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Low-Frequency Noise Characteristics in SONOS Flash Memory With Vertically Stacked Nanowire FETs
Bang, Tewook,Lee, Byung-Hyun,Kim, Choong-Ki,Ahn, Dae-Chul,Jeon, Seung-Bae,Kang, Min-Ho,Oh, Jae-Sub,Choi, Yang-Kyu IEEE 2017 IEEE electron device letters Vol.38 No.1
<P>Low-frequency (LF) noise in a vertically stacked nanowire (VS-NW) memory device, which is based on the silicon-oxide-nitride-oxide-silicon(SONOS) configuration is characterized in two different operational modes, an inversion-mode and a junctionless-mode (JM). The LF noise showed 1/f-shape behavior regardless of the operational mode and followed the carrier number fluctuation model. With regard to the device-to-device variation and quality degradation of the LF noise after iterative program/erase operations, the five-story JM SONOS memory showed comparatively high immunity arising from its inherent bulk conduction and no-junction feature. Despite the harsh fabrication condition used to construct five-story VS-NW, even the five-story JM SONOS memory exhibited LF noise characteristics comparable to those of one-story JM SONOS memory. Thus, the five-story JM SONOS memory is attractive due to its high-performance capabilities and good scalability.</P>
Bae, Hagyoul,Bang, Tewook,Kim, Choong-Ki,Hur, Jae,Kim, Seyeob,Jeon, Chang-Hoon,Park, Jun-Young,Ahn, Dae-Chul,Kim, Gun-Hee,Son, Yunik American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.5
<P>We report an accurate extraction technique of effective mobility (mu(eff)) by considering gate-bias (V-GS) dependent effective inversion charges (Q(inv,eff)) as a normalized correction factor (sigma(V-GS)) when using the gate-to-source/drain capacitance-voltage (C-V) measurement in a p-channel Si/SiGe MOSFET with a floating body structure. In the proposed technique, two different capacitance-voltage configurations: a gate-to-source/drain (CG-SD) configuration without body contact and a gate-to-source/drain/body (CG-SDB) configuration with body contact are utilized for the accurate extraction of mu(eff).</P>
Lee, Seung-Wook,Bang, Tewook,Kim, Choong-Ki,Hwang, Kyu-Man,Jang, Byung Chul,Moon, Dong-Il,Bae, Hagyoul,Seo, Myungsoo,Kim, Seong-Yeon,Kim, Do-Hyun,Choi, Sung-Yool,Choi, Yang-Kyu IEEE 2017 IEEE electron device letters Vol.38 No.8
<P>The low-frequency noise (LFN) characteristics of a vertical pillar-type FET were investigated in order to observe the different influences of the source resistance (R-S) and the drain resistance (R-D). Because of its inherent vertical channel structure, the R-S and R-D are inevitablydifferent. To observe the effects of the asymmetric RS and RD on LFN, a forward mode (F-M) and reverse mode (RM) of voltage sweep were used. In the RM, the correlatedmobility fluctuation effect was higher and the power spectral density of resistance fluctuation (S-RSD) was lower than those in the FM. In addition, S-RSD was correlated with the R-S, but little with the R-D. To suppress S-RSD, it is important to minimize the R-S.</P>
Ui-Sik Jeong,Choong-Ki Kim,Hagyoul Bae,Dong-Il Moon,Tewook Bang,Ji-Min Choi,Jae Hur,Yang-Kyu Choi Institute of Electrical and Electronics Engineers 2016 IEEE transactions on electron devices Vol.63 No.5
<P>Low-frequency noise (LFN) behaviors, characterized with an SONOS-based gate-all-around junctionless nanowire (JLNW), are investigated to determine the suitability of this type of NW as a memory cell structure. LFN exhibits a 1/f-shape and is described by a carrier number fluctuation noise model. It is found that the proposed device structure shows a low level of device-to-device variation and high immunity against Fowler-Nordheim tunneling stress. Due to the centered conduction path in the JLNW device, the impact of correlated mobility fluctuations on the LFN is insignificant. The trapped charge in the nitride layer of the Silicon(Poly-Si)-oxide(SiO2)-nitride(SiNx)oxide(SiO2)-silicon(Single-crystalline) (SONOS) device also negligibly influences the LFN. The NW width-dependence is clarified in terms of the effects of the oxide trap density and source/drain series resistance under a fresh and a programmed state.</P>
A Vertically Integrated Junctionless Nanowire Transistor
Lee, Byung-Hyun,Hur, Jae,Kang, Min-Ho,Bang, Tewook,Ahn, Dae-Chul,Lee, Dongil,Kim, Kwang-Hee,Choi, Yang-Kyu American Chemical Society 2016 NANO LETTERS Vol.16 No.3
<P>A vertically integrated junctionless field-effect transistor (VJ-FET), which is composed of vertically stacked multiple silicon nanowires (SiNWs) with a gate-all-around (GAA) structure, is demonstrated on a bulk silicon wafer for the first time. The proposed VJ-FET mitigates the issues of variability and fabrication complexity that are encountered in the vertically integrated multi-NW FET (VM-FET) based on an identical structure in which the VM-FET, as recently reported, harnesses a source and drain (S/D) junction for its operation and is thus based on the inversion mode. Variability is alleviated by bulk conduction in a junctionless FET (JL-FET), where current flows through the core of the SiNW, whereas it is not mitigated by surface conduction in an inversion mode FET (IM-FET), where current flows via the surface of the SiNW. The fabrication complexity is reduced by the inherent JL structure of the JL-FET because S/D formation is not required. In contrast, it is very difficult to dope the S/D when it is positioned at each floor of a tall SiNW with greater uniformity and with less damage to the crystalline structure of the SiNW in a VM-FET. Moreover, when the proposed VJ-FET is used as nonvolatile flash memory, the endurance and retention characteristics are improved due to the above-mentioned bulk conduction.</P>
