Conformable coating of SiO2 on hydrothermally grown ZnO nanorods

Abstract

Coating silicon dioxide on hydrothermally grown ZnO nanorods is demonstrated using a low temperature plasma enhanced chemical vapor deposition (PECVD) system. Wurtzite structured ZnO nanorods were prepared by spin coating ZnO nanocrystals onto plastics or glass substrates. Then, the nanorods were subsequently grown in a zinc nitrate solution. SiO2 was deposited by PECVD at 50 °C. No current could be measured through the patterned metal dots on the SiO2 coated sample, which indicates that SiO2 was covered seamlessly across the entire substrate. Photoluminescence measurements indicated that the SiO2 layer covering the nanorods did not alter the optical properties of the ZnO.

Randomly oriented, upright SiO2 coated nanorods for reduced adhesion of mammalian cells

“…1A, white arrows). Importantly, the SiO 2 coatings were deposited uniformly on each nanorod free of any local defects, which was confirmed with TEM, local electrical conductance measurements, chemical wet-etching and photoluminescence A intensity measurements [37]. Our technique thus resulted in randomly oriented, upright SiO 2 deposited nanorods that cover the surface with densely packed monolayers without any defects over cm length scales (Fig.…”

“…To arrest the nanorod growth, the substrates were removed from solution, rinsed with de-ionized water and dried in air at room temperature. SiO 2 was deposited with a Unaxis 790 plasma enhanced chemical vapor deposition (PECVD) system at 50 C using N 2 O and 2% SiH 4 balanced by nitrogen as the precursors as reported before [37]. Patterned nanorods were fabricated by conventional photoresist (PR) lithography [36].…”

“…Densely packed ZnO nanorods were fabricated with a low-temperature (95 C) hydrothermal, solution-based growth method [36]. We next deposited nano-thin films of SiO 2 with controlled thickness, 50 Å, using PECVD at 50 C according to our previously published methods [37]. Transmission electron microscopy (TEM) images of the resulting nanorods with 50 Å thickness of SiO 2 nano-films deposited are shown in Fig.…”

Reagent concentration dependent variations in the stability and photoluminescence of silica-coated ZnO nanorods

“…Again, however, there is little consistency regarding the consequences of such coatings, with different studies reporting enhanced ultraviolet (UV) band emission, enhanced visible-band emission, or unchanged emission intensities. [18][19][20][21] We have recently reported the fabrication of ZnO nanodot/ SiO 2 nanorod arrays by exposing thin (∼20-30 nm diameter) ZnO nanorods to a silica coating process. The thin nanorods evolve into ZnO nanodots during the coating process and the resultant composite ZnO nanodot/SiO 2 nanorods exhibit up to 2-fold enhanced UV emission efficiencies (along with a weak visible emission).…”

Arrays of nanorods composed of ZnO nanodots exhibiting enhanced UV emission and stability

“…[32][33][34][35] Previous studies have reported that SiO 2 -coated ZnO NRs display high sensitivity towards detecting ultraviolet (UV) photons 36 and biomolecules, 37 good UV-durable superhydrophobicity, 38 and enhanced UV emission. 39,40 Conversely, heterogeneous ZnO ND/SiO 2 structures reportedly show enhanced visible emission 41 but negative photoconductivity. 42 It may be relevant to note that in most such studies reported to date, the ZnO NDs were either embedded in bulk SiO 2 or individual silica-coated ZnO NDs were randomly distributed in solution.…”