• 한국전기전자재료학회논문지
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• 제16권12S호
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• pp.1175-1180
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• 2003

Transformer Coupled Plasma Chemical Vapor Deposited (TCP-CVD) silicon nitride (SiNx) is widely used as a gate dielectric material for thin film transistors (TFT). This paper reports the SiNx films, grown by TCP-CVD at the low temperature (30$0^{\circ}C$). Experimental investigations were carried out for the optimization o(SiNx film as a function of $N_2$/SiH$_4$ flow ratio varying ,3 to 50 keeping rf power of 200 W, This paper presents the dielectric studies of SiNx gate in terms of deposition rate, hydrogen content, etch rate and leakage current density characteristics lot the thin film transistor applications. And also, this work investigated means to decrease the leakage current of SiNx film by employing $N_2$ plasma treatment. The insulator layers were prepared by two step process; the $N_2$ plasma treatment and then PECVD SiNx deposition with SiH$_4$, $N_2$gases.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.169-172
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• 2000

A-Si:H and poly-Si TFT characteristics were investigated using an inverted staggered type TFT. The poly-Si films were achieved by various anneal techniques ; isothermal, RTA, and excimer laser anneal. The TFT on as-grown a-Si:H exhibited a low field effect mobility, transconductance, and high gate threshold voltage. Some films were annealed at temperatures from $200^{\circ}C$ to $1000^{\circ}C$. The TFT on poly-Si showed an improved $I_{on}/I_{off}$ ratio of $10^6$, reduced gate threshold voltage, and increased field effect mobility by three orders. Inverter operation was examined to verify logic circuit application using the poly-Si TFTs.

• 한국전기전자재료학회논문지
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• 제16권1호
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• pp.26-32
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• 2003

Then-channel poly-Si thin-film transistors (poly-Si TFT's) formed by solid phase crystallization (SPC) method on glass were measured to obtain the electrical parameters such as of I-V characteristics, mobility, leakage current, threshold voltage, and subthreshold slope. Then, devices were analyzed to obtain the reliability and appliability on TFT-LCD with large-size and high density. In n-channel poly-Si TFT with 5$\mu\textrm{m}$/2$\mu\textrm{m}$, 8$\mu\textrm{m}$, 30$\mu\textrm{m}$ devices of channel width/length, the field effect mobilities are 111, 116, 125 $\textrm{cm}^2$/V-s and leakage currents are 0.6, 0.1, and 0.02 pA/$\mu\textrm{m}$, respectively. Low threshold voltage and subthreshold slope, and good ON-OFF ratio are shown, as well. Thus. the poly-Si TFT's used by SPC are expected to be applied on TFT-LCD with large-size and high density, which can integrate the display panel and peripheral circuit on a targe glass substrate.

• Journal of information and communication convergence engineering
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• 제2권2호
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• pp.93-96
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• 2004

The a-Si:H TFT using ferroelectric of $SrTiO_3$ as a gate insulator is fabricated on glass. Dielectric characteristics of ferroelectric are superior to $SiO_2$ and $Si_{3}N_{4}$. Ferroelectric increases on-current, decreases threshold voltage of TFT and also improves breakdown characteristics. The a-SiN:H has optical band gap of 2.61 eV, retractive index of 1.8∼2.0 and resistivity of $10^{13}$~$10^{15}$ $\Omega$cm, respectively. Insulating characteristics of ferroelectrics are excellent because dielectric constant of ferroelectric is about 60∼100 and breakdown strength is over 1MV/cm. TFT using ferroelectric has channel length of 8∼20 $\mu\textrm{m}$ and channel width of 80∼200 $\mu\textrm{m}$. And it shows that drain current is 3.4$\mu\textrm{A}$ at 20 gate voltage, $I_{on}$/$I_{off}$ is a ratio of $10^5$~$10^8$ and $V_{th}$ is 4∼5 volts, respectively. In the case of TFT without ferroelectric, it indicates that the drain current is 1.5 $\mu\textrm{A}$ at 20 gate voltage and $V_{th}$ is 5∼6 volts. With the improvement of the ferroelectric thin film properties, the performance of TFT using this ferroelectric has advanced as a gate insulator fabrication technology is realized.

