Composition and Electrode Effects on the Electrical Properties of SrBi2Ta2O9

AbstractSrBi2Ta2O9 has attracted great interest for non-volatile memory applications due to its minimal polarization fatigue. This paper describes systematic studies, using pulsed laser deposition, on the effect of deposition conditions on the Bi-Pt reaction and on the potential for low temperature processing. Changing the deposition temperature (Ts) and oxygen gas pressure during deposition can control the Bi content in the films. At a Ts of 600°C, the films have excess Bi and do not fully crystallize to SBT, resulting in poor remnant polarization (Pr). These films consist mostly of the pyrochlore phase, plus a small amount of disordered, c-oriented layered perovskite SBT. By annealing over 750°C, the films show improved Pr, but further Pt - Bi interactions occur. At a Ts of 700°C, the as-deposited films are fully crystallized and show saturated hysteresis loops. However, Bi deficiency through alloying results in reduced remnant polarization (2Pr = 7.0μC/cm2). Films on Ir/Pt show reduced electrode reactions and improved properties.

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Effect of Ta Nanobarrier in Magnetron Sputtering of Nd-Doped SrBi2Ta2O9 Thin Films

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.18293 ◽

2008 ◽

Vol 8 (5) ◽

pp. 2618-2622

Author(s):

Yibin Li ◽

Sam Zhang ◽

Thirumany Sritharan ◽

Xiaomin Li ◽

Yang Liu ◽

...

Keyword(s):

Thin Films ◽

Remnant Polarization ◽

Ferroelectric Properties ◽

Random Access ◽

Random Access Memory ◽

Layered Perovskite ◽

Interfacial Diffusion ◽

Access Memory ◽

Memory Applications ◽

Secondary Ion

SrBi2Ta2O9 (SBT) is a bismuth layered perovskite with attractive ferroelectric properties for random access memory applications. Our previous studies showed that Nd-doped SBT (SNBT) thin films exhibited an improved remnant polarization and reduced coercivity. This paper concentrates on the effect of Ta nanobarrier in between the SNBT and the Pt layers. Without the nanobarrier, severe bismuth diffusion is revealed by the secondary ion mass spectroscopy. However, with a nano layer (up to 2 nm) of Ta metal, the interfacial diffusion is effectively suppressed even at 800 °C. Details of the composition profiling, film crystallinity and remnant polarization are discussed in view of the nanobarrier thickness.

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Preparation and Characterization of Ba and Nb Substituted SrBi2Ta2O9 Compounds

MRS Proceedings ◽

10.1557/proc-655-cc5.6.1 ◽

2000 ◽

Vol 655 ◽

Cited By ~ 4

Author(s):

Rasmi R. Das ◽

P. S. Dobal ◽

A. Dixit ◽

W. Perez ◽

M.S. Tomar ◽

...

Keyword(s):

Raman Spectra ◽

Phase Formation ◽

Perovskite Phase ◽

Growth Conditions ◽

Layered Perovskite ◽

Phonon Modes ◽

Si Substrates ◽

Non Volatile Memory ◽

Lower Temperature ◽

Memory Applications

AbstractBi-layered ferroelectric compounds are considered most promising for non-volatile memory applications due to their high fatigue endurance. We have prepared SrBi2Ta2O9 powders with Ba (A sites) and Nb (B sites) substitutions using a novel solution based route. The powders were pressed and sintered at 1050°C to obtain high quality targets. Thin films were prepared using these ceramic targets on Pt/TiO2/SiO2/Si substrates using pulsed laser deposition (PLD) technique. The effects of growth conditions on phase formation as well as structural and electrical properties in films are studied. Initial results on films show good hysteretic characteristics. Though phase formation begins at much lower temperature, these films crystallize in a complete layered perovskite phase when prepared at 700°C. Optical phonon modes in these materials exhibit systematic variations with changing compositions. The changes in the Raman spectra are explained in terms of Ba and Nb substitutions at A and B sites, respectively. The temperature dependence of Raman spectra exhibits the substitution induced changes in the transition temperatures of these materials.

