Browsing by Author "Yeh, KL"

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A novel methodology for extracting effective density-of-states in poly-Si thin-film transistors
(2004)
Lin, HC
;
Yeh, KL
;
Lee, MH
;
Su, YC
;
Huang, TY
A novel methodology that greatly simplifies the procedure of extracting the effective density-of-states (DOS) in polycrystalline-Si thin-film transistors (poly-Si TFTs) is proposed and demonstrated. The characterization is performed on a Schottky barrier (SB) TFT with electrical source/drain extensions induced by a field-plate. Only one single device and two simple subthreshold I-V measurements at room temperature are needed for full band-gap DOS extraction. Impacts of different process treatments are clearly resolved using this methodology.
A novel thin-film transistor with self-aligned field induced drain
(2001-01-01)
Lin, HC
;
Yu, CM
;
Lin, CY
;
Yeh, KL
;
Huang, TY
In this letter, a novel thin-film transistor with a self-aligned field-induced-drain (SAFID) structure is reported for the first time. The new SAFID TFT features a self-aligned sidewall spacer located on top of the drain offset region to set its effective length, and a bottom gate (or field plate) situated under the drain offset region to electrically induce the field-induced-drain (FID). So, unlike the conventional off-set-gated TFTs with their effective FID length set by two separate photolithographic masking layers, the new SAFID is totally immune to photomasking misalignment errors, while enjoying the low off-state leakage as well as high turn-on characteristics inherent in the FID structure. Polycrystalline silicon TFTs with the new SAFID structure have been successfully fabricated with significant improvement in the on/off current ratio.
Ambipolar Schottky-barrier TFTs
(2002-02-01)
Lin, HC
;
Yeh, KL
;
Huang, TY
;
Huang, RG
;
Sze, SM
A novel Schottky-barrier metal-oxide-semiconductor thin-film transistor (SBTFT) was successfully demonstrated and characterized. The new SBTFT device features a fleld-induced-drain (FID) region, which is controlled by a metal field-plate lying on top of the passivation oxide. The FED region is sandwiched between the silicided drain and the active channel region. Carrier types and the conductivity of the transistor are controlled by the metal field-plate. The device is thus capable of ambipolar operation. Excellent ambipolar performance with on/off current ratios over 10(6) for both p- and n-channel operations was realized simultaneously on the same device fabricated with polysilicon active layer. Moreover, the off-state leakage current shows very weak dependence on the gate-to-drain voltage difference with the FID structure. Finally, the effects of FED length are explored.
Characteristics of Schottky barrier poly-Si thin film transistors with excimer laser annealing treatment
(2003)
Yeh, KL
;
Lin, HC
;
Tsai, RW
;
Lee, MH
;
Huang, TY
Poly-Si Schottky barrier poly-Si thin-film transistors (SB TFT) with field-induced drain (FID) have recently been demonstrated. Such devices exhibit ambipolar operation capability with low off-state leakage current. In this study, we investigate and compare the characteristics of poly-Si SB TFTs with channel layer prepared by either excimer laser crystallization (ELC) or solid-phase crystallization (SPC) method. It is shown that the use of ELC could greatly improve the device characteristics compared to the SPC counterparts. Excellent device performance in terms of steep subthreshold slope and high on/off current ratio (>10(8)) for both p- and n-channel operations are demonstrated on a single device with ELC channel. The effects of sub-gate bias, channel length, and offset channel length, on device characteristics are also explored.
Conduction mechanisms for off-state leakage current of Schottky barrier thin-film transistors
(2001-07-30)
Yeh, KL
;
Lin, HC
;
Huang, RG
;
Tsai, RW
;
Huang, TY
Conduction mechanisms for the off-state leakage in Schottky barrier thin-film transistor were explored. It was found that the field-emission process dominates the leakage conduction of the device with the conventional structure as the field strength in the drain junction becomes high, and results in the strong gate-induced drain leakage (GIDL) like phenomenon. In contrast, for the device with a field-induced-drain structure, the high-field region is pulled away from the silicided drain. As a result, the field-emission conduction is eliminated, so the GIDL-like leakage current is effectively suppressed. (C) 2001 American Institute of Physics.