• 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.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1463-1465
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• 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
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.754-758
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• 2002

In order to reach the high quality of organic thin films such as high mobility for device applications, it is strongly desirable to study the growth properties of pentacene film as a function of evaporation condition. Here, we report the structure and morphology of thermal evaporated pentacene thin film by AFM, SEM, and XRD as a function of the evaporation rate and substrate temperature. These results play a key role in determining the electric performance of organic thin film transistor devices.

• 한국산학기술학회논문지
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• 제8권4호
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• pp.738-742
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• 2007

능동형 평판디스플레이 소자를 제작하기 위해 수소화된 비정질 규소 박막트랜지스터 (a-Si:H TFT)의 상부에 화소전극을 형성하는 과정에 따른 TFT의 특성 변화를 연구하였다. 화소전극 형성 전에 1 pA 수준의 오프상태 전류 및 $10^6$ 이상의 스위칭률을 보이던 TFT에 화소전극 공정을 행하면 오프상태 전류가 10 pA 이상으로 증가하여 소자특성이 악화되었다. 이러한 소자특성의 악화는 SiNx 보호막 표면의 플라즈마 처리로 개선될 수 있었는데, 특히 $N_2$ 플라즈마가 좋은 결과를 보였다. 화소전극 공정에 의해서 누설전류가 증가하는 것은 투명전도막 증착공정 중에 SiNx 보호막 표면에 전하가 축적되어 이에 유도되는 백채널의 캐리어 축적에 기인하는 것으로 추정된다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.112.1-112.1
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• 2012

산화물 기반의 TFT (Thin Film Transistor) 는 유리, 금속, 플라스틱 등 기판 종류에 상관없이 균일한 제작이 가능하며, 상온 및 저온에서 대면적으로 제작이 가능하고, 저렴한 비용으로 제작 가능하다는 장점 때문에 최근 많은 연구가 이루어지고 있다. 현재 TFT 물질로 많이 연구되고 있는 산화물 중 가장 많은 연구가 이루어진 ZnO 기반의 TFT는mobility와 switching 속도에서 우수한 특성을 보이나, 트렌지스터의 안정성이 떨어지는 것으로 보고되고 있다. 그러나 a-IGZO의 경우 결정학적으로 비정질이며, 상온 및 저온에서 대면적으로 제작이 가능하고, 높은 전자 이동도의 특성을 가지고 있는 장점 때문에 최근 차세대 산화물 트렌지스터로 각광받고 있다. IGZO 물질의 경우 s 오비탈의 중첩으로 인해 높은 전자 이동도의 특성을 가지며, IGZO 물질 내 전자의 이동은 IGZO의 조성과 구조적 특성에 영향을 받는다. IGZO 물질의 구성 성분은 $In_2O_3$, $Ga_2O_3$, ZnO 성분으로 이루어져 있으며, $In_2O_3$의 경우 주로 carrier 를 생성하고 IGZO TFT의 mobility를 향상시키는 물질로 알려져 있다. 본 연구에서는 $In_2O_3$ nanoparticle의 density를 조절하여 첨가함으로써 IGZO TFT 소자 특성에 미치는 평가를 진행하였다. $In_2O_3$ nanoparticle의 density변화에 따른 interparticle spacing과 IGZO계면 사이의 미세구조와 전기적인 특성간의 상관관계를 연구하기 위하여 IGZO TFT 특성은 HP 4145B 측정을 통하여 확인하였고, $In_2O_3$ nanoparticle의 분포와 결정성은 AFM과 XRD, TEM을 통해 분석하고 In2O3 nanoparticle의 유무에 따른 IGZO channel 층의 조성 변화를 STEM과 AES를 통해 비교 및 분석하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.194-197
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• 2002

Applying dual layer insulator on plastic substrates improved electrical characteristics of organic thin film transistor(TFT). A high-quality silicon dioxide(SiO$_2$) suitable for a insulator was deposited on plastic substrates by e-beam evaporation at 110$^{\circ}C$. The insulator film which was treated by N$_2$ annealing at 150$^{\circ}C$ showed excellent I-V, C-V characteristics. The dual layer insulator structure of polyimide-SiO$_2$ improved the roughness of SiO$_2$ surface and showed very low leakage current. In addition, the flat band voltage has been reduced from -2.5V to about 0.5V.