Approach for enhanced polarization of polycrystalline bismuth titanate films by Nd3+/V5+ cosubstitution

Abstract

Thin films of Nd 3ϩ -substituted bismuth titanate, (Bi 4.00Ϫy ,Nd y )Ti 3.00 O 12 ͑BNT͒, Nd 3ϩ /V 5ϩ -cosubstituted bismuth titanate, (Bi 4.00Ϫy ,Nd y )(Ti 3.00Ϫx V x )O 12 ͑BNTV͒, and La 3ϩ -substituted bismuth titanate, (Bi 3.25 ,La 0.75 )Ti 3.00 O 12 ͑BLT͒ were fabricated on the (111)Pt/Ti/SiO 2 /(100)Si substrates by a chemical solution deposition technique. These films possessed random-oriented polycrystalline structure. The BNT film had larger remnant polarization ( P r ) than the BLT film; P r and coercive field (E c ) of the BNT film with yϭ0.50 were 32 C/cm 2 and 126 kV/cm, respectively. Furthermore, V 5ϩ substitution improved the P r value of the BNT film up to 37 C/cm 2 ͑BNTV film; yϭ0.50, xϭ0.02), while the BNTV film had an E c value of approximately 119 kV/cm which was similar to that of the BNT film. Ferroelectric properties of the Pb-free polycrystalline BNT and BNTV films are comparable with those of conventional Pb-based ferroelectric films like a lead zirconate titanate.

Ferroelectric properties of (Bi3.15 Nd 0.85 )Ti 3 O 12 with decreasing film thickness

“…In comparison to the widely used Pb(Zr,Ti)O 3 (PZT) and SrBi 2 Ta 2 O 9 (SBT) for FRAM, Nd-doped Bi 4 Ti 3 O 12 exhibits a combination of high fatigue resistance, retention of nonvolatile polarization, together with a relatively lower processing temperature [2][3][4][5]. Several deposition techniques, including solgel [4][5][6], pulsed laser deposition (PLD) [7,8], metalorganic chemical vapor deposition (MOCVD) [9], and RF sputtering, have been employed to synthesize Nd 2 O 3 -doped Bi 4 Ti 3 O 12 (NBdT) based thin films [10].…”

Integration and High-Temperature Characterization of Ferroelectric Vanadium-Doped Bismuth Titanate Thin Films on Silicon Carbide

“…Other scalable production methods include chemical solution deposition (CSD) methods, such as sol-gel. 2,3 The experimental results are primarily compared with the results of Choi et al, 2 who used the same metal-ferroelectric-metal (MFM) device structure on silicon, with the difference of using CSD. MFM capacitors are expected to show better stability over a wide range of temperature as compared with metal-ferroelectric-semiconductor (MFS) capacitors.…”

“…21 Ferroelectric processing takes place after the HT front-end-of-line (FEOL) but before the low-temperature back-end-of-line (BEOL). A commonly cited 3,7,10 advantage of BiT compared with SBT is the low processing temperature, which is in the range from 650°C to 750°C. 2,3,7,10,11 However, this processing temperature could still be too high for modern silicon very-large scale integration (VLSI, more than 10 9 transistors on a chip), for which the thermal budget may be lower than 600°C after nickel salicidation.…”

“…B-site substitution can effectively reduce leakage current and improve ferroelectric properties, and experimental work has been done on Nb, 2,3 V, [2][3][4][5][6][7] W, 2 and Mo. 8 In a comparison between different Bsite dopants, V-doped BiT (BiTV) was shown to have lower leakage currents than BiT doped with W or Nb.…”

Study on Substitution Effect of Bi4Ti3O12 Ferroelectric Thin Films

“…For applications in NvFRAM devices, ferroelectric materials should have high remanent polarization, low coercive field (E c ), low fatigue rate and low leakage current density. However, BIT thin film has much lower values of switching polarization and suffers from poor fatigue endurance and high leakage current as a result of the internal defects (Uchida et al, 2002). Numerous works have been made to substitute BIT thin film with proper ions to optimize the ferroelectric properties.…”