Browsing by Author "Yu, MC"

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A physical model for hole direct tunneling current in P+ poly-gate PMOSFETs with ultrathin gate oxides
(2000-11-01)
Yang, KN
;
Huang, HT
;
Chang, MC
;
Chu, CM
;
Chen, YS
A model of the hole direct tunneling gate current accounting for heavy and light hole's subbands in the quantized inversion layer is built explicitly. This model comprises four key physical parameters: inversion layer charge density, hole impact frequency on SiO2/Si interface, WKB transmission probability, and reflection correction factor. With the effective hole mass m(oxh) = 0.5m(o) for parabolic dispersion relationship in the oxide, experimental reproduction without any parameter adjustment is consistently achieved in p(+) poly-gate pMOSFETs with 1.23, 1.85, and 2.16 nm gate oxide thicknesses. The proposed model can thereby serve as a promising characterization means of direct tunnel oxides. In particular, it is calculated that the secondary subbands and beyond, although occupying few holes, indeed contribute substantially to the direct tunneling conduction due to effective lo,vcr barrier heights, and are prevailing over the first subbands for reducing oxide field down below 1 MV/cm.
Characterization and modeling of edge direct tunneling (EDT) leakage in ultrathin gate oxide MOSFETs
(2001-06-01)
Yang, KN
;
Huang, HT
;
Chen, MJ
;
Lin, YM
;
Yu, MC
This paper examines the edge direct tunneling (EDT) of electron from n(+) polysilicon to underlying n-type drain extension in off-state n-channel MOSFET's having ultrathin gate oxide thicknesses (1.4-2.4 mm), It is found that for thinner oxide thicknesses, electron EDT is more pronounced over the conventional gate-induced-drain-leakage (GIDL), bulk band-to-band tunneling (BTBT), and gate-to-substrate tunneling, and as a result, the induced gate and drain leakage is better measured per unit gate width. A physical model is for the first time derived for the oxide field fox at the gate edge by accounting for electron subband in the quantized accumulation polysilicon surface. This model relates fox to the gate-to-drain voltage, oxide thickness, and doping concentration of drain extension, Once fox is known, an existing DT model readily reproduces EDT I-V consistently and the tunneling path size extracted falls adequately within the gate-to-drain overlap region. The ultimate oxide thickness limit due to EDT is projected as well.
Edge hole direct tunneling in off-state ultrathin gate oxide p-channel MOSFETs
(2000)
Yang, KN
;
Huang, HT
;
Chen, MJ
;
Lin, YM
;
Yu, MC
This paper examines the edge direct tunneling (EDT) of hole from p(+) polysilicon to underlying p-type drain extension in off-state p-channel MOSFETs having ultrathin gate oxide thicknesses (1.2 - 2.2 nm). It is found that for thinner oxide thicknesses, hole EDT is more pronounced over the conventional GIDL and gate-to-channel tunneling, and as a result, the induced gate and drain leakage is better measured per unit gate width. A physical model accounting for heavy and light hole's subbands in the quantized accumulation polysilicon surface is built explicitly. This model consistently reproduces EDT I-V and the tunneling path size extracted falls adequately within the gate-to-drain overlap region. The ultimate oxide thickness limit due to EDT is projected as well.
Edge hole direct Tunneling leakage in ultrathin gate oxide p-channel MOSFETs
(2001-12-01)
Yang, KN
;
Huang, HT
;
Chen, MJ
;
Lin, YM
;
Yu, MC
This paper examines the edge direct tunneling (EDT) of holes from p(+) polysilicon to underlying p-type drain extensions in off-state p-channel MOSFETs having ultrathin gate oxides that are 1.2 nm-2.2 nm thick. It is for the first time found that for thinner oxides, hole EDT is more pronounced than both conventional gate-induced drain leakage (GIDL) and gate-to-channel tunneling. As a result, the induced gate and drain leakage is more accurately measured per unit gate width. Terminal currents versus input voltage are measured from a CMOS inverter with gate oxide thickness T-OX = 1.23 nm, exhibiting the impact of EDT in two standby modes. For the first time, a physical model is derived for the oxide field E-OX at the gate edge by accounting for the heavy and light holes' subbands in the quantized accumulation polysilicon surface. This model relates E-OX to the gate-to-drain voltage, oxide thickness, and doping concentration of the drain extension. Once E-OX is known, an existing direct tunneling (DT) model consistently reproduces EDT current-voltage (I-V), and the tunneling path size extracted falls adequately within the gate-to-drain overlap region. The ultimate oxide thickness limit due to hole EDT is projected.
Inhibition of hepatitis C virus replication by antimonial compounds
(2005-10-01)
Hwang, DR
;
Lin, RK
;
Leu, GZ
;
Lin, TY
;
Lien, TW
Chronic hepatitis C virus (HCV) infection is a worldwide health problem causing serious complications, such as liver cirrhosis and hepatoma. Alpha interferon (IFN-alpha) or its polyethylene glycol-modified form combined with ribavirin is the only recommended therapy. However, an alternative therapy is needed due to the unsatisfactory cure rate of the IFN-based therapy. Using a modified reporter assay based on the HCV subgenomic-replicon system, we found that sodium stibogluconate (SSG), a compound used for leishmania treatment, suppressed HCV replication. We have previously reported that SSG is effective at inhibiting HCV replication in a cell line permissive for HCV infection/replication and in an ex vivo assay using fresh human liver slices obtained from patients infected with HCV (26). In this study, we show that the SSG 50% inhibitory dose for HCV replication is 0.2 to 0.3 mg/ml (equivalent to 345 to 517 mu M of Sb) in the HCV subgenomic-replicon system. We also found that SSG and IFN-alpha exert a strong synergistic anti-HCV effect in both the traditional isobologram analysis and the median effect principle (CalcuSyn analysis). The combination of SSG and IFN-alpha could sustain the antiviral response better than SSG or IFN-alpha alone. The results suggest that SSG may be a good drug candidate for use in combination with other therapeutics, such as IFN-alpha and ribavirin, to treat HCV infection.