Browsing by Author "Lin, Cheng-I"

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Characteristics of n-Type Junctionless Poly-Si Thin-Film Transistors With an Ultrathin Channel
(2012-01-01)
Lin, Horng-Chih
;
Lin, Cheng-I
;
Huang, Tiao-Yuan
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this letter, we study the characteristics of n-type junctionless (JL) poly-Si thin-film transistors (TFTs) with an ultrathin and heavily phosphorous doped channel. The fabricated devices show excellent performance with a subthreshold swing of 240 mV/dec and an on/off current ratio of > 10(7). Moreover, the JL device shows 23 times increase in the ON-state current at a gate overdrive of 4 V as compared with the conventional control device with an undoped channel. The significant improvement in the current drive is ascribed to the inherently high carrier concentration contained in the channel of the JL device. These results evidence the great potential of the JL poly-Si TFTs for the manufacturing of future 3-D and flat-panel electronic products.
Characteristics of Planar Junctionless Poly-Si Thin-Film Transistors With Various Channel Thickness
(2013-03-01)
Lin, Horng-Chih
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Lin, Cheng-I
;
Lin, Zer-Ming
;
Shie, Bo-Shiuan
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Huang, Tiao-Yuan
N-type junctionless (JL) planar poly-Si thin-film transistors (TFTs), which contain an in situ heavily phosphorous-doped channel with thickness ranging from 8 to 12 nm, were fabricated and characterized. The devices exhibit superior current drive and good control over performance variability. From C-V characterization, the ionized dopant concentration in the channel is determined to be around 2 x 10(19) cm(-3) and the fixed charge density to be around -6 x 10(12) cm(-2). The negative fixed charge density is probably related to the segregation of phosphorous species at the oxide/channel interface. We also observed a reverse short-channel effect from the relationship between the threshold voltage and the channel length. One mechanism considering enhanced phosphorous segregation is proposed to explain this finding.
Effects of the Variation of Ferroelectric Properties on Negative Capacitance FET Characteristics
(2016-05)
Lin, Cheng-I
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Khan, Asif Islam
;
Salahuddin, Sayeef
;
Hu, Chenming
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電子工程學系及電子研究所
We study the effects of the variation of ferroelectric material properties (thickness, polarization, and coercivity) on the performance of negative capacitance FETs (NCFETs). Based on this, we propose the concept of conservative design of NCFETs, where any unintentional yet reasonable and simultaneous variation (similar to +/- 3%) in ferroelectric parameters does not result in the emergence of hysteresis and causes only a reasonable variation in the ON-current (<= 5%) and, within these constraints, the enhancement of ON-current due to the addition of the ferroelectric gate oxide, which is is maximized.
Electrical characteristics of amorphous In-Ga-Zn-O thin-film transistors prepared by radio frequency magnetron sputtering with varying oxygen flows
(2014-07-01)
Lee, Yih-Shing
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Yen, Tung-Wei
;
Lin, Cheng-I
;
Lin, Horng-Chih
;
Yeh, Yun
This study investigates impacts of oxygen flow during the deposition of amorphous indium-gallium-zinc oxide (a-IGZO) channel layer with a radio frequency (r.f.) magnetron sputter on the electrical characteristics of the fabricated thin-film transistors (TFTs). Results indicate that as the film was deposited with a higher oxygen flow, the transfer curves are positively shifted while the field-effect mobility (mu(FE)) is significantly decreased. To get more insight about the effects, channel resistance (R-CH) and the parasitic source-to-drain resistance (R-SD) of the fabricated devices are extracted using the total resistance method. The extracted a-IGZO channel resistance per unit length (r(ch)) and R-SD are found to increase while the extracted effective mobility (mu(E)) is decreased with increasing oxygen flow during sputtering. These observations are postulated to be related the decrease in the In/(In + Ga + Zn) ratio and the increase in the Zn/(In + Ga + Zn) ratio of the a-IGZO films with increasing the oxygen flow rate which lead to higher resistivity and lower carrier concentration. The extracted R-SD can be comparable with R-CH for the devices prepared with high oxygen flow, resulting in the roll-off of mu(FE) as the channel length is shorter than 20 mu m. (C) 2014 Elsevier B.V. All rights reserved.
