Browsing by Author "Wang, Shih-An"

Now showing 1 - 4 of 4

High performance negative capacitance field-effect transistor featuring low off-state current, high on/off current ratio, and steep sub-60 mV dec(-1) swing
(2020-04-01)
Liu, Chien
;
Chen, Hsuan-Han
;
Tung, Yi-Chun
;
Wang, Wei-Chun
;
Huang, Zhong-Ying
In this work, we demonstrated that the 5-nm-thick HfAlOx negative capacitance transistor (NCFET) with optimized Al doping can achieve a minimum 33 mV dec(-1) subthreshold swing (SS), an ultralow l(off) of 7.44 fA mu m(-1), and a high l(on)//l(off) ratio of 1.9 x 10(8). The NC switching with sub-60 mV dec(-1) SS can be implemented from V-DS - 0.2 V to 0.8 V due to an ultralow off-state leakage current. The experimental results reveal that well-controlled Al doping in HfAlOx not only reduces off-state leakage of the transistor, but also improves the ferroelectric NC effect to achieve a sub-60 mV dec-1 switching under a favorably low sub-1 voltage. This scaled HfAlOx NCFET with optimized Al doping and fluorine defect passivation shows the great potential for the application of low power logic devices. (C) 2020 The Japan Society of Applied Physics
Improved Negative-Capacitance Switch of Ferroelectric Field Effect Transistor Using Defect Passivation Engineering
(2019-02-01)
Cheng, Chun-Hu
;
Fan, Chia-Chi
;
Hsu, Hsiao-Hsuan
;
Wang, Shih-An
;
Chang, Chun-Yen
A ferroelectric negative-capacitance (NC) transistor using aluminum-doped hafnium oxide (HfAlOx) with fluorine passivation is successfully demonstrated. The fluorine-passivated device shows a nearly hysteresis-free forward/reverse swing of sub-30 mV dec(-1) for symmetric switch, a wide sub-60 mV (dec center dot swing)(-1) range over 4 decades of drain current, an ultralow off-leakage current of 4 fA mu m(-1), and a high on/off current ratio of >10(8). The fluorine defect passivation (FP) reduces oxygen vacancies of ferroelectric HfAlOx to mitigate interface depolarization field and thereby reinforce surface potential amplification effect during NC operation.
Investigation of Gate-Stress Engineering in Negative Capacitance FETs Using Ferroelectric Hafnium Aluminum Oxides
(2019-02-01)
Cheng, Chun-Hu
;
Fan, Chia-Chi
;
Liu, Chien
;
Hsu, Hsiao-Hsuan
;
Chen, Hsuan-Han
In this paper, we reported a ferroelectric HfAlOx negative capacitor transistor with gate-stress (GS) engineering. Compared to control device, the HfAlOx transistor with GS engineering percentage of I-ON enhancement and 27% V-T reduction under the assistance of the negative capacitance (NC) effect. The orthorhombic phase transition played a crucial role in realizing the NC effect. From the results of the material analysis, the theoretical Landau simulation and electrical measurement, we demonstrated that the GS is favorable for inducing orthorhombic phase crystallization of HfAlOx and stabilizing the NC effect, which shows the potential for the application of advanced technology node.
Investigation on polarization characteristics of ferroelectric memories with thermally stable hafnium aluminum oxides
(2019-08-01)
Chang, Tun-Jen
;
Liu, Chien
;
Fan, Chia-Chi
;
Hsu, Hsiao-Hsuan
;
Chen, Hsuan-Han
In this work, we successfully demonstrated the 9.6-nm-thick HfAlOx ferroelectric memory using light aluminium doping of 6.5% to form ferroelectric orthorhombic phase. Compared to ferroelectric HfZrOx film with zirconium diffusion issue, the HfAlOx film showed excellent thermal stability under high temperature annealing. Besides, the ferroelectric HfAlOx also exhibited robust polarization characteristics under endurance cycling test. A > 10(6) stressed cycles with 4 MV/cm can be measured and a long endurance was sustained over 5 x 10(7) cycles under 3.6 MV/cm. Therefore, the HfAlOx film showed the great promise for integrating in high performance ferroelectric memory with thermal budget concerns.