Nonideality of Negative Capacitance Ge Field-Effect Transistors Without Internal Metal Gate

We demonstrate negative capacitance (NC) Ge field-effect transistors (FETs) utilizing the TaN/HfZrO x /SiO 2 gate stack. Typical characteristics of NC transistors, including the sub-60 mV/decade subthreshold swing (SS), the gate capacitance {C} _{G} peak, and the negative differential resistance e...

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Veröffentlicht in:IEEE electron device letters 2018-04, Vol.39 (4), p.614-617
Hauptverfasser: Wu, Jibao, Kanyang, Ruoying, Han, Genquan, Zhou, Jiuren, Liu, Yan, Wang, Yibo, Peng, Yue, Zhang, Jincheng, Sun, Qing-Qing, Zhang, David Wei, Hao, Yue
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Sprache:eng
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Zusammenfassung:We demonstrate negative capacitance (NC) Ge field-effect transistors (FETs) utilizing the TaN/HfZrO x /SiO 2 gate stack. Typical characteristics of NC transistors, including the sub-60 mV/decade subthreshold swing (SS), the gate capacitance {C} _{G} peak, and the negative differential resistance effect are achieved in NC Ge FETs without internal metal gate. Significant {C} _{\textit {G}} peak, as the evidence of NC effect is obtained in NC transistors at the frequency up to MHz. Ferroelectric Ge FETs with counterclockwise {I} _{\text {DS}} - {V} _{\text {GS}} loops due to trapping/detrapping, opposite hysteresis to the NC switching are also observed. The NC transistor has much steeper SS compared to the device dominated by the trapping/detrapping process. Statistical results show that only 10% of devices are dominated by the NC effect, and the density of defects in ferroelectric needs to be reduced to improve the yield of NC transistors.
ISSN:0741-3106
1558-0563
DOI:10.1109/LED.2018.2810203