Characterization and Field‐Emission Properties of Vertically Aligned ZnO Nanonails and Nanopencils Fabricated by a Modified Thermal‐Evaporation Process

Abstract

Vertically aligned ZnO nanonails and nanopencils are synthesized on a silicon substrate using a modified thermal‐evaporation process, without using a catalyst or predeposited buffer layers. An adiabatic layer is used to provide an abrupt temperature decrease and high gas concentration for the nanostructures growth. The structure and morphology of the as‐synthesized ZnO nanonails and nanopencils are characterized using X‐ray diffraction, and scanning and transmission electron microscopies. Raman and photoluminescence properties are also investigated at room temperature. Field‐emission characterization shows that the turn‐on fields for the vertically aligned ZnO nanonails and nanopencils are 7.9 and 7.2 V μm–1, respectively.

Assembling ZnO Nanorods into Microflowers through a Facile Solution Strategy: Morphology Control and Cathodoluminescence Properties

“…The UV emission peak of the microflowers in this work is 388 nm, which is in good agreement with the typically reported free exciton peak position and could be attributed to UV near-band edge emission [39]. The impurities and structural defects, such as oxygen vacancies and so forth, are responsible for the deep level or trap-state emission in the visible range [40]. For the visible green emission peaks in CL spectrum, it is generally accepted that the green emission originates from the radiative recombination of a photogenerated hole with an electron occupying the oxygen vacancy [41][42].…”

“…ZnO, as an important semiconductor material, has a wide variety of applications in pigments [16], field effect transistors [17], field emitters [18], ultraviolet detectors [19], cosmetics [20] and energy storage [21][22][23]. To date, various splendid morphologies of ZnO nanostructures have been reported by different synthesis approaches including thermal evaporation [24][25][26], hydrothermal reaction [27][28][29], electrochemical deposition [30][31].…”

Integration of ZnO Nanotubes with Well-Ordered Nanorods through Two-Step Thermal Evaporation Approach

“…21 From Figures 3d and 4c, it is clear that no additional metal particles or tiny nanocrystals appear on the top of the nanorods, ruling out the possibility of the catalysis process during the growth of well-aligned ZnO nanorods. 21,22,27 On the other hand, the growth rate along the dislocation line in the screw dislocation model is much higher than that along the radius direction, resulting in the crystal 1-D structure morphology. 21,28,29 The conic tip with spiral morphology at the end of 1-D structured materials is the evidence that screw dislocation mechanism manifests itself.…”

Growth and characterization of ZnO needles

“…Various methods, such as precipitation (Lee et al 2002), sol-gel (Rani et al 2008), vapor-liquid-solid (VLS) growth (Ham et al 2005), chemical vapor deposition (CVD) (Zeng and Ye 2005), thermal decomposition (Zhao et al 2007), metal organic vapor-phase epitaxy (Li et al 2000), have been developed for controlling ZnO structures, since its various properties strongly depend on its structures including the crystal size, orientation, morphology, aspect ratio and even crystalline density. Currently, many interesting ZnO nanostructures including nanorods (Lucas and Mai 2007), nanowires (Xiang et al 2007), tetrapods (Chen et al 2007), nanocombs (Li et al 2008), nanotubes (Anas and Mangalaraja 2010), nanopencils (Shen et al 2006) and star-like (Peng et al 2010) have been successfully synthesized. In this letter, we presented a simple vapor-phase transport method approach to fabricate ZnO needles.…”