• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.570-576
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• 2007

In this study, the characteristics of metal-ferroelectric-semiconductor FET (MFSFET) device is investigated using field-dependent polarization and square-law FET models. From drain current with the gate voltage variation, when coercive voltages of ferroelectric thin film are 0.5 and 1V, the memory windows are 1 and 2V, respectively. When the gate voltages are 0, 0.1, 0.2 and 0.3V, the difference of saturation drain currents of the MFSFET device at two threshold voltages in ID-VD curve are 1.5, 2.7, 4.0, and 5.7mA, respectively. As a result of the analysis for drain currents after tine lapse, which is based on the simulation for hysteresis loop and the fitting of retention properties of ferroelectric thin films such as PLZT(10/30/70), PLT(10) and PZT(30/70) thin film shows excellent reliability that the decrease of saturation current is about 18% after 10 years.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.1
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• pp.1-10
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• 2003

Device characteristics of the Metal-Ferroclecric-Semiconductor FET(MFSFET) are simulated in this study. The field-dependent polarization model and the square-law FET model are employed in our simulation. C-V$_{G}$ curves generated from our MFSFET simulation exhibit the accumulation, the depletion and the inversion regions clearly. The capacitance, the subthreshold and the drain current characteristics as a function of gate bias exhibit the memory windows are 1 and 2 V, when the coercive voltages of ferroelectric are 0.5 and 1 V respectively. I$_{D}$-V$_{D}$ curves are composed of the triode and the saturation regions. The difference of saturation drain currents of the MFSFET device at the dual threshold voltages in I$_{D}$-V$_{D}$ curve is 1.5, 2.7, 4.0, and 5.7 ㎃, when the gate biases are 0, 0.1, 0.2 and 0.3V respectively. As the drain current is demonstrated after time delay, PLZT(10/30/70) thin film shows excellent reliability as well as the decrease of saturation current is about 18 % after 10 years. Our simulation model is expected to be very useful in the estimation of the behaviour of MFSFET devices.T devices.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.8
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• pp.894-900
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• 2006

The electrical characteristics associated with crystal structure changes as a function of La content for $(Pb_{1-x}La_x)(Zr_{0.5}Ti_{0.5})O_3$ thin films were investigated for applications in memory capacitors. Tetragonality of PLZT films decreased with increasing La content. Thin films with La $\geq$ 20 mol% were found to be cubic. Films with La $\geq$ 12 mol% exhibited broader dielectric peaks compared to those of bulk ceramics and behaved as relaxer ferroelectrics. Tetragonal PLZT film with 12 mol% La had a dielectric constant maximum of 1330 at room temperature and a charge storage density of ${\sim}18{\mu}C/cm^2$ at 5 V. Decrease in coercive field and remnant polarization with increase in La content were resulting from less dipolar response caused by the decreased crystal anisotropy. The leakage current densities $<10^{-8}A/cm^2$ up to 5 V bias voltage were observed for the films with La $\geq$ 14 mol%.