• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.323-324
• /
• 2009

We investigated the electrical properties of tris-isopropylsilylethynyl (TIPS)-pentacene organic thin-film transistors (OTFTs) employing Ni/Ag source/drain electrodes. The gap height between the gate insulator and S/D electrode was controlled by changing the thickness of Ag under-layer(20, 30, 40 and 50nm). After evaporating the Ni under-layer, TIPS pentacene channel material was dropping the gap between the gate insulator and SID electrodes. The electrical proprieties of OTFT such as filed-effect mobility, on/off ratio, threshold voltage and subthreshold slope were significantly influenced by the gap height.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.730-732
• /
• 2007

We fabricated a coplanar type organic thin-film transistors using ink-jet printed silver source/drain electrodes and ${\alpha},{\omega}-dihexylquaterthiophene$ (DH4T) which is an active layer. Use of ink-jet printed silver nanoparticle-based metal electrode assists the energetic mismatch with p-type organic semiconductor via modification of their interfacial properties to enable ohmic contact formation.

• Journal of Information Display
• /
• v.12 no.4
• /
• pp.213-217
• /
• 2011

Printing technologies were applied to fabricate a flexible organic thin-film transistor (OTFT) backplane for electrophoretic displays (EPDs). Various printing processes were adopted to maximize the figures of each layer of OTFT: screen printing combined with reverse offset printing for the gate electrodes and scan bus lines with Ag ink, inkjet for the source/drain electrodes with glycerol-doped Poly (3,4-ethylenedioxythiophene): Poly (styrenesulfonate) (PEDOT:PSS), inkjet for the semiconductor layer with Triisopropylsilylethynyl (TIPS)-pentacene, and screen printing for the pixel electrodes with Ag paste. A mobility of $0.44cm^2/V$ s was obtained, with an average standard deviation of 20%, from the 36 OTFTs taken from different backplane locations, which indicates high uniformity. An EPD laminated on an OTFT backplane with $190{\times}152$ pixels on an 8-in panel was successfully operated by displaying some patterns.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.3
• /
• pp.7-11
• /
• 2011

In this paper, we proposed a simple and high-yield printing process for source and drain electrodes of organic thin film transistor (OTFT). The surface energy of PVP (poly 4-vinylphenol) gate dielectric was decreased from 56 $mJ/m^2$ to 45 $mJ/m^2$ by adding fluoride of 3000ppm into it. Meanwhile the surface energy of source and drain (S/D) electrodes area on the PVP was increased to 87 $mJ/m^2$ by treating the areas, which was patterned by photolithography, with oxygen plasma, maximizing the surface energy difference from the other areas. A conductive polymer, G-PEDOT:PSS, was deposited on the S/D electrode areas by brushing painting process. With such a simple process we could obtain a high yield of above 90 % in $16{\times}16$ arrays of OTFTs. The performance of OTFTs with the fluoride-added PVP was similar to that of OTFTs with the ordinary PVP without fluoride, generating the mobility of 0.1 $cm^2/V.sec$, which was sufficient enough to drive electrophoretic display (EPD) sheet. The EPD panel employing the OTFT-backpane successfully demonstrated to display some patterns on it.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.1463-1465
• /
• 2008

We report all-ink-jet printed inorganic/organic hybrid TFTs on plastic substrates. We have investigated the optimal printing conditions to make uniform patterned layers of gate electrode, dielectrics, source/drain electrodes, and semiconductor as a coplanar type TFT in a successive manner. All ink-jet printed devices have good mechanical flexibility and current modulation characteristic even when bent.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.875-877
• /
• 2007

Zinc tin oxide (ZTO) sol-gel solution was synthesized for ink-jet printable semiconducting ink. Bottom-contact type TFT was produced by printing the ZTO layer between the source and drain electrodes. The transistor involving the ink-jet printed ZTO had the $mobility\;{\sim}\;0.01\;cm^2V^{-1}s^{-1}$. We demonstrated the direct-writing of semiconducting oxide for solution processed TFT fabrication.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.395-395
• /
• 2007

