Enhanced Non-Linearity Factor in Ferroelectric Tunnel Junction Based on HfO2 Heterojunction

Abstract

Ferroelectric polarization, related to charge conduction, has shown some intriguing properties in ferroelectric tunnel junction as it has higher on/off ratio, lower power consumption and shorter process time. Conventional ferroelectrics have various problems when it is based on perovskite structure material, such as poor Si-compatibility, lead pollution and small energy bandgap. Recently, both ferroelectricity and anti-ferroelectricity have been reported in doped HfO2 thin film (<30 nm). The ferroelectricity and anti-ferroelectricity HfO2 thin films can be extremely thin with good Si-compatibility and large bandgap (>5 eV). Anti-ferroelectric/ferroelectric HfO2 heterojunction can enhance fatigue property and non-linearity of single ferroelectric tunnel junction. The space charge can be induced due to the stress in ferroelectric layer or ferroelectric/metal interface in 90° domain switching while anti-ferroelectric lowers the stress in the 180° domain switching. The HfO2 heterojunction can have non-linearity as it has higher resistance state under the threshold voltage for polarization switching. This structure with good fatigue property and non-linearity factor would contribute to the enhancement of ferroelectric tunnel junction memory device. This research was supported by the MOTIE (Ministry of Trade, Industry & Energy (#10080643) and KSRC (Korea Semiconductor Research Consortium) support program for the development of the future semiconductor device.