Giant dielectric constant in TiO2/Al2O3 nanolaminates grown on doped silicon substrate by pulsed laser deposition

Abstract

High quality amorphous nanolaminates by means of alternate Al2O3 and TiO2 oxide sublayers were grown with atomic scale thickness control by pulsed laser deposition. A giant dielectric constant (>10 000), strongly enhanced compared to the value of either Al2O3 or TiO2 or their solid solution, was observed. The dependence of the dielectric constant and the dielectric loss on the individual layer thickness of each of the constituting materials was investigated between 0.3 nm and 1 nm, in order to understand the prevailing mechanisms and allow for an optimization of the performances. An impedance study confirmed as the key source of the giant dielectric constant a Maxwell–Wagner type dielectric relaxation, caused by space charge polarization in the nanolaminate structure. The current work provides better insight of nanolaminates and their sublayer thickness engineering for potential applications.

Fabrication of highly homogeneous Al‐doped TiO2 nanotubes by nanolamination of atomic layer deposition

“…Recently, there has been a growing interest in fabricating advanced functional nanocomposites which display superior physical, chemical, or mechanical properties compared to their bulk constituents. The Al 2 O 3 –TiO 2 system has drawn extensive attractions because it has been widely used as a support material in the field of catalysis.…”

“…The Al 2 O 3 –TiO 2 system has drawn extensive attractions because it has been widely used as a support material in the field of catalysis. Modifying or stabilizing with the dopant of Al is regarded as an effective strategy for promotion of thermal stability, surface area, and porosity of TiO 2 . Besides, TiO 2 with the high dielectric constant (ĸ>40) and refractive index (n>2.4) has been considered as a promising material for the capacitor of dynamic random access memory (DRAM) .…”

Study on Structural, Mechanical, and Optical Properties of Al2O3–TiO2 Nanolaminates Prepared by Atomic Layer Deposition

“…13−17 Because of high thermostability and high optical transparency in the visible and ultraviolet spectra, these nanolaminates are especially useful for optical coatings. 18,19 Al 2 O 3 /TiO 2 nanolaminates have been prepared by many techniques, such as chemical vapor deposition, 20 pulsed plasmaenhanced chemical vapor deposition, 21 pulsed laser deposition, 22 and atomic layer deposition (ALD). 13−15,17−19 ALD is one of the most powerful methods for single layer and nanolaminates fabrication.…”

Kink effect in TiO 2 embedded ZnO quantum dot‐based thin film transistors

“…Researchers are trying to tune the high charge carrying capacitors by adding two different sorts of materials like Al 2 O 3 –TiO 2 as the dielectric system of the capacitor where Al 2 O 3 is used for reducing the leakage current while TiO 2 is for providing high‐ k [1]. Embedding a TiO 2 layer (T‐layer) in between two layers of Al 2 O 3 (A‐layer) may lead to a gigantic dielectric constant (>10 4 ) which is multiple times higher than the standalone dielectric constant of Al 2 O 3 and TiO 2 due to the introduction of Maxwell–Wagner type dielectric relaxation [3]. In this Letter, we have investigated the kink effect in a thin film transistor (TFT) fabricated by depositing an A–T–A (Al 2 O 3 –TiO 2 –Al 2 O 3 ) layer over a p‐Si substrate followed by the deposition of a layer of ZnO quantum dots (QDs) by the sol–gel method for acting as the charge transport layer of the TFT.…”