Effect of Forming Gas High-Pressure Annealing on Metal-Ferroelectric-Semiconductor Hafnia Ferroelectric Tunnel Junction

Abstract

The various structures of ferroelectric tunnel junctions (FTJs) are widely studied. Among them, metal-ferroelectric-semiconductor (MFS) FTJs show great tunneling electroresistance (TER) ratio by forming a depletion region. However, the poor ferroelectricity of hafnia on semiconductor electrodes degrades the TER ratio. This study employed high-pressure annealing with forming gas to improve the ferroelectric properties of MFS FTJs. We achieved a high 2Pr value (47.54 μc/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) and large TER ratio (22) in MFS FTJ for a 6 nm thick hafnia layer annealed at high pressure (200 atm) with forming gas. This work helps improve the quality of interface between a semiconductor and ferroelectric layer to increase the ferroelectricity of MFS stack devices.