Effects of specimen preparation on the cathodoluminescence properties of ZnO nanoparticles

Abstract

To establish a reliable procedure for the characterization of luminescence from nanomaterials, the cathodoluminescence ͑CL͒ observation conditions, such as the packing density of particles and the electron beam energy for irradiation, were examined by using ZnO nanoparticles. The evolutions of the intensities and peak position with the accelerating voltage are strongly affected by the packing density of particles. For the low-density specimen, the band edge emission reaches a maximum at 4 kV where the excitation of each nanoparticle becomes the most effective. On the other hand, the position of band edge emission does not shift for low-density specimen while it changes for high-density specimen. Such artifact may bring serious modifications to the CL data. This work suggests that the specimen preparation and the optimum excitation conditions are the keys for the reliable CL characterization of nanomaterials.

Depth-resolved cathodoluminescence study of zinc oxide nanorods catalytically grown on p-type 4H-SiC

“…Accelerating voltage is considered as a main parameter is affecting the electron beam [21]. Therefore, the depth dependent CL spectra were investigated.…”

Unipolar assembly of zinc oxide rods manifesting polarity-driven collective luminescence

“…After the structural and chemical examinations, spatially resolved CL measurements on individual ZnO assemblies were carried out. CL spectra were collected with a high-resolution CL system at 10-kV accelerating voltage and at a constant current density of 2,000 pA at room temperature, by using Ultra-High Vacuum SEM and a Gemini electron gun (Omicron) equipped with a CL system (32). The vacuum of the specimen chamber was maintained at 10 −11 mbar.…”

Low-energy cathodoluminescence microscopy for the characterization of nanostructures

“…As an example, we have investigated two samples of the same material having dissimilar concentration of nanoparticles [19]. Different weights of commercial ZnO nanoparticles were dispersed in 5 ml of ethanol to prepare a 'low-density' sample with small segregation and 'high-density' sample with significant agglomeration of particles.…”

“…The studied samples were rare-earth doped oxynitride phosphors (Ca and Yb codoped α-SiAlON and Eu-doped AlN) synthesized by gas-pressure sintering [9][10][11][12][13][14] [17,18], nanoparticles (vapor method) [19], nanoflowers (hydrothermal method) [20], tetrapods composed of nanorods (catalyst-free vapor-solid growth) [21], polycrystals [22] and single crystals (hydrothermal synthesis) [23].…”