Conduction mechanism of metal-TiO2–Si structures

doi:10.1016/j.cjph.2016.08.011

Chinese Journal of Physics

Volume 55, Issue 1, February 2017, Pages 59-63

https://doi.org/10.1016/j.cjph.2016.08.011 Get rights and content

Highlights

•
Rutile films were prepared on Si substrates by magnetron sputtering of TiO₂ target.
•
The current-voltage and capacitance-voltage characteristics were measured over T = 283–363 K.
•
The conduction model has been proposed for metal-TiO₂–Si (MIS) structures.

Abstract

The conduction model has been proposed for the metal-TiO₂–Si (MIS) structures. Rutile films have been prepared on Si substrates by magnetron sputtering of TiO₂ target and annealing in the air at temperatures T = 800 and 1050 K. The current-voltage (CVC) and capacitance-voltage characteristics of the structures have been measured over the range of T = 283–363 K. At positive potentials on the gate, the conductivity of the MIS structures is determined by the space charge-limited current in the dielectric layer.

Introduction

Functional oxide thin films are of great importance in modern micro- and nanoelectronics, including metal-insulator-semiconductor (MIS) structures [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13]. Titanium oxide films can be used as the key elements in different electronic devices such as memristors, photovoltaic cells, transparent electrodes and gas sensors. A breakthrough in the development of silicon microelectronic is associated with an increased informative capacity that can be achieved by replacing traditional SiO₂ on dielectrics with high dielectric permitivity ε. One of the possible candidates for the role of an alternative dielectric is a titanium oxide with a band gap of E_g = (3.0–3.2) eV and ε = 30–80 depending on the structure and phase composition. In the present study, the conduction mechanism is evaluated in metal-TiO₂–Si structures.

Section snippets

Experimental methods

Titanium oxide film, with thickness d = 70 nm, were prepared by magnetron sputtering on a silicon epitaxial layer with donor concentration N_d = 7×10¹⁴ cm⁻³. The TiO₂ ceramic disc was used as a target for sputtering. The sample preparation details can be found elsewhere [14], [15], [16]. After titanium oxide deposition, the Si substrate with the dielectric film was divided into several parts. One part was not subjected to annealing and two parts were annealed in the Ar atmosphere for 30 min at T_a

Results and discussion

As deposited titanium oxide films are amorphous. According to XRD spectra, the sample annealed at 800 K possesses a combination of the amorphous phase background and low intensity diffraction peaks. The peaks match well those of the PDF card (No.:43–1012) and can be revealed at 2θ = 25.2°, 27.4° and 56.7° which belong to crystallites of anatase and rutile, as shown in Fig. S1. After annealing at 1050 K, the amorphous phase disappears, and the film becomes polycrystalline rutile (Fig. S2). Thus,

Summary

The influence of annealing temperature of TiO₂ films on the currents in metal-TiO₂–Si structures was investigated. Regardless of the annealing temperature, the conductivity of the structures at positive potentials on the gate is determined by the space charge-limited current in the dielectric. At negative potentials, the current-voltage characteristics are explained by the thermal generation of electron-hole pairs in the space charge region of Si. The properties of TiO₂–Si interface strongly

Acknowledgment

This work was supported by the Ministry of Education and Science of the Russian Federation (Project No 3.1206.2014).

References (20)

C.V. Ramana et al.
Appl. Surf. Sci.
(2007)
V.A. Shvets et al.
J. Non Cryst. Solids
(2008)
V.V. Atuchin et al.
Opt. Mater.
(2008)
V.H. Mudavakkat et al.
Opt. Mater.
(2012)
V.V. Atuchin et al.
Mater. Lett.
(2013)
J. Robertson
J. Appl. Phys.
(2008)
C.V. Ramana et al.
Appl. Phys. Lett.
(2008)
V.M. Kalygina et al.
Semiconductors
(2010)
V.V. Atuchin et al.
J. Vac. Sci. Technol. A
(2011)
V.M. Kalygina et al.
Semiconductors
(2011)

There are more references available in the full text version of this article.