Electrical characteristics of amorphous In-Ga-Zn-O thin-film transistors prepared by radio frequency magnetron sputtering with varying oxygen flows
(2014-07-01)
Lee, Yih-Shing
;
Yen, Tung-Wei
;
Lin, Cheng-I
;
Lin, Horng-Chih
;
Yeh, Yun
This study investigates impacts of oxygen flow during the deposition of amorphous indium-gallium-zinc oxide (a-IGZO) channel layer with a radio frequency (r.f.) magnetron sputter on the electrical characteristics of the fabricated thin-film transistors (TFTs). Results indicate that as the film was deposited with a higher oxygen flow, the transfer curves are positively shifted while the field-effect mobility (mu(FE)) is significantly decreased. To get more insight about the effects, channel resistance (R-CH) and the parasitic source-to-drain resistance (R-SD) of the fabricated devices are extracted using the total resistance method. The extracted a-IGZO channel resistance per unit length (r(ch)) and R-SD are found to increase while the extracted effective mobility (mu(E)) is decreased with increasing oxygen flow during sputtering. These observations are postulated to be related the decrease in the In/(In + Ga + Zn) ratio and the increase in the Zn/(In + Ga + Zn) ratio of the a-IGZO films with increasing the oxygen flow rate which lead to higher resistivity and lower carrier concentration. The extracted R-SD can be comparable with R-CH for the devices prepared with high oxygen flow, resulting in the roll-off of mu(FE) as the channel length is shorter than 20 mu m. (C) 2014 Elsevier B.V. All rights reserved.
Fabrication of tri-gated junctionless poly-Si transistors with I-line based lithography
(2014-04-01)
Lin, Cheng-I
;
Lee, Ko-Hui
;
Lin, Horng-Chih
;
Huang, Tiao-Yuan
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電機工程學系
In this work, we have successfully demonstrated the feasibility of a method, which relies solely on I-line-based lithography, for fabricating sub-100nm tri-gated junctionless (JL) poly-Si nanowire (NW) transistors. This method employs sidewall spacer etching and photoresist (PR) trimming techniques to shrink the channel length and width, respectively. With this approach, channel length and width down to 90 and 93nm, respectively, are achieved in this work. The fabricated devices exhibit superior device characteristics with low subthreshold swing of 285mV/dec and on/off current ratio larger than 10(7). (C) 2014 The Japan Society of Applied Physics
Relationships between the crystalline phase of an IGZO target and electrical properties of a-IGZO channel film
(2012-01-01)
Lee, Yih-Shing
;
Dai, Zuo-Ming
;
Lin, Cheng-I
;
Lin, Horng-Chih
;
電子工程學系及電子研究所
This study used powders containing different In2O3-Ga2O3-ZnO (IGZO) chemical compositions to manufacture targets using a metallurgical process. The resulting targets were used to deposit amorphous In-Ga-Zn-O (a-IGZO) channel films by a radio frequency magnetron sputtering process. This study examined the relationships between these target compositions and crystalline phases of the powders and the resulting material characterization, examining the impacts on electrical characteristics of a-IGZO films with varied O-2 flow rates. The ternary compound phase of ZnGa2O4 became stable at 1000 degrees C according to XRD diagrams at different calcining temperatures. An analysis of the XRD diagrams of different compositions of IGZO powders showed that the atomic ratio of ZnO is larger than that of In2O3 and Ga2O3, and that the main peaks (1 0 1) and (0 0 15) intensity of the respective InGaZnO4 and lnGaZnO6 phases intensity would increase. Ceramic targets with different compositions were used to deposit the a-IGZO films with varied O-2 flow rates. When the O-2 flow rate was zero, the results of a Hall measurement of a-IGZO films deposited from targets with higher Zn atomic ratio showed lower resistivity, higher carrier concentration, and lower mobility. Nevertheless, as the O-2 flow rate was more than 5 sccm, increasing the atom ratio of Zn in the IGZO ceramic target obviously increased the capability of capturing O-2 in the a-IGZO films, leading to higher resistivity, lower carrier concentration (<10(18) cm(-3)), and higher mobility. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
The Degradation of MILC P-Channel Poly-Si TFTs under Dynamic Hot-Carrier Stress Using a Novel Test Structure
(2011)
Lin, Cheng-I
;
Hong, Wen-Chiang
;
Lin, Tin-Fu
;
Lin, Horng-Chih
;
Huang, Tiao-Yuan
In this study, dynamic hot carrier effect in the MILC p-channel TFT device has been characterized by the unique struture. This novel structure is capable of spatially resolving the hot carrier effect and is highly sensitive to detect the defect-rich region. The dynamic hot carrier stress has been focused on the impacts of the frequency, the rise time and the fall time. In varied frequency stress condition, the degradation in the drain-sided monitor transistor (DMT) increases monotonically with increasing frequency, infering that more defects are generated by extra dynamic stress contribution in the drain side and degrade the characteristic of device. Under varied fall time stress condition, the on-current degradtion is severe with decreasing fall time due to the extra voltage drop during voltage switch. The final part is effect of rise time. While device switches, the large voltage drop exists in the junction between the channel and the drain, which resulted in anothor hot carrier degradation.