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This study demonstrates the emission enhancement of Al 3+ co-doped SrZn 2 (PO 4 ) 2 :Eu 2+ ,Mn 2+ phosphors. The crystallinity and emission mechanism were investigated, and the results indicate that co-doping with Al 3+ increased the atomic concentrations of Sr and P and induced the formation of Al–O bonds. The formation of P–O–P bonds was also facilitated. Furthermore, the crystal field strength of Mn 2+ –O 2- was decreased, and the reduction reaction of Eu 3+ to Eu 2+ was promoted. Photoluminescence measurements revealed a 2.83-fold enhancement of the Eu 2+ emission upon co-doping with 0.46 mol of Al 3+ . However, the Mn 2+ emission decreased and was blue-shifted because of the increased bond length of Mn 2+ –O 2- and decreased ligand field around Mn 2+ . The phosphor decay time was also reduced with increasing Al 3+ concentration.

The influence of In 3+ doping on the binding energy of ions and the energy transfer mechanism of white SrZn 2 (PO 4 ) 2 :Eu 2+ ,Mn 2+ phosphor was investigated. The ligand fields around Sr 2+ and Mn 2+ varied with different kinds of doped ions, while those around Zn 2+ and Eu 2+ remained stable. Doping with In 3+ created traps of charged species and clustered pairs in the phosphor. These traps captured excited carriers, leading to a decrease in energy transfer from Eu 2+ to Mn 2+ and a decline in Mn 2+ emission. However, carriers stored temporarily in traps then migrated to Eu 2+ to yield an enhanced Eu 2+ emission. The phosphor emission was blue-shifted by the increase in In 3+ concentration. Maximum Eu 2+ energy absorption and emission were obtained when doped with 12 mol% of In 3+ . The decay time of the phosphor was 11.74 ms.

Compound semiconductors doped with magnetically active transition metals (TM) are actively pursued for semiconductor spintronics. Herein we report that delta doping (δ-doping) has been used to incorporate manganese (Mn) into the gallium nitride (GaN) matrix resulting in phase pure highly crystalline heteroepitaxial thin films of (Ga,Mn)N on c-plane sapphire (Al2O3) by plasma-assisted molecular beam epitaxy. Magnetotransport measurements reveal the anomalous Hall effect (AHE) while magnetic measurements show the existence of ferromagnetic ordering. Density functional theory calculations show that δ-doping of Mn atom enables exchange interactions between the Mn 3d states and N 2p states thereby resulting in spin polarized holes in the valence band giving rise to observed AHE and ferromagnetism. This work opens new avenues for incorporating spin polarized carriers in III-nitrides based semiconductors by creating magnetically active Mn layers in heterostructures for spintronics applications.

When the phosphor LaPO4:Tm was coated with carbon nanotubes (CNTs), carbon atoms were diffused into the phosphor lattice. Binding energy of La 3d and C 1s were not shifted by CNT coating, while that of O 1s was lowered slightly as a result of the formation of C O and C O bonds on the phosphor surface. CNT coating increased the atomic concentrations of O and C by 27.4% and 9%, respectively. Photoluminescence intensity decreased significantly, by 52%, when CNT concentration of 1.5 wt% was coated. This is attributed to covering the phosphor with black CNTs/carbons and the formation of C O and C O bonds on the phosphor surface. Conversely, cathodoluminescence (CL) intensity was improved by a factor of 3.86 when 1.25 wt% of CNTs was coated, attributing to improved conductivity, reduced charging, and increased CL excitation probability of the phosphor. The influence of CNT coating on the luminescence of LaPO4:Tm was compared with that of LaPO4:Eu phosphor. Blue CL was observed from LaPO4:Tm, it is potential for field emission lamp application.