• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1334_1335
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• 2009

In this paper we have presented recent studies concerning the high performance oxide thin film transistor (TFT) with a-IGZO channel and $ZrO_2$ gate dielectrics. The a-IGZO TFT is fully fabricated at room-temperature without any thermal treatments. The $ZrO_2$ is one of the most promising high-k materials with high capacitance originated from the high dielectric constant. The a-IGZO TFT with $ZrO_2$ shows high performance exhibiting high field effect mobility of $39.82\;cm^2$/Vs and high on-current of 2.52 mA at 10V.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.703-706
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• 2006

Zinc oxide nanocrystals are attractive candidates for a solution-processable semiconductor for high performance thin film field effect transistors. We have studied ZnO thin film transistor fabricated by solution process and have improved $V_{th}$ by controlling the ZnO ink additives. Synthesized ZnO nanoparticles of 30nm were dispersed in solvent to make the ZnO ink. ZnO ink was spin coated on silicon wafer and after heat treatment electrodes were patterned.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.957-961
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• 2004

In order to realize high performance thin film transistor (TFT) on plastic substrate, Si film was deposited on plastic substrate at 170$^{\circ}C$ by using inductivity coupled plasma chemical vapor deposition (ICPCVD). Hydrogen concentration in as-deposited Si film was 3.8% which is much lower than that in film prepared by using conventional plasma enhanced chemical vapor deposition (PECVD). Si film was deposited as micro crystalline phase rather than amorphous phase even at 170$^{\circ}C$ because of high density plasma. By step-by-step Excimer laser annealing, dehydrogenation and recrystallization of Si film were carried out simultaneously. With step-by-step annealing and optimization of underlayer structure, it has succeeded to achieve large grain size of 300nm by using ICPCVD. Base on these results, poly-Si TFT was fabricated on plastic substrate successfully, and it is sufficient to drive pixels of OLEDs, as well as LCDs.

• 반도체디스플레이기술학회지
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• 제13권3호
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• pp.35-38
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• 2014

Flat panel displays fabricated on glass substrate use amorphous Si for data processing circuit. Recent progress in display technology requires a new material to replace the amorphous Si, and ZnO is a good candidate. ZnO is a wide bandgap (3.3 eV) semiconductor with high mobility and good optical transparency. ZnO is usually grown by sputtering using ZnO ceramic target. However, ceramic target is more expensive than metal target, and making large area target is very difficult. In this work we studied characteristics of ZnO thin-film transistor grown by rf sputtering using Zn metal target and $CO_2$. ZnO film was grown at $450^{\circ}C$ substrate temperature, with -70 V substrate bias voltage applied. By using these methods, our ZnO TFT showed $5.2cm^2/Vsec$ mobility, $3{\times}10^6$ on-off ratio, and -7 V threshold voltage.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.523-525
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• 2002

The poly-Si thin film can be used in high mobility active matrix liquid-crystal display (AMLCD) and system on panel (SOP). In this paper, poly-Si thin films were grown by novel high temperature process on the molybdenum (Mo) substrate. By applying a high current above 48A on a Mo substrate. We obtained an improved crystalline Si films with the crystallinity over 80%. We exhibit the properties of structural and electrical properties of high temperature poly-Si thin film transistor on the Mo substrates.

• 한국재료학회지
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• 제18권9호
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• pp.507-510
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• 2008

Electrical properties of multi-channel metal-induced unilaterally precrystallized polycrystalline silicon thin-film transistor (MIUP poly-Si TFT) devices and circuits were investigated. Although their structure was integrated into small area, reducing annealing process time for fuller crystallization than that of conventional crystal filtered MIUP poly-Si TFTs, the multi-channel MIUP poly-Si TFTs showed the effect of crystal filtering. The multi-channel MIUP poly-Si TFTs showed a higher carrier mobility of more than 1.5 times that of the conventional MIUP poly-Si TFTs. Moreover, PMOS inverters consisting of the multi-channel MIUP poly-Si TFTs showed high dynamic performance compared with inverters consisting of the conventional MIUP poly-Si TFTs.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.595-596
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• 2006

