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The present study reveals that ZrO2 MOS capacitor has been fabricated by RF sputtering technique. The maximum refractive index has been found to be 2.29 at 400 °C. From capacitance-voltage graph, it has been observed that the memory window and accumulation capacitance has been found to be maximum at 400 °C. The maximum memory window and accumulation capacitance has been found to be 0.50 V and 7.00 ×10−11 F, respectively. The flat band voltage shifts toward positive side at all temperatures. From current-voltage curve, it has been observed that the leakage current is found to be low at 400 °C and it is order of 10−7A at +20 V. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A metal–ferroelectric–insulator–semiconductor (MFIS) structure was fabricated with lanthanum (La)-doped BiFeO3 as ferroelectric and ZrO2 as the high-k insulator layer. The BiFeO3 film with 5 M doped La was prepared with sol–gel and ZrO2 film was physically deposited with rf sputtering. Films structural characteristics were obtained using X-ray diffraction and scanning electron microscopy (SEM). The ferroelectric film shows the perovskite structure with orientation (110)/(104) when annealed in the range from 400 to 700 °C. The dielectric film shows an amorphous structure for the same range of annealing temperature. Electrical and ferroelectric properties were obtained by fabricating and characterizing metal/ferroelectric/silicon (MFS), metal/ferroelectric/metal (MFM), metal/insulator/silicon (MIS), metal/ferroelectric/insulator/metal (MFIM) and metal/ferroelectric/insulator/silicon (MFIS) capacitor structures with ferroelectric film of 200 nm thickness and dielectric film of various thicknesses. MFS structure shows a maximum memory window of 3.5 V and leakage current density of 1.4 × 10–8 A/cm2 with ferroelectric film annealed at 500 °C. The memory window was further improved to 6.62 V and leakage current to the order 10–10 A/cm2 with the introduction of 9 nm insulator layer between ferroelectric and silicon. The same device shows an excellent endurance property tested for 1012 cycles and data retention tested for 5.56 h. The device shows a breakdown of 43 V, which is 9 V higher than the MFS structure. To the best of author's knowledge, this is the first report to integrate La-doped BiFeO3 on ZrO2 (high-k) dielectric for non-volatile memory applications. [ABSTRACT FROM AUTHOR]

BiFeO3 (BFO) and ZrO2 have been deposited on p-type (100) silicon substrate by sol-gel process and rf sputtering method, respectively. Metal-ferroelectric-insulator-semiconductor capacitor has been fabricated with 100 nm BFO and 10 nm ZrO2 shows maximum memory window of 1.54 V as compared to other fabricated capacitors with 5 and 15 nm insulating layer thickness. Improvement in current density has been also observed in different thickness of buffer layer of MFIS capacitors. The improved current density of order of 10-7 A/cm2 has been observed in MF(100nm)I(10nm)S structure. It has been also observed in MF(100nm)I(10nm)S structure that no charge value degrades up to 1011 iteration cycles. [ABSTRACT FROM AUTHOR]