Frequency dependence of performance in Ge negative capacitance PFETs achieving sub-30 mV/decade swing and 110 mV hysteresis at MHz

We report the first investigation of frequency dependence of performance in Ge HfZrO
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(HZO) negative capacitance (NC) pFETs. For Ge NC pFETs with internal gate [Fig. 1(b)], pulse measurement produces the significant increase in hysteresis compared to the DC measurement, but devices still remains sub-60 mV/decade subthreshold swing (SS). Ge NC pFETs without internal gate [Fig. 1(c)] show the little dependence of hysteresis, SS, and capacitance characteristics on pulse measurement (from DC to 1 μs). Ge NC pFET without internal gate achieves sub-30 mV/decade SS and 110 mV hysteresis with 1 ¡is pulse measurement, and significant peak in gate capacitance due to the NC effect at MHz. The different frequency dependences of performance in NC devices with and without internal gate might be attributed to the difference in the magnitude of gate leakage currents.