Electronic Conductivity and Dielectric Properties of Nanocrystalline CeO2 Films

Abstract

The growth of dielectric layers on silicon substrates has attracted a great deal of recent interest given their potential applicability in the fabrication of high quality silicon-on-insulator (SOI) structures, high density capacitor devices, and stable buffer layers between silicon and other materials. In this study, nanocrystalline CeO 2 films were deposited on n-type (100) silicon substrates using pulsed laser deposition (PLD) to form a gate dielectric for a Pt/n-Si/CeO 2 /Pt MOS device. XRD, AFM and FESEM measurements were used to characterize the crystal structure and grain size of the CeO 2 films. The electrical properties of the device structure were examined by capacitance-voltage (C-V) and impedance spectroscopy measurements. The CeO 2 films exhibited an activated conductivity, characterized by an activation energy E a = 0.45 eV. An estimated room temperature electron mobility µ e of 2.8 × 10 −7 cm 2 /Vs leads to a corresponding electron concentration n of 5.5 × 10 17 cm −3 . In contrast to conventional MOS capacitors, we find an additional capacitive contribution under strong accumulation conditions as a result of space charge effects inside the CeO 2 thin film.

Nanostructured ceria-based materials: synthesis, properties, and applications

“…Some of the physical properties of CeO 2 are listed in Table 1. [32][33][34][35][36] Like stabilized zirconia, cerium oxide can accommodate a high oxygen deficiency by the substitution of lower valent elements on the cation sublattice. This leads to high oxygen ion conductivities and its interest as a solid electrolyte in solid oxide fuel cells.…”

“…165 Â 10 9 N m À2 Poisson's ratio 32 ca. 0.3 Hardness 32 5-6 Electronic conductivity (25 C) 33 2.48 Â 10 À8 S cm À1 Ionic conductivity (1000 C, in air) 34,35 3.13 Â 10 À3 S cm À1 (600 C, in air) 34 4.08 Â 10 À5 S cm À1 (600 C, in H 2 ) 34 1.11 Â 10 À3 S cm À1 Formation energy (25 C, 1 atm) 36 À1025.379 kJ mol À1 Magnetic susceptibility (c mol ) 36 26 Â 10 À6 cm 3 mol À1 Space charge models are widely used to describe the electrochemical behavior of surfaces and interfaces in ionic solids 57,58 which are based on the fact that defect formation energies at surfaces differ from those in the bulk. This leads to an electric gradient near the surface, to maintain a thermodynamic equilibrium.…”

Semiconductor Heterostructure SrTiO3/CeO2 Electrolyte Membrane Fuel Cells

“…When the Ce 4+ was reduced to Ce 3+ on fuel cell operation, the electronic fast channels are formed in the bulk CeO 2 , resulting in the OCV loss. 15,29 Therefore, the maximum power density of fuel cell based on CeO 2 is only 493.8 mW cm −2 at 550°C. However, the OCV increased to 1.1 V in the fuel cell based on STO/CeO 2 (1:9) composite, and the maximum power density was 745.6 mW cm −2 at 550°C, which is higher than pure STO (609.4 mW cm −2 ).…”

Enhanced Erbium-Doped Ceria Nanostructure Coating to Improve Solar Cell Performance

“…A simulation model has been built in a two-dimensional (2D), semiconductor module. This model deals with REDC NPs as it is a conductive layer with a band gap $E_g=3.31$eV, room temperature conductivity $\text{σ}=77\times {10}^{-6}\text{ S}/\text{cm}$, and electron mobility ${\text{μ}}_{\text{e}}=2.8\times {10}^{-7}{\text{ cm}}^2/\text{V}·\text{s}$ [20,21]. From Figure 6, it has been proved that a REDC NP coated cell has a little bit of improvement in the generation rate curve.…”