In contrast to common visible emission, an anomalous near-infrared emission at 790 nm has been demonstrated in spinel structure MgGa2O4:Mn2+ with heavy Mn2+ doping.

Room-temperature green to orange color-tunable upconversion is achieved from Yb3+/Mn2+ co-doped CaO by adjusting the doping concentration of Mn2+ ions upon 980 nm diode laser excitation.

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In this paper, the degradation behavior of the electrical characteristics was investigated, and trap analysis based on low-frequency noise (LFN) was carried out for the commercial 1.2-kV/30-A silicon carbide (SiC) power MOSFETs under repetitive short-circuit (SC) stress. The experiment results show that the on-state resistance (R dson) and threshold voltage (V th) increase significantly. Meanwhile, the drain-source current (I ds) decreases obviously with the increase of the SC cycles. Furthermore, the gatesource leakage current (I gss) of the SiC power MOSFETs increase greatly and the blocking characteristics deteriorated after 1000 SC cycles. The positive shift was observed on the gate-capacitance versus gatevoltage (C g-V g) curve, which shows that the damage region could be in channel along the SiC/SiO 2 interface after repetitive SC stress. In order to obtain the trap information, trap characterization was performed by using LFN method, and the LFN results show that the trap density increases with the SC cycles. The physical mechanism could be attributed to electrically active traps generated at SiC/SiO 2 interface and oxide layer due to the peak ionization rate, the perpendicular electrical field and high temperature during SC stress. The study may be useful to provide reference for converters design and fault protection of SiC power MOSFETs. INDEX TERMS Repetitive short-circuit (SC), low-frequency noise (LFN), traps, silicon carbide (SiC) power MOSFETs.

A series of Ca3La3(1-x)Eu3x(BO3)5 phosphors were prepared via a solid-state reaction under reducing atmosphere. Rietveld refinements were performed by adopting the powder X-ray diffraction data, which indicates the occupations of Eu3+ on both La3+ and Ca2+ sites with a preferred location on the La3+ site over the Ca2+ site. This kind of phosphors could be excited by UV and blue LED in solid-state lighting technology and the CIE chromaticity coordinates for phosphors CLBO: 0.06Eu3+ (λex = 254 nm) and CLBO: 0.12Eu3+ (λex = 393 nm) are (0.6712, 0.3328) and (0.6685, 0.3287), respectively, which are compliant with the national television system committee (NTSC) standard for red chromaticity. The energy transfer rate between the Eu3+-Eu3+ pairs is weak that proved by the results of the decay process and the efficiency of the Eu3+ 5D0→7F2 emission. The mechanism responsible for the non-reduction of Eu3+ was analyzed, which was determined by two factors: 1) no element of the host matrix can be oxidized and 2), cationic vacancies which can be regarded as the electron donor cannot exist. The temperature dependence study shows thermal quenching behavior is attributed to crossover from the 5D0 excited state of the Eu3+ to the charge transfer state band and these phosphors have good thermal stability.