Jun-Cheol Park1,Sanghan Lee1
Gwangju Institute of Science and Technology1
Jun-Cheol Park1,Sanghan Lee1
Gwangju Institute of Science and Technology1
Conventional perovskite such as BaTiO<sub>3</sub>, Pb(Zr, Ti)O<sub>3</sub>, and BiFeO<sub>3</sub> are promising materials for use in a next-generation memory device called Ferroelectric Random Access Memory (FeRAM). However, perovskite structures have a clear limitation of difficulty in applying with CMOS due to insufficient Si compatibility, and it is hard to exhibit ferroelectricity in extremely thin films. Recently discovered ferroelectric HfO<sub>2</sub> (hafnia), which has a fluorite structure, has tremendous potential in the memory industry owing to its Si compatibility in CMOS, eco-friendly (in terms of Pb free), and scaling-down. So far, numerous studies to reveal the origin of ferroelectricity in HfO<sub>2</sub> have been conducted. Due to these efforts, possible mechanisms related with “doping” and “oxygen vacancy” as one of the most likely causes of ferroelectric HfO2 had been suggested. Among them, doping is assumed to play the most significant role to exhibits ferroelectricity in HfO<sub>2</sub> thin films.<br/> Despite these considerable discoveries, there is still a lack of understanding about the basics of ferroelectricity in HfO<sub>2</sub>. To deeply understand fundamental properties of ferroelectric HfO2, single-crystal-like epitaxial thin films are necessary. However, it is very challenging to grow epitaxial thin films via conventionally used the ALD (Atomic Layer Deposition) process. PLD (Pulsed Laser Deposition) is well known advantageous process for the growth of epitaxial oxide thin films. Herein, we have epitaxially grew orthorhombic phase (111) preferred-oriented HfO2 with various dopants and concentrations via PLD to study the effect of dopants and doping concentrations on ferroelectricity. X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were performed to determine the crystallinity, crystal structure, and stoichiometry of grown doped-HfO<sub>2</sub> thin films. Furthermore, current-voltage (I-V) curves and polarization-electric field (P-E) loops were also measured for confirming the ferroelectricity of doped-HfO<sub>2</sub>.