Formation of Knbo3 Thin Films for Self-Powered Reram Devices and Artificial Synapses

ISBN-13: 9789811347887 / Angielski / Miękka / 2018 / 98 str.

Tae-Ho Lee

Spis treści

Abstract

Figure List

Table List

Chapter 1. Introduction

Chapter 2. Literature Survey

2-1. Lead-free Piezoelectric Ceramics

2-1-1. KN-based Thin Films

2-1-1-1. Necessity of KN-based Thin Films

2-1-1-2. Technological Requirement for KN-based Thin Films

2-1-2. Electrical properties of KN thin film

2-1-2-1. Capacitance Density

2-1-2-2. Dielectric Loss

2-1-2-3. Leakage Current Density

2-1-2-4. Leakage Current Mechanism

2-1-2-5. Piezoelectric Coefficient d₃₃

2-2. Memristor-based Neuromorphic System

2-2-1. Limits of Conventional Digital Computation

2-2-2. Neuromorphic Computing

2-2-2-1. Artificial Neural Networks

2-2-2-2. Basic Principle

2-2-2-3. Neuromorphic computation using VLSI (very-large-scale integration)

2-2-3. Human Brain

2-2-3-1. Neurons

2-2-3-2. Synapses

2-2-3-3. Synaptic Plasticity

2-2-3-4. Synaptic Metaplasticity

2-3. Memristor as Artificial Synapses

2-3-1. Memristor

2-3-1-1. Definition

2-3-1-2. Memristor types

2-3-1-3. ReRAM-based Memristor

2-3-2. Memristr Based Neural Networks

2-4. Piezoelectric Nanogenerators

2-4-1. Piezoelectric Energy Harvesting

2-4-2. Piezoelectric Nanogenerator

Chapter 3. Experimental Procedure

3-1. Preparation of KN Sputtering Target

3-1-1. Synthesis of KN Compound

3-1-2. Sintering of KN Ceramic Target

3-2. Experiments of KN Thin Films

3-2-1. Growth of KN Films

3-2-2. Analysis of structural and Electrical Properties of KN Thin Films

3-2-2-1. Crystal and Microstructure and Surface Morphology

3-2-2-2. Dielectric Properties

3-2-2-3. I-V Characteristics

3-2-2-4. P-E Hysteresis Curve and Piezoelectric Constant d33

3-3. KNbO₃ ReRAM Devices

3-3-1. Fabrication Pt/KN/TiN/SiO₂/Si Devices

3-3-2. Device measurements

3-3-2-1. Structural Characteristics

3-3-2-2. Electrical Characteristics

3-3-2-2-1. Spike-Timing Dependent Plasticity Characteristics (STDP)

3-4. KNbO₃ Piezoelectric Nanogenerators

3-4-1. Fabrication of KN Piezoelectric Nanogenerators

3-4-2. Device measurements

3-5. Biocompatibility Assessment of KN film

Chapter 4. Results and Discussion

4-1. Growth Behavior of KN Thin Films

4-1-1. X-ray Diffraction Patterns

4-1-2. SEM/EDX analysis and Auger depth profile

4-1-3. Electrical Properties of KN Thin Films

4-1-3-1. Dielectric Properties and I-V Characteristic of KN Thin Films

4-1-3-2. Polarization Characteristic and d₃₃ Values of KN Thin Films

4-2. KNbO₃-Based ReRAM Devices

4-2-1. KNbO₃/TiN/SiO₂/Si ReRAM Devices

4-2-1-1. Structural Properties of KN films

4-2-1-2. Structural and chemical analysis on the surface of the KN films

4-2-1-3. Nanocrystal of KN films

4-2-1-4. Resistive Switching and Reliability Characteristics of KN Films

4-2-1-5. Dielectric and Piezoelectric Properties

4-2-2. Current Conduction Mechanisms

4-2-2-1. Variations of the R_HRS and R_LRS with the Size of the ReRAM Device

4-2-2-2. Leakage current mechanism of the KN film in HRS grown at 350^oC

4-2-2-3. Conductive AFM (CAFM) analysis

4-2-2-4. X-ray photoelectron spectroscopy analysis

4-2-2-5. TEM analysis

4-3. KNbO₃-Based Piezoelectric Nanogenerators

4-3-1. Structural of KN/TiN/PI/PET PNG

4-3-2. KN Thin film PNGs

4-3-2-1. Piezoelectric Potential Developed in the KN PNGs

4-3-2-2. Electrical Output Energy of the KN PNG

4-3-2-2-1. Calculation and Measurement of Tensile Strain Developed in KN PNG

4-3-2-2-2. Output voltage, Current and Reliability Properties of the KN PNGs

4-3-2-2-3. Open-circuit voltages and short-circuit currents of KN PNG measured along the reverse direction.

4-3-2-2-4. Open-circuit voltages and short-circuit currents of KN PNG measured at strain and strain rate

4-3-2-2-5. Output powers at various load resistances and transferred charge

4-4. Self powered KNbO₃ ReRAM device

4-4-1. KN ReRAM operated by Piezoelectric KN PNG

4-4-2. KN ReRAM operated by Piezoelectric KN PNG with various strain and strain rate

4-5. KNbO₃-based Memristor

4-5-1. Switching Properties of KN Memristor

4-5-2. Electrical and Mechanical Reliability of the KN Memristor

4-5-3. Memristive Switching Mechanism of the KN Memristor

4-5-3-1. Temperature Dependence of Multi-level Resistance

4-5-3-2. Current Conduction Mechanism of KN memristor

4-5-4. Non-linear Transmission of the KN Memristor

4-5-5. Synaptic Plasticity of KN the Memristor

4-5-5-1. Short-term Plasticity and Long-term Plasticity

4-5-6. Spike-Rate-Dependent Plasticity of the KN Memristor

4-5-7. Spike-Timing-Dependent Plasticity of the KN Memristor

4-5-8. Metaplasticity of a KN Memristor

4-5-8-1. Metaplasticity on Long-term Potentiation

4-5-8-2. Metaplasticity on Long-term Depression

4-5-8-3. Synaptic Metaplasticity in the KN Memristor Stimulated by priming spike

4-6. Biocompatibility Assessment of KNbO₃ Thin films

Chapter 5. Conclusions

References

O autorze

Dr. Tae-Ho Lee received his Ph.D (2017) from department of Materials Science and Engineering, Korea University and is currently working in Korea Electronics Technology Institute.

Blurb

This thesis describes an investigation into homogeneous KN crystalline films grown on Pt/Ti/SiO2/Si substrates, amorphous KN films grown on TiN/Si substrates using the RF-sputtering method, and the ferroelectic and piezoelectric properties of these KN films. KNbO3 (KN) thin films have been extensively investigated for applications in nonlinear optical, electro-optical and piezoelectric devices.  However, the electrical properties of KN films have not yet been reported, because it is difficult to grow stoichiometric KN thin films due to K2O evaporation during growth.

This thesis also reports on the ReRAM properties of a biocompatible KN ReRAM memristor powered by the KN nanogenerator, and finally shows the biological synaptic properties of the KN memristor for application to the artificial synapse of a neuromorphic computing system.