Three-Step Growth of Well-Aligned ZnO Nanotube Arrays by Self-Catalyzed Metalorganic Chemical Vapor Deposition Method

Abstract

We have successfully synthesized vertically aligned ZnO nanotube arrays by metalorganic chemical vapor deposition. Since no metal catalysts are used in this work, the growth process of ZnO nanotube arrays does not follow a vapor-liquid-solid mechanism but a self-catalyzed growth mechanism. X-ray diffraction results show that the nanotubes have ZnO hexagonal wurizite structures and only the ZnO (0002) peak can be seen. The rocking curve also shows a full width at half-maximum value of similar to 1625 arc second. A 6-fold symmetry in phi-scan data is also observed, indicating in-plane alignment of ZnO nanotube arrays. Room temperature photoluminescence results present a high optical quality and nearly defect-free crystal structure of ZnO nanotube at-rays. Moreover, the high near-band edge emission to deep level emission intensity ratio (I(NBE)/I(DLE)) of 2050 is obtained

The Effect of Geometric Structure on Photoluminescence Characteristics of 1-D TiO2Nanotubes and 2-D TiO2Films Fabricated by Atomic Layer Deposition

“…As observed in Figure 8, TiO 2 nanotube arrays with 700 deposition cycles showed higher absorbability but lower PL intensity, whereas TiO 2 nanotube arrays with 200 deposition cycles had lower absorbability but higher PL intensity. According to the investigation of Wu et al 35 on the PL spectra of ZnO nanorods and nanotubes, the tubular structure is advantageous to the optical characteristic because of the higher porosity and larger surface area. Therefore, even though both volume and surface area affect the performance of PL, when the trend of these two factors contradicts with each other, surface area dominates the performance of PL.…”

“…The reason most likely stems from the fact that the surface area represents a discontinuity of atomic arrangement. Larger surface has higher number of surface defects thus higher number of oxygen vacancies [30][31][32][33]35,36 that can contribute to higher intensity for the PL spectrum. Figure 9 shows the Gauss fitting of PL spectra of TiO 2 nanotube arrays with 200, 300 and 700 deposition cycles.…”

MOCVD of ZnO Films from Bis(Ketoiminato)Zn(II) Precursors: Structure, Morphology and Optical Properties

“…[42,43] At variance with most literature data, no PL signals due to deep level emission (DLE) defects (V o , V Zn , Zn i , and O i ) in the region 420 -540 nm could be detected. [17,18,[20][21][22][23]25,[44][45][46][47] …”

Ultraviolet sensing based on nanostructured ZnO/Si surface acoustic wave devices

“…The dominant UV emission at 389 and 390 nm can be assigned to the exciton recombination, which suggestes that the ZnO film and NRs possess a good crystallinity [32]. A few weak emission peaks in the region between 420 and 540 nm were also detected, which are attributed to the presence of point defects such as oxygen vacancies and zinc interstitials [33,34]. The presence of the defects indicates that the ZnO film and NRs are slightly oxygen-deficeient.…”