simulation result on the effect of channel engineering i.e., non-uniform channel doping on short channel effects (SCE) in nano Fin-FET devices using Silvaco TCAD tool. The nano Fin-FET structures were generated using DEVEDIT and the effect of channel doping concentration has been studied. The optimum doping concentration profile has been observed to considerably improve the SCE in general and drain induced barrier lowering (DIBL) in particular.