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Electrical properties of Pt/SrBi2Ta2O9/Bi4Ti3O12/p-Si heterostructure prepared by sol-gel processing

Journal of Materials Research ◽

10.1557/jmr.2006.0218 ◽

2006 ◽

Vol 21 (7) ◽

pp. 1782-1786 ◽

Cited By ~ 3

Author(s):

Hua Wang ◽

Min-Fang Ren

Keyword(s):

Current Density ◽

Annealing Temperature ◽

Sol Gel ◽

Pyrochlore Phase ◽

Hysteresis Loops ◽

Memory Window ◽

Low Temperature Processing ◽

Sweep Voltage ◽

Ferroelectric Hysteresis ◽

Gel Processing

Low-temperature processing as low as 550–700 °C of Pt/SrBi2Ta2O9 (SBT)/Bi4Ti3O12 (BIT)/p-Si heterostructure has been performed by a sol-gel method. The effects of annealing temperature on current density, C-V characteristics, and memory windows of Pt/SBT/BIT/p-Si heterostructure were investigated. The SBT/BIT multilayer films were polycrystalline with no pyrochlore phase and no preferred orientation. The leakage current density was under 3 × 10−7 A/cm2 at 5 V with asymmetry hysteresis loops for Pt/SBT/BIT/p-Si heterostructure. Although all C-V curves showed clockwise ferroelectric hysteresis loops and the memory window reached a maximum of 0.78 V at a sweep voltage of 5 V, the memory window changed asymmetrically with the variation of annealing temperature and sweep voltage. The maximum memory window of Pt/SBT/BIT/p-Si heterostructure prepared at lower temperatures was narrower at lower sweep voltage. The asymmetric behavior of the C-V characteristics was discussed in terms of electron injection from Si and the ferroelectric polarization effect.

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Microstructural Characterization of Ferroelectric Thin Films for Non-Volatile Memory Applications

MRS Proceedings ◽

10.1557/proc-200-231 ◽

1990 ◽

Vol 200 ◽

Cited By ~ 37

Author(s):

Sharon A. Myers ◽

Leo N. Chapin

Keyword(s):

Thin Films ◽

Lead Zirconate Titanate ◽

Pyrochlore Phase ◽

Microstructural Characterization ◽

Cmos Technology ◽

Lead Zirconate ◽

Ferroelectric Thin Films ◽

Grain Structure ◽

Non Volatile Memory ◽

Memory Applications

ABSTRACTFerroelectric thin films are now being used in conjunction with semiconductor CMOS technology to produce non-volatile IC memory devices. Three film compositions across the lead-zirconate-titanate (PZT) phase diagram were examined by transmission electron microscopy (TEM). The films are produced using organo-metallic sol-gels and sintered using standard semiconductor processing techniques. The grain structure of these thin films differ greatly from bulk ceramic crystals and thin films prepared using other deposition techniques. For two compositions, Pb1.1 (Zr0.75Ti0. 25)O3 and Pb1.1 (Zr0.50Ti0.50)O3, the perovskite structure was found in large rosettes surrounded by the polycrystalline pyrochlore phase. In the Pb1.1(Zr0.25Ti0.75)O3 sample, perovskite grains were found with no evidence of the pyrochlore phase. Ferroelectric domains were imaged in all three samples.

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Hysteresis Behavior of the Donor–Acceptor-Type Ambipolar Semiconductor for Non-Volatile Memory Applications

Micromachines ◽

10.3390/mi12030301 ◽

2021 ◽

Vol 12 (3) ◽

pp. 301

Author(s):

Young Jin Choi ◽

Jihyun Kim ◽

Min Je Kim ◽

Hwa Sook Ryu ◽

Han Young Woo ◽

...

Keyword(s):

Organic Semiconductor ◽

Field Effect ◽

Field Effect Transistor ◽

Memory Device ◽

Non Volatile Memory ◽

Device Applications ◽

Donor Acceptor ◽

Effect Transistor ◽

Volatile Memory ◽

Memory Applications

Donor–acceptor-type organic semiconductor molecules are of great interest for potential organic field-effect transistor applications with ambipolar characteristics and non-volatile memory applications. Here, we synthesized an organic semiconductor, PDPPT-TT, and directly utilized it in both field-effect transistor and non-volatile memory applications. As-synthesized PDPPT-TT was simply spin-coated on a substrate for the device fabrications. The PDPPT-TT based field-effect transistor showed ambipolar electrical transfer characteristics. Furthermore, a gold nanoparticle-embedded dielectric layer was used as a charge trapping layer for the non-volatile memory device applications. The non-volatile memory device showed clear memory window formation as applied gate voltage increases, and electrical stability was evaluated by performing retention and cycling tests. In summary, we demonstrate that a donor–acceptor-type organic semiconductor molecule shows great potential for ambipolar field-effect transistors and non-volatile memory device applications as an important class of materials.