Determination of effective density-of-states using a novel Schottky barrier poly-Si thin-film transistor
(2005)
Lin, HC
;
Lee, MH
;
Yeh, KL
;
Huang, TY
;
電子工程學系及電子研究所
We demonstrate that it is possible to extract the defect density distribution within the entire energy gap of a poly-Si layer by using a novel Schottky barrier thin-film transistor test structure. Our methodology, albeit based on the well-known field-effect conductance method, does not require two separate n- and p-channel test devices necessary in the conventional methods. This unique and much simplified single-test-device feature is made possible thanks to the ambipolar characteristics and the suppression of subthreshold leakage current in the new test scheme. Effects of process treatments such as plasma hydrogenation could also be clearly resolved using the new test structure. (c) 2005 The Electrochemical Society. All rights reserved.
Fabrication and characterization of Schottky barrier polysilicon thin-film transistors with excimer-laser crystallized channel
(2003-04-01)
Yeh, KL
;
Lin, HC
;
Tsai, RW
;
Lee, MH
;
Huang, TY
Schottky barrier thin-film transistors (SB TFT) with field-induced drain (FID) have recently been demonstrated to exhibit ambipolar capability with low off-state leakage current. In this study, we investigate and compare the characteristics of poly-Si SB TFTs with channel layer prepared by excimer laser crystallization (ELC) and solid-phase crystallization (SPC). It is shown that the use of ELC could greatly improve the device characteristics, comparing to the SPC counterparts. Excellent device performance with steep subthreshold slope and on/off current ratio higher than 10(8) for both p- and n-channel operations are demonstrated on a single device with ELC channel. The effects of sub-gate bias, channel length, and channel offset length, on device characteristics are also explored.
Reduction of off-state leakage current in Schottky barrier thin-film transistors (SBTFT) by a field-induced drain
(2002-04-01)
Yeh, KL
;
Lin, HC
;
Huang, RG
;
Tsai, RW
;
Huang, TY
Detailed conduction mechanisms in a conventional Schottky barrier thin-film transistor (SBTFT) and a recently proposed novel SBTFT with field-induced drain (FID) extension have been studied. The new SBTFT device with FID extension shows excellent ambipolar performance with effective suppression of gate-induced drain leakage (GIDL)-like off-state leakage that plagues conventional SBTFT devices. By characterizing the activation energy of the conduction process in the off-state for conventional SBTFT devices, it is suggested that field emission of carriers from the drain junction is the major conduction mechanism. While for the FID SBTFT devices, owing to the effect of Fermi level pinning in the FID region, thermionic emission rather than field emission becomes the dominant conduction mechanism, resulting in the effective suppression of the undesirable GIDL-like leakage current.
Schottky barrier thin-film transistor (SBTFT) with silicided source/drain and field-induced drain extension
(2001-04-01)
Lin, HC
;
Yeh, KL
;
Huang, RG
;
Lin, CY
;
Huang, TY
A novel Schottky barrier thin-film transistor (SBTFT) with silicided source/drain and field-induced drain (FID) extension is proposed and demonstrated. In the new device configuration, a metal field-plate (or sub-gate) lying on the passivation oxide is employed to induce a sheet of carriers in a channel offset region located between the silicided drain and the active channel region underneath the main-gate. The new device thus allows ambipolar device operation by simply switching the polarity of the bias applied to the field plate. In contrast to the conventional SBTFT that suffers from high GIDL (gate-induced drain leakage)-like off-state leakage current, the new SBTFT with FID is essentially free from the GIDL-like leakage current. In addition, unlike the conventional SBTFT that suffers from the low on-off current ratio, the new device exhibits high on/off current ratio up to 10(6) for both n- and p-channel modes of operation. Moreover, the implantless feature and the ambipolar capability of the new device also result in extra low mask count for CMOS processes integration. These excellent device characteristics, coupled with its simple processing, make the new device very promising for future large-area electronic applications.
Self-aligned fabrication of thin-film transistors with field-induced drain
(2002-08-01)
Yu, CM
;
Lin, HC
;
Lin, CY
;
Yeh, KL
;
Huang, TY
Thin-film transistor (TFT) devices with either a top or a bottom sub-gate were fabricated and characterized. The top sub-gate scheme allows the self-aligned formation of main-gate with respect to the sub-gate. On the other hand, the bottom sub-gate scheme features a self-aligned field-induced drain with a sidewall spacer located on its top to set the effective field-induction-drain (FID) length. Unlike the conventional TFTs, the FID serves to distribute the high drain electric field and thereby eliminates gate-induced drain leakage-like off-state leakage current. Superior device performance is realized with the bottom sub-gate structure. (C) 2002 Elsevier Science Ltd. All rights reserved.