Enhancement of the intensity ratio of ultraviolet to visible luminescence with increased excitation in ZnO nanoparticles deposited on porous anodic alumina
Enhancement of the intensity ratio of ultraviolet to visible luminescence with increased excitation in ZnO nanoparticles deposited on porous anodic alumina
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DOI：
10.1088/0022-3727/46/50/505104
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发表时间：
2013-12-18
影响因子：
3.4
通讯作者：
Ferid, Mokhtar
中科院分区：
文献类型：
--
作者：
Bousslama, Wiem;Sieber, Brigitte;Ferid, Mokhtar
多孔阳极氧化铝（PAA），具有大的孔径（高达100 nm），被用作ZnO纳米结构的生长基板。几乎无应变的ZnO纳米粒子的尺寸小于8 nm的制备通过旋涂法和退火在500摄氏度激子复合被发现占主导地位的紫外波段。ZnO纳米颗粒在低激发下具有高的深能级发射，其在高激发下变得可忽略不计，如从光致发光测量推断的。这种紫外-可见光发光比随激发的大幅增加归因于紫外和可见光发光随激发强度的变化。非辐射俄歇复合在高激发下占主导地位。它也表明，PAA衬底提高了通过溶胶-凝胶法实现的ZnO纳米粒子的内量子效率。在低激发下，发光强度在13和300 K之间下降3倍，导致内部量子效率估计高达30%。
Porous anodic alumina (PAA), with large pore diameters (up to 100 nm), was used as a substrate for the growth of ZnO nanostructures. Almost unstrained ZnO nanoparticles of less than 8 nm in size were prepared by the spin-on method and annealed at 500 degrees C.Excitonic recombination is found to dominate the ultraviolet band. The ZnO nanoparticles have a high deep level emission at low excitation which becomes negligible at high excitation, as deduced from photoluminescence measurements. This large increase of the ultraviolet to visible luminescence ratio with excitation is ascribed to the variation of the ultraviolet and of the visible luminescence with excitation intensity. Non-radiative Auger recombination becomes dominant at high excitation. It is also shown that the PAA substrate improves the internal quantum efficiency of the ZnO nanoparticles achieved by the sol-gel method. At low excitation, the luminescence intensity drops by a factor of 3 between 13 and 300 K, leading to an estimate of the internal quantum efficiency as high as 30%.