Lee, Geon-Beom,Kim, Choong-Ki,Park, Jun-Young,Bang, Tewook,Bae, Hagyoul,Kim, Seong-Yeon,Ryu, Seung-Wan,Choi, Yang-Kyu IEEE 2017 IEEE electron device letters Vol.38 No.8
<P>The hot-carrier-induced damage of a gate dielectric was cured with Joule heat generated by the forward current of the p-n junction between the body and drain, for the first time. The effective recovery voltage and pulse timewere optimized to cure the gatedielectricdamage produced by hot-carrier injection. Moreover, iterative damage and cyclic curing were experimentally demonstrated. Throughlow-frequency noise analyses, the degradationand recovery were verified by identifying trap density along the depth of the gate dielectric. Furthermore, this proposed method produced nearly the same recovery characteristics through source-to-body junction current in a short-channel device.</P>
Vertically Integrated Multiple Nanowire Field Effect Transistor
Lee, Byung-Hyun,Kang, Min-Ho,Ahn, Dae-Chul,Park, Jun-Young,Bang, Tewook,Jeon, Seung-Bae,Hur, Jae,Lee, Dongil,Choi, Yang-Kyu American Chemical Society 2015 NANO LETTERS Vol.15 No.12
<P>A vertically integrated multiple channel-based field-effect transistor (FET) with the highest number of nanowires reported ever is demonstrated on a bulk silicon substrate without use of wet etching. The driving current is increased by 5-fold due to the inherent vertically stacked five-level nanowires, thus showing good feasibility of three-dimensional integration-based high performance transistor. The developed fabrication process, which is simple and reproducible, is used to create multiple stiction-free and uniformly sized nanowires with the aid of the one-route all-dry etching process (ORADEP). Furthermore, the proposed FET is revamped to create nonvolatile memory with the adoption of a charge trapping layer for enhanced practicality. Thus, this research suggests an ultimate design for the end-of-the-roadmap devices to overcome the limits of scaling.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2015/nalefd.2015.15.issue-12/acs.nanolett.5b03460/production/images/medium/nl-2015-034602_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl5b03460'>ACS Electronic Supporting Info</A></P>
Silicon-Based Yagi-Uda Antenna Reflector
Jae Hur,Choong-Ki Kim,Da-Jin Kim,Tewook Bang,Yang-Kyu Choi,Young-Kyun Cho,Cheol Ho Kim,Bonghyuk Park,Jang-Soon Park,Dongho Kim 대한전자공학회 2017 대한전자공학회 학술대회 Vol.2017 No.1
A silicon-based “plasma antenna” has attracted substantial attentions due to the semiconductor’s natural ability to reconfigure itself from a metal state to an insulator state, and vice versa. The silicon enables the plasma antenna to operate as a highly practicable and low-cost reconfigurable antenna because the external electromagnetic field is coupled with an electron-crowded plasma channel. Given these characteristics, it was found that the silicon-based plasma channel is capable of becoming a reconfigurable reflector which redirects electromagnetic energy by reflecting an incoming signal back toward its original direction. In this work, the performance of a silicon-based reflector mounted on a Yagi-Uda antenna is presented. A numerical simulation is carried out to demonstrate the feasibility of the antenna as a plasma channel, prior to its fabrication. The I-V characteristics of the fabricated device are consequently shown, and finally the maximum gain along with its beam pattern is demonstrated.
Jae Hur,Byung-Hyun Lee,Min-Ho Kang,Dae-Chul Ahn,Tewook Bang,Seung-Bae Jeon,Yang-Kyu Choi IEEE 2016 IEEE electron device letters Vol.37 No.5
<P>A comprehensive analysis of the gate-induced drain leakage (GIDL) current of vertically stacked nanowire (VS-NW) FETs was carried out. In particular, two different operational modes of the VS-NW, an inversion mode (IM) and a junctionless mode (JM), were compared. The GIDL current of the JM-FET was considerably smaller than that of the IM-FET, and the reason for the difference was consequently determined by numerical simulations. It was found that the source of the difference between the IM-FET and JM-FET was the difference in source/drain (S/D) doping concentration, where the depletion width becomes the tunneling width, considering a long extension length at the S/D regions. The experimental results showed that the GIDL current of the NW FET was significantly controlled by longitudinal band-to-band tunneling (BTBT), rather than the transverse BTBT, as had been reported in the previous literature.</P>