Seed-Layer Free Zinc Tin Oxide Tailored Nanostructures for Nanoelectronic Applications: Effect of Chemical Parameters

Abstract

Semiconductor nanowires are mostly processed by complex, expensive, and high temperature methods. In this work, with the intent of developing zinc tin oxide nanowires (ZTO NWs) by low-cost and low-complexity processes, we show a detailed study on the influence of chemical parameters in the hydrothermal synthesis of ZTO nanostructures at temperatures of only 200 °C. Two different zinc precursors, the ratio between zinc and tin precursors, and the concentration of the surfactant agent and of the mineralizer were studied. The type and the crystallinity of the nanostructures were found to be highly dependent on the used precursors and on the concentration of each reagent. Conditions for obtaining different ZTO nanostructures were achieved, namely, Zn 2 SnO 4 nanoparticles and ZnSnO 3 nanowires with length ∼600 nm, with the latter being reported for the first time ever by hydrothermal methods without the use of seed layers. Optical and electrical properties were analyzed, obtaining band gaps of 3.60 and 3.46 eV for ZnSnO 3 and Zn 2 SnO 4 , respectively, and a resistivity of 1.42 kΩ·cm for single ZnSnO 3 nanowires, measured using nanomanipulators after localized deposition of Pt electrodes by e-beam assisted gas decomposition. The low-temperature hydrothermal methods explored here proved to be a low-cost, reproducible, and highly flexible route to obtain multicomponent oxide nanostructures, particularly ZTO NWs. The diversity of the synthesized ZTO structures has potential application in next-generation nanoscale devices such as field effect nanotransistors, nanogenerators, resistive switching memories, gas sensors, and photocatalysis.

Growth Mechanism of Seed-Layer Free ZnSnO3 Nanowires: Effect of Physical Parameters

“…The final product (white precipitate) comprising the nanostructures, was alternately washed with deionized water and isopropyl alcohol (at least 5 times) and centrifuged at 4000 rpm. After washed, the nanostructures were dried at 60 °C, in vacuum, for 2 h. As was previously reported [50], the syntheses present a good reproducibility, especially when using ZnCl 2 due its better solubility in ethylenediamine.…”

“…ZnSnO 3 nanowires were synthesized via hydrothermal method in a conventional oven, using the same methodologies and reagents reported previously by our group [50]. The most favorable chemical conditions to produce ZnSnO 3 nanowires previously obtained in [50] using tin (IV) chloride 5-hydrate (SnCl 4 ·5H 2 O) as tin precursor and both zinc chloride (ZnCl 2 ) and zinc acetate (Zn(CH 3 COO) 2 , ZnAc) as zinc precursors were maintained in this work.…”

“…ZnSnO 3 nanowires were synthesized via hydrothermal method in a conventional oven, using the same methodologies and reagents reported previously by our group [50]. The most favorable chemical conditions to produce ZnSnO 3 nanowires previously obtained in [50] using tin (IV) chloride 5-hydrate (SnCl 4 ·5H 2 O) as tin precursor and both zinc chloride (ZnCl 2 ) and zinc acetate (Zn(CH 3 COO) 2 , ZnAc) as zinc precursors were maintained in this work. Briefly the ZTO hydrothermal synthesis was performed by dissolving the zinc (0.02 M/0.0657 g of ZnAc or 0.04 M/0.0818 g of ZnCl 2 ) and tin (0.02 M/0.1050 g) precursors separately in 7.5 mL of deionized water and then mixed together, 7.5 mL of the surfactant ethylenediamine (EDA) were then added and left stirring for 30 min, after which the mineralizer sodium hydroxide (NaOH, 0.24 M/0.1450 g) was added.…”

“…Studies on the influence of chemico-physical parameters on the hydrothermal synthesis of ZTO have been reported, showing the possibility to control the shape and type of the nanostructures and consequently the electrical, optical, and mechanical properties [13,48,49]. Recently, we reported a thorough description of the influence of different hydrothermal synthesis’ chemical parameters in the growth of ZTO nanostructures [50]. This work was conducted without employing any seed-layer; hence, the obtained structures depend exclusively on the chemico-physical parameters of the synthesis.…”

“…In line with our previous work about the effect of the chemical conditions, this study is orientated towards the synthesis of ZTO nanowires, more specifically ZnSnO 3 , which properties allow to envisage application on numerous next-generation nanoscale devices such as nanogenerators [35,36,53], sensors [54,55,56], photocatalysis [57], solar cells [58], resistive switching memories [59,60], and transistors [22,29]. Moreover, we have previously shown that the structures synthetized using this hydrothermal method have properties that are similar to those produced by expensive and high-temperature methods [50], thus, being promising materials for a new wave of multifunctional and low-cost devices.…”