Cited by (18)

From hexafluorotitanate waste to TiO<inf>2</inf> powder: Characterization and evaluation of the influence of synthesis parameters by the experimental design method
2022, Advanced Powder Technology
Citation Excerpt :
It is widely used in sun screens because of its UV absorbing properties and its transparency. Moreover, as a photocatalyst, TiO2 has proved to be useful for a wide variety of environmentally friendly applications, such as microelectronics, solar cells, air and water purification, and has shown self-cleaning and antibacterial properties [1–7]. However, nature does not yield TiO2 in a form suited to our exploitation of its specific properties.
This paper was focused on the possible chemical synthesis routes to obtain titanium dioxide, TiO₂, from hexafluorotitanate waste and it was aimed to identify the parameters affecting the formation of crystalline titanium dioxide, TiO₂, phases (anatase or rutile). An experimental design method, inspired from the Taguchi approach, was used to assess the positive or negative impact of input factors on the formation of rutile and anatase, which were the output factors of interest. An experimental matrix was built up with coded values for each factor and coefficients were computed to point out a correlation between outputs and inputs. Particular attention was paid to the chemical compounds (decomplexing agents) added to precipitate TiO₂ from hexafluorotitanates and to the dehydration temperature used to obtain TiO₂ crystallized phases. The powders resulting from the syntheses were investigated by X-Ray diffraction analysis. Their chemical compositions were determined by Inductively Coupled Plasma Atomic Emission Spectroscopy. Data-matching revealed the best synthesis conditions in terms of crystallized TiO₂ content, and this was confirmed by calculating the processing yields. The results showed that silica and calcium hydroxide were the most efficient decomplexing agents leading to the formation of anatase.
Investigation of electrical and capacitance- voltage characteristics of GO/TiO<inf>2</inf>/n-Si MOS device
2020, Materials Science in Semiconductor Processing
In this paper electrical analysis GO/TiO₂/Si MOS junction was performed. Current–voltage (I–V) characteristics of diode were analyzed at 298–398 K. Several parameters such as ideality factor (η), barrier height ( $φ_{B}$ ), rectification ratio (RR), series and shunt resistances (R_S& R_sh) were estimated from I–V plots. The results showed that the MOS junction obeyed the thermionic emission phenomenon. In addition, capacitance – voltage (C–V) were measured at voltage range (−2Vto+2 V), at temperature range of (233–363 K) and at different frequencies. At low frequency 10 Hz revealed that negative capacitance of capacitor. A negative capacitance is due to an inductive behavior of studied materials. Moreover, at higher frequency, f = 2 × 10⁷ Hz, capacitance increases slightly with the increase of temperature and the interface states (Nss) cannot pursue ac signal and gives the geometrical capacitance values.
Plasmonic hybrid platinum-titania nanocomposites as highly active photocatalysts: Self-cleaning of cotton fiber under solar light
2020, Journal of Materials Research and Technology
Citation Excerpt :
As a vital semiconductor material, titanium dioxide or titania (TiO2) nanomaterials have been extensively studied. Good physical and chemical properties combined with high stability in acidic and alkaline solutions make it the most popular semiconductors [1–13]. It has been classified as one of the most considered nano-compounds in materials science for its photocatalytic efficiency.
In the present paper, a one-step, simple, efficient and low-cost strategy was demonstrated for preparing of highly stable hybrid platinum-titania (Pt@TiO₂) photocatalyst by solvothermal wet chemical process. Platinum (Pt) in the metallic form combined with titania (TiO₂) in the crystallographic anatase form has been manufactured using Dimethyl Sulfoxide (DMSO) as a solvent and surfactant using titanium (IV) butoxide and hydrogen hexachloroplatinate(IV) precursors. Full characterization of the hybrid nanomaterials including their morphology, crystalline structure and optical properties was determinate using different experimental techniques such as XRD, TEM and UV–vis spectroscopy. TEM images showed spherically shaped Pt nanoparticles (NPs) of the diameter 5–10 nm with good particle size distribution. The EDXRF data revealed that Pt NPs are in metallic form. Optical investigation show that Pt@TiO₂ NPs exhibits a good optical response under UV–vis light excitation compared to bare-TiO₂. Furthermore, photocatalytic investigation of Pt@TiO₂ colloids photocatalyst towards the photodegradation of diuron, as a model organic pesticide was reported. The hybrid Pt@TiO₂ photocatalyst prove high-performance on the photodecomposition of the pesticide under solar light within only 60 min. In the other hand, the plasmonic hybrid Pt@TiO₂ was incorporated into the cotton fabric to attain a modified fiber with high self-cleaning activity.