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Dimensional transformation of chemical bonding during crystallization in a layered chalcogenide material

Scientific Reports ◽

10.1038/s41598-020-80301-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yuta Saito ◽

Shogo Hatayama ◽

Yi Shuang ◽

Paul Fons ◽

Alexander V. Kolobov ◽

...

Keyword(s):

Chemical Bonding ◽

Crystalline Phase ◽

Three Dimensional ◽

Atomic Layer ◽

Unusual Behavior ◽

Weakly Bound ◽

Covalently Bonded ◽

Non Volatile Memory ◽

Device Applications ◽

Memory Applications

AbstractTwo-dimensional (2D) van der Waals (vdW) materials possess a crystal structure in which a covalently-bonded few atomic-layer motif forms a single unit with individual motifs being weakly bound to each other by vdW forces. Cr2Ge2Te6 is known as a 2D vdW ferromagnetic insulator as well as a potential phase change material for non-volatile memory applications. Here, we provide evidence for a dimensional transformation in the chemical bonding from a randomly bonded three-dimensional (3D) disordered amorphous phase to a 2D bonded vdW crystalline phase. A counterintuitive metastable “quasi-layered” state during crystallization that exhibits both “long-range order and short-range disorder” with respect to atomic alignment clearly distinguishes the system from conventional materials. This unusual behavior is thought to originate from the 2D nature of the crystalline phase. These observations provide insight into the crystallization mechanism of layered materials in general, and consequently, will be useful for the realization of 2D vdW material-based functional nanoelectronic device applications.

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The electrical characteristics of metal-ferroelectric (PbZr/sub x/Ti/sub 1-x/O/sub 3/)-insulator(Ta/sub 2/O/sub 5/)-silicon structure for non-volatile memory applications

2000 International Semiconducting and Insulating Materials Conference. SIMC-XI (Cat. No.00CH37046) ◽

10.1109/sim.2000.939259 ◽

2002 ◽

Author(s):

Chi-Yuan Sze ◽

J.Y. Lee

Keyword(s):

Electrical Characteristics ◽

Silicon Structure ◽

Non Volatile Memory ◽

Volatile Memory ◽

Memory Applications

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Dependence of Ferroelectric Properties of SBT Based Capacitors on the Electrode Material

MRS Proceedings ◽

10.1557/proc-541-185 ◽

1998 ◽

Vol 541 ◽

Author(s):

S. Tirumala ◽

S. O. Ryu ◽

K. B. Lee ◽

R. Vedula ◽

S. B. Desu

Keyword(s):

Thin Films ◽

Electrode Material ◽

Electrode Materials ◽

Perovskite Phase ◽

Ferroelectric Properties ◽

Si Substrates ◽

Non Volatile Memory ◽

Metal Organic ◽

Sputter Deposited ◽

Memory Applications

AbstractThe effect of various electrode materials on the ferroelectric properties of SrBi2Ta2O9 (SBT) thin films has been investigated for non-volatile memory applications. Two sets of electrode structures, viz., Pt-Ir based and Pt-Rh based, were sputter deposited in-situ on Si substrates. SBT thin films were deposited on these electrodes using a metal-organic solution deposition technique followed by a post-deposition anneal at 750 °C in oxygen. Structural characterization revealed a polycrystalline nature with predominant perovskite phase in SBT thin films. Ferroelectric properties were studied in capacitor mode by depositing top electrodes, where the top electrode material is identical to that of the bottom electrode. Extensive analysis of the ferroelectric properties signify the important role played by the electrode material in establishing the device applicability is reported in this work.

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Resistive switching characteristics of all-solution-based Ag/TiO2/Mo-doped In2O3devices for non-volatile memory applications

Journal of Materials Chemistry C ◽

10.1039/c6tc03607d ◽

2016 ◽

Vol 4 (46) ◽

pp. 10967-10972 ◽

Cited By ~ 35

Author(s):

Sujaya Kumar Vishwanath ◽

Jihoon Kim

Keyword(s):

Resistive Switching ◽

Retention Time ◽

Elevated Temperatures ◽

Switching Behavior ◽

Memory Devices ◽

Bipolar Switching ◽

Non Volatile Memory ◽

Volatile Memory ◽

Switching Characteristics ◽

Memory Applications

The all-solution-based memory devices demonstrated excellent bipolar switching behavior with a high resistive switching ratio of 103, excellent endurance of more than 1000 cycles, stable retention time greater than 104s at elevated temperatures, and fast programming speed of 250 ns.

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