Effect of Plasma-Enhanced Atomic Layer Deposition on Oxygen Overabundance and Its Influence on the Morphological, Optical, Structural, and Mechanical Properties of Al-Doped TiO2 Coating

Abstract

The chemical, structural, morphological, and optical properties of Al-doped TiO2 thin films, called TiO2/Al2O3 nanolaminates, grown by plasma-enhanced atomic layer deposition (PEALD) on p-type Si <100> and commercial SLG glass were discussed. High-quality PEALD TiO2/Al2O3 nanolaminates were produced in the amorphous and crystalline phases. All crystalline nanolaminates have an overabundance of oxygen, while amorphous ones lack oxygen. The superabundance of oxygen on the crystalline film surface was illustrated by a schematic representation that described this phenomenon observed for PEALD TiO2/Al2O3 nanolaminates. The transition from crystalline to amorphous phase increased the surface hardness and the optical gap and decreased the refractive index. Therefore, the doping effect of TiO2 by the insertion of Al2O3 monolayers showed that it is possible to adjust different parameters of the thin-film material and to control, for example, the mobility of the hole-electron pair in the metal-insulator-devices semiconductors, corrosion protection, and optical properties, which are crucial for application in a wide range of technological areas, such as those used to manufacture fluorescence biosensors, photodetectors, and solar cells, among other devices.

An Al-doped TiO2 interfacial layer for effective hole injection characteristics of quantum-dot light-emitting diodes

“…34 However, an opposite tendency occurred when ATO was deposited at a T dep of 250 1C, a typical deposition temperature for Al 2 O 3 /TiO 2 ALD processes with higher crystallinity. 35 According to a previous report, if the Al doping concentration is greater than 3%, corresponding to the R pc of 1/90, because the V o sites of the ATO are ruptured by the Al acceptor level, 36 the hopping conduction mechanism of the carriers injected from the ITO anode can be disrupted. From this point of view, a lower concentration of Al dopant was required in our experiment.…”

“…34 However, an opposite tendency occurred when ATO was deposited at a T dep of 250 °C, a typical deposition temperature for Al 2 O 3 /TiO 2 ALD processes with higher crystallinity. 35…”

The status and perspectives of nanostructured materials and fabrication processes for wearable piezoresistive sensors

“…ALD is a versatile technique that can be used to coat and functionalize surfaces with single or multiple components (Pessoa et al 2019 ). The foremost advantage of ALD is its ability to control the coating thickness down to the subnanometer range as a function of the number of reaction cycles (Chiappim et al 2021 ). ALD does not depend on the line of view to reach secluded spots; thus, it can be applied to almost any kind of high aspect ratio structures producing pinhole-free conformal coatings and chemically bonded layers by the use of sequential self-limiting surface reactions and low temperatures (Rodrigues et al 2019 ).…”

Preparation, Antimicrobial Properties under Different Light Sources, Mechanisms and Applications of TiO2: A Review

“…Atomic layer deposition (ALD) and magnetron sputtering (MS) methods are often used to prepare photocatalyst composite films. They can realize the doping [ 40 ] and deposition [ 41 , 42 ] of metal on photocatalysts or the loading of photocatalysts on other substrates [ 43 , 44 ], which can improve the optical properties of materials. The MS method is based on the principle of physical deposition, and the surface of the prepared film is flatter [ 45 ].…”