Micromixing-assisted preparation of TiO <inf>2</inf> films from ammonium hexafluorotitanate and urea by liquid phase deposition based on simulation of mixing process in T-shaped micromixer
2019, Ceramics International
Citation Excerpt :
Over the past several decades, numerous research activities have been focused on fabrication of TiO2 films owing to their broad applications in various fields such as air purification, wastewater treatment, electronic structures, solar cells and corrosion protection of metal [1–6].
Preparation of well-ordered TiO₂ films from alkaline solution by liquid phase deposition (LPD) method is still challenging owing to the fact that, in traditional mixing process, several disadvantages exist in controllable homogenous chemical reactions. In this contribution, mixing process in a porous dispersed double T-junction micromixer was designed and investigated using numerical simulation. It is obtained that high mixing intensity can be achieved by micromixer with inlet velocity of 0.6 m s⁻¹ and microfiltration meshes 10 μm in size. A micromixing-assisted platform consisted of two syringe pumps and a micromixer was manufactured to efficiently fabricate TiO₂ films via mixing of (NH₄)₂TiF₆ and CO(NH₂)₂ as reactants and fluorine doped tin oxide, F: SnO₂ (FTO), conducting glass substrates by LPD in alkaline solutions. The results suggest that surface morphology of TiO₂ films fabricated by micromixing can be easily controlled in comparison with that of specimens prepared by traditional stirring mixing process. The dense and well-ordered TiO₂ films derived from micromixing have enhanced adhesion strength, high hardness, good hydrophilic and excellent photoelectrochemical properties. Particularly, homogeneous reaction could be inhibited in micromixer and an ideal supersaturation solution would be formed via micromixing treatment, which significantly facilitates the formation of high quality TiO₂ films by heterogeneous nucleation on substrate surface. These obtained achievements are expected to promote further application of TiO₂ films in a variety of domains including photocatalysis and corrosion protection of metals.
Microemulsion-based synthesis of a visible-light-responsive Si-doped TiO<inf>2</inf> photocatalyst and its photodegradation efficiency potential
2018, Materials Chemistry and Physics
Citation Excerpt :
Different methods have been used to increase the photocatalytic efficiency of TiO2. These methods can be categorized as either morphological modifications, such as increased surface area and porosity, or as chemical modifications (application of other components in the TiO2 structure) [12,13]. However, visible light active TiO2 photocatalysts need chemical modifications.
In this research, a facile microemulsion route was applied in the synthesis of a series of Si-doped TiO₂ nanoparticles with uniform shape, narrow size distribution and high photocatalytic activity. The size and structure of the resulting crystals were evaluated by XRD and TEM techniques, respectively. The size of nanoparticles increased with the increment of water and calcination temperature. The photocatalytic activity of the nanoparticles was improved by decreasing the water amount in the system. In improving the crystallinity, the calcination led to the formation of quartz and anatase form of TiO₂. Moreover, it was shown that the highest catalytic activity strongly depends on both the molar ratio of water-to-AOT and calcination temperature. The temperature increase resulted in the increment of crystallinity, light adsorption, and particle size. The UV–visible diffused reflectance analysis proved that the doping of the silicon ions in the TiO₂ lattice can shift its optical absorption in the visible range. The size of the spherical nanoparticles was around 10–20 nm. Hence, Si-doped TiO₂ prepared by ME method yields excellent and uniform features resulting in better performance for future applications.
Improving mechanical and dielectric properties of polypropylene/poly (vinylidene fluoride) blends using polypropylene-graft-maleic anhydride and hybrid fillers
2022, Journal of Materials Science: Materials in Electronics

View all citing articles on Scopus

View full text

Conduction mechanism of metal-TiO2–Si structures

Highlights

Abstract

Introduction

Section snippets

Experimental methods

Results and discussion

Summary

Acknowledgment

Appl. Surf. Sci.

J. Non Cryst. Solids

Opt. Mater.

Opt. Mater.

Mater. Lett.

J. Appl. Phys.

Appl. Phys. Lett.

Semiconductors

J. Vac. Sci. Technol. A

Semiconductors

Conduction mechanism of metal-TiO₂–Si structures