Properties of Ultrathin High Permittivity (Nb[sub 1−x]Ta[sub x])[sub 2]O[sub 5] Films Prepared by Aqueous Chemical Solution Deposition

Abstract

Ultrathin (normalNb1−xnormalTax)2normalO5 films, with thicknesses from ∼3to∼25nm , were deposited by chemical solution deposition starting from aqueous precursor solutions. The film’s dielectric properties were characterized by capacitance–voltage and current–voltage measurements. Permittivities ranged from 20 to 31 after annealing at 600°C , with the highest value obtained for pure normalNb2normalO5 . With increasing Nb content, increasing leakage currents were observed. The crystallization temperature was determined by in situ X-ray diffraction measurement for films with ∼15nm thickness: normalNb2normalO5 was crystalline as deposited (600°C) , while the crystallization temperature of solid solutions increased with increasing Ta content, up to 875°C for pure normalTa2normalO5 . NbTanormalO5 showed a marked increase in permittivity from 27 to 38 after crystallization anneal at 600 and 800°C , respectively. For normalNb2normalO5 , no significant difference in permittivity was observed between amorphous and crystalline layers.

Controlled Polarizability of One‐Nanometer‐Thick Oxide Nanosheets for Tailored, High‐κ Nanodielectrics

“…In Figure a, we summarize the maximum ϵ r values for the titano niobate nanosheets, as well as those of various high‐ κ thin films for comparison. In the ultrathin region (<20 nm), the κ values of the titano niobate nanosheets are larger than those of the other high‐ κ materials 7, 20, 26–30. The high ϵ r values of the titano niobate nanosheets persist even in the <10 nm region, which is in sharp contrast to the size‐induced dielectric collapse in typical high‐ κ materials such as (Ba (1‐ x ) Sr x )TiO 3 .…”

Aqueous citrato-oxovanadate(iv) precursor solutions for VO2: synthesis, spectroscopic investigation and thermal analysis

“…18,27 Therefore citrate is added to the solution as an α-hydroxy-carboxylato, cross-linking complexing agent. [34][35][36] Two different solutions are studied: (i) an aqueous citrato-oxalato-VO 2+ precursor, in which the oxalate groups remain in the solution and (ii) a citrato-VO 2+ solution whereby the oxalate groups are removed from the solution. In both solutions, the VO 2+ and citrate concentration equals 0.1 M and 0.2 M, respectively.…”

Gadolinium -niobates and -tantalates: Amorphous High-k Materials by Aqueous CSD

“…[11][12][13] In this work, a lanthanum oxide viz. Gd 2 O 3 , with a high bandgap (5.9eV) 14 but a moderate k value (k∼16 15,16 ), is used in combination with Nb 2 O 5 and Ta 2 O 5 , with a smaller bandgap (Nb 2 O 5 : 3.4 eV, Ta 2 O 5 : 3.9-4.5 eV) 17 but a high k value (Nb 2 O 5 : k∼35-50, Ta 2 O 5 : k∼25-44 15,[17][18][19][20][21] ), to form ultrathin amorphous oxide layers. A combination of Gd with Nb/Ta is chosen to investigate the effect on crystallization, leakage current, k-value and bandgap properties.…”