We report on the fabrication of soluble pentacene-based thin-film transistors (TFTs) that consist of $NiO_x$, poly-vinyl phenol (PVP), and Ni for the source-drain (SID) electrodes, gate dielectric, and gate electrode, respectively. The $NiO_x$ SID electrodes of which the work function is well matched to that of soluble pentacene are deposited on a soluble pentacenechannel by sputter deposited of NiO powder and show a moderately low but still effective transmittance of ~65% in the visible range along with a good sheet resistance of ${\sim}40{\Omega}/{\square}$. The maximum saturation current of our soluble pentacene-based TFT is about $15{\mu}A$ at a gate bias of -40showing a high field effect mobility of $0.06cm^2/Vs$ in the dark, and the on/off current ratio of our TFT is about $10^4$. It is concluded that jointly adopting $NiO_x$ for the S/D electrodes and PVP for gate dielectric realizes a high-quality soluble pentacene-based TFT.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.19 no.12
• /
• pp.1140-1143
• /
• 2006

We report on the fabrication of P3HT-based thin-film transistors (TFTs) for liquid crystal display that consist of $NiO_x$, poly-vinyl phenol (PVP), and Ni for the source-drain (S/D) electrodes, gate dielectric layer, and gate electrode, respectively The $NiO_x$ S/D electrodes of which the work function is well matched to that of P3HT are deposited on a P3HT channel by electron-beam evaporation of NiO powder. The maximum saturation current of our P3HT-based TFT is about $15{\mu}A$ at a gate bias of -30 V showing a high field effect mobility of $0.079cm^2/Vs$ in the dark, and the on/off current ratio of our TFT is about $10^5$. It is concluded that jointly adopting $NiO_x$ for the S/D electrodes and PVP for gate dielectric realizes a high-quality P3HT-based TFT.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.506-508
• /
• 2005

In general, organic TFTs are comprised of four components: gate electrode, gate dielectric, organic active semiconductor layer, and source and drain contacts. The TFT current, in turn, is typically determined by channel length and width, carrier field effect mobility, gate dielectric thickness and permittivity, contact resistance, and biasing conditions. More recently, a number of techniques and processes have been introduced to the fabrication of OTFT circuits and displays that aim specifically at reduced fabrication cost. These include microcontact printing for the patterning of metals and dielectrics, the use of photochemically patterned insulating and conducting films, and inkjet printing for the selective deposition of contacts and interconnect pattern. In the fabrication of organic TFTs, microcontact printing has been used to pattern gate electrodes, gate dielectrics, and source and drain contacts with sufficient yield to allow the fabrication of transistors. We were fabricated a pentacene OTFTs on flexible PEN film. Au/Cr was used for the gate electrode, parylene-c was deposited as the gate dielectric, and Au/Cr was chosen for the source and drain contacts; were all deposited by ion-beam sputtering and patterned by microcontact printing and lift-off process. Prior to the deposition of the organic active layer, the gate dielectric surface was treated with octadecyltrichlorosilane(OTS) from the vapor phase. To complete the device, pentacene was deposited by thermal evaporation and patterned using a parylene-c layer. The device was shown that the carrier field effect mobility, the threshold voltage, the subthreshold slope, and the on/off current ratio were improved.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.25-26
• /
• 2011

In this paper, we investigated the effect of various annealing processes on the electrical characteristics of oxide thin film transistors (TFTs). When we annealed the TFT devices before and after source/drain (S/D) process, we could observe the different electrical characteristics of oxide TFTs. When we annealed the TFTs after deposition of transparent indium zinc oxide S/D electrodes, the annealing process decreased the contact resistance but increased the resistivity of S/D electrodes. The field effect mobility, subthreshold slope and threshold voltage of the oxide TFTs annealed before and after S/D process were 5.83 and 4.47 $cm^2$/Vs, 1.20 and 0.82 V/dec, and 3.92 and 8.33 V respectively. To analyze the differences, we measured the contact resistances and the carrier concentrations using transfer length method (TLM) and Hall measurement.