Solution-Grown Zn/Al Layered Double Hydroxide Nanoplatelets onto Al Thin Films: Fine Control of Position and Lateral Thickness

Abstract

We have grown nanostructured films of Zn/Al Layered Double Hydroxide (LDH) on different substrates by combining the deposition of an aluminum micropatterned thin layer with a successive one-step room-temperature wet-chemistry process. The resulting LDH film is made of lamellar-like nanoplatelets mainly oriented perpendicular to the substrate. Since the aluminum layer acts as both reactant and seed for the synthesis of the LDH, the growth can be easily confined with submicrometric-level resolution (about ±0.5 μm) by prepatterning the aluminum layer with conventional photolithographic techniques. Moreover, we demonstrate real-time monitoring of the LDH growth process by simply measuring the resistance of the residual aluminum film. If the aluminum layer is thinner than 250 nm, the morphology of LDH nanoplatelets is less regular and their final thickness linearly depends on the initial amount of aluminum. This peculiarity allows accurately controlling the LDH nanoplatelet thickness (with uncertainty of about ±10%) by varying the thickness of the predeposited aluminum film. Since the proposed growth procedure is fully compatible with MEMS/CMOS technology, our results may be useful for the fabrication of micro-/nanodevices.

Characteristics, Preparation Routes and Metallurgical Applications of LDHs: An Overview

“…Moreover, and very important, is the fact that the surface can be patterned to form a circuit with a thin layer of the sacrificial metal to support the growth of LDH. Integrated sensors and devices could take great advantage from this technique [33].…”

Surface spectroscopy and structural analysis of nanostructured multifunctional (Zn, Al) layered double hydroxides

“…A wide range of synthesis techniques can prepare (Zn, Al) LDH crystallites, because of their typical shape of nanosheets. Among these, we can mention the simple one‐step hydrothermal process at room temperature, in which one can use Zn salt precursors on Al sputtered thin substrates, or Al foils . In this case, the metal substrate (Al) acts as a support and reactant (forming a reservoir for the trivalent M 3+ cation).…”

Layered Double Hydroxides: Tailoring Interlamellar Nanospace for a Vast Field of Applications

“…Moreover, in principle it enables the deposition of LDH films to any surface, provided a thin layer of the reacting metal covers the surface. Most importantly, the surface can be patterned with the thin metal layer so as to form printed circuits with tracks and pads supporting the growth of LDH, which could be very useful for integrated sensors and devices [33]. On the other hand, so far it is still to be demonstrated a good control of the composition and morphology of the deposited film.…”

“…Those studies were mainly addressed applications of LDHs as anticorrosion coatings or functionalized electrodes for electrical batteries and capacitors. More recently, our group has demonstrated that controlled films can also be grown an aluminum thin films, which were previously sputtered or evaporated on any surface [33,107]. In this way, LDHs films made of lamellar-like nanoplatelets, can be grown selectively on specific areas, with submicrometric-level resolution (about ±0.5 m), by prepatterning the aluminum layer with conventional photolithographic techniques (Figure 3).…”