Surface Plasmons Enhancement Of Photoluminescence From Zinc Oxide By Aluminum Nanoparticles

During the past few decades,surface plasmons?SPs?has become a research hotspot.SPs are the collective oscillations of free electrons at the interface between metal and dielectric surrounding.Localized surface plasmon resonance?LSPR?for metal nanoparticles?NPs?has wide application on the light emission enhancement by the selective photon absorption and enhanced local electromagnetic fields.Nowadays,many achievements of SP-enhanced-emissions have been applied to light emitting diodes?LEDs?.With the advantage of direct wide band gap?3.37 eV?and large exciton binding energy?60meV?,zinc oxide?ZnO?,which is considered as a potential material,has a wide range of applications,especially on ultraviolet?UV?optoelectronic devices.However,the low photoluminescence efficiency of ZnO limited commercial applications of ZnO-devices.Related research shows that the selection of different metal NPs,such as Platinum?Pt?,Aluminum?Al?,Argentum?Ag?,Aurum?Au?,is one of the approaches to improve the UV emission from ZnO.In this letter,two-dimensional arrays of Al NPs were used to improve the localized surface plasmon resonance?LSPR?photoluminescence efficiency from ZnO grown by atomic layer deposition?ALD?.Two-dimensional arrays of Al NPs were fabricated on the substrates of p-type Gallium nitride?GaN?by colloid lithography.With air-liquid interface self-assembly,the monolayer masks for colloid lithography were obtained on substrates of p-type GaN.Then,after that a 50 nm Al layer was deposited by thermal evaporation,the Al NPs arrays were gained by dipping into toluene and extra sonication to remove the masks.Finally,15 nm Al₂O₃ and 200 nm ZnO films were deposited in sequence by ALD at a temperature of 125 ^oC.The extinction spectra of Al NPs arrays were acquired by ultraviolet-visible spectrophotometer.The results of the extinction spectra suggested that the radiative recombination rate was increased by the resonance coupling between the localized surface plasmons?LSPs?of the Al NPs arrays and the excitons of the ZnO.A 1.91-fold enhancement of photoluminescence integral intensity in near-band-edge emission was measured because of the Al NP arrays coupled with ZnO.The result means the LSP of the Al NPs arrays can increase the UV-emission of the ZnO.Therefore,this cost-effective and facile approach can be used in high performance optoelectronic devices.