Structural and electrical properties of Al/BiFeO3/ZrO2/n-Si structure for non-volatile memory application

Abstract

In this communication, the structural and electrical properties of metal–ferroelectric–insulator–silicon (MFIS) capacitor structure have been reported for non-volatile memory applications. Sol–gel with spin coating and rf sputtering process have been used for depositing BiFeO3 (BFO) and ZrO2 films, respectively. It has been observed that BFO film shows pure ferroelectric phase, uniform grain size and maximum refractive index at annealing temperature of 500 °C. Thermo-gravimetric analyzer and differential scanning calorimetry analysis indicate good agreement with X-ray diffraction of BFO film. In ZrO2 thin film, it has been observed that ZrO2 is in amorphous state at all annealing temperatures and the maximum refractive index has been found at annealing temperature of 400 °C. Al/ZrO2/n-Si (MIS), Al/BiFeO3/n-Si (MFS) and Al/BiFeO3/ZrO2/n-Si (MFIS) structures have been fabricated to investigate the electrical characteristics. The memory window has been observed by capacitance–voltage (C–V) characteristics and it improves from 1.9 V in MFS structure to 5.4 V in MFIS structure with 8 nm dielectric layer. Leakage current density has been observed by current density–gate voltage (J–V) characteristics and it is order of 10−5 A/cm2 in MF150 nmI8 nmS structure. No charge value degrades up to 1012 iteration cycles in MF150 nmI8 nmS structure.