X-ray diffraction patterns of films after crystallization annealing. The is polycrystalline with the phases of and prominently displayed.
Setup of the pulsed measurement.
(a) curves of capacitor with gate. The curve shifts to right after negative bias due to polarization. The inset shows the leakage current of the gate stack between and . The leakage is less than in this range; (b) curves of the same capacitor. The curve shifts to left after negative bias.
with different pulse edge slopes. The hysteresis magnitude decreases with the reduction of pulse edge slope, and is nearly on a straight line in a log-linear scale. (a) curves at different pulse edge slopes; (b) at as a function of pulse edge slope.
Diagram of electron trapping and detrapping during . The gate voltage is swept from accumulation (a) to inversion (c) and then swept back to accumulation (f). In the gate stack, there were less negative charge at flat-band condition (e) than flat-band condition (b) due to the slow response of electron trapping detrapping.
Pulsed curves under different pulse width while the pulse edge is kept as . There is nearly no difference in the hysteresis magnitude while the pulse width increases from to . As a result, the electron detrapping process is fast under negative bias.
and pulse of capacitors with and gate. Both and show same hysteresis direction on the stack. There is no hysteresis in or on stack. (a) ; (b) .
Calculated in and the normalized difference between and in stack. The is set at two values, and , respectively. Increase the remnant polarization with the decrease of trap density is the ideal method to reduce the effect of electron trapping-detrapping delay.
at is plotted as a function of scan range in the capacitors with and stacks. The first increase with scan range due to the electric field increase in the layer. After reaches the maximum value, it starts to decrease due to the hole injection under high field.
The normalized at (memory windows) and the shift of center [the change of at ] as a function of stress pulse number. The memory window decreases fast. The center shifts to positive direction due to the electron trapping during stress.
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