The flexible organic thin film transistor (OTFT) array to use as a switching device for an organic light emitting diode (OLED) was designed and fabricated in the microcontact printing and low-temperature processes. The gate, source, and drain electrode patterns of OTFT were fabricated by microcontact printing which is high-resolution lithography technology using polydimethylsiloxane(PDMS) stamp. The OTFT array with dielectric layer and organic active semiconductor layers formed at room temperature or at a temperature tower than $40^{\circ}C$. The microcontact printing process using SAM(self-assembled monolayer) and PDMS stamp made it possible to fabricate OTFT arrays with channel lengths down to even nano size, and reduced the procedure by 10 steps compared with photolithography. Since the process was done in low temperature, there was no pattern transformation and bending problem appeared. It was possible to increase close packing of molecules by SAM, to improve electric field mobility, to decrease contact resistance, and to reduce threshold voltage by using a big dielecric.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.17.2-17.2
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• 2010

Printed electronics is an emerging technology to realize various microelectronic devices via a cost-effective method. Here we demonstrated a high performance of p-channel and n-channel top-gate/bottom contact polymer field-effect transistors (FETs), and applications to elementary organic complementary inverter and ring oscillator circuits by inkjet processing. We could obtained high field-effect mobility more than $0.4\;cm^2/Vs$ for both of p-channel and n-channel FETs, and successfully measured inkjet-printed polymer inverters. The performance of devices highly depends on the selection of dielectrics, printing condition and device architecture. Optimized CMOS ring oscillators with p-type and n-type polymer transistors showed as high as 50 kHz operation frequency. This research was financially supported by development of next generation RFID technology for item level applications (2008-F052-01) funded by the ministry of knowledge economy (MKE).

• 한국전기전자재료학회논문지
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• 제21권1호
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• pp.1-4
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• 2008

The electrical characteristics of polycrystalline silicon (poly-Si) thin film transistor (TFT) crystallized by excimer laser annealing (ELA) method were evaluated, The polycrystalline silicon thin-film transistor (poly-Si TFT) has higher electric field-effect-mobility and larger drivability than the amorphous silicon TFT. However, to poly-Si TFT's using conventional processes, the temperature must be very high. For this reason, an amorphous silicon film on a buried oxide was crystallized by annealing with a KrF excimer laser (248 nm)to fabricate a poly-Si film at low temperature. Then, High permittivity $HfO_2$ of 20 nm as the gate-insulator was deposited by atomic layer deposition (ALD) to low temperature process. In addition, the solid phase crystallization (SPC) was compared to the ELA method as a crystallization technique of amorphous-silicon film. As a result, the crystallinity and surface roughness of poly-Si crystallized by ELA method was superior to the SPC method. Also, we obtained excellent device characteristics from the Poly-Si TFT fabricated by the ELA crystallization method.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.106-106
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• 2011

Recently, zinc oxide (ZnO) thin films have attracted great attention as a promising candidate for various electronic applications such as transparent electrodes, thin film transistors, and optoelectronic devices. ZnO thin films have a wide band gap energy of 3.37 eV and transparency in visible region. Moreover, ZnO thin films can be deposited in a poly-crystalline form even at room temperature, extending the choice of substrates including even plastics. Therefore, it is possible to realize thin film transistors by using ZnO thin films as the active channel layer. In this work, we investigated influence of oxygen partial pressure on ZnO thin films and fabricated ZnO-based thin film transistors. ZnO thin films were deposited on glass substrates by using a pulsed laser deposition technique in various oxygen partial pressures from 20 to 100 mTorr at room temperature. X-ray diffraction (XRD), transmission line method (TLM), and UV-Vis spectroscopy were employed to study the structural, electrical, and optical properties of the ZnO thin films. As a result, 80 mTorr was optimal condition for active layer of thin film transistors, since the active layer of thin film transistors needs high resistivity to achieve low off-current and high on-off ratio. The fabricated ZnO-based thin film transistors operated in the enhancement mode with high field effect mobility and low threshold voltage.