Sol–gel derived BST (BaxSr1−xTiO3) thin film ferroelectrics for non-volatile memory application with metal–ferroelectric–semiconductor (MFS) structure

Thin film of Barium–Strontium–Titanate (BaxSr1−xTiO3) has been fabricated through sol–gel spin-coating process with optimized value of ‘x’ for non-volatile memory application. The Metal–Ferroelectric–Semiconductor (MFS) thin-film structures have been prepared using Barium–Strontium–Titanate (BST) with various Barium/Strontium (Ba/Sr) molar concentrations. The BST films prepared through sol–gel process are annealed at 650 °C in nitrogen ambient. The structural and electrical characterizations have been carried out for each of the samples. From the characterization, it is realized that the BST films are having significant changes in its electrical and structural properties on changing the molar concentration of Barium and Strontium. It has been observed that the crystallinity of the film, refractive index, leakage current (I−V), capacitance vs. voltage (C−V) relation, and the charge vs. voltage (Q–V) relation vary with the varying values of ‘x’ in BaxSr1−xTiO3 and have been presented graphically. The maximum memory window up to 9 V with average leakage current within the range of 100 nA and minimum of 10 pA for 0 V has been achieved for the sweep voltage of + 15 V to -15 V. Memory window and leakage current are optimized and discussed. Endurance testing through PUND (positive up negative down) pulse shows that the samples can sustain up to 1010 iteration pulses. These findings indicate the use of optimized BST film for ferroelectric non-volatile memory applications through sol–gel process.