• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.769-772
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• 2014

비정질 InGaZnO 박막트랜지스터의 Gate Overlap 길이에 따른 NBS(Negative Bias Stress) 및 hot carrier 스트레스 후 시간별 문턱전압의 변화에 의한 소자신뢰도를 분석하였다. 측정에 사용된 소자는 비정질 InGaZnO TFT이며 채널 폭 $W=104{\mu}m$, 게이트 길이 $L=10{\mu}m$이며 Gate Overlap 길이는 $0,1,2,3{\mu}m$를 사용하였다. 소자 신뢰도는 전류-전압을 측정하여 분석하였다. 측정 결과, hot carrier 스트레스 후 Gate Overlap 길이가 증가할수록 문턱전압의 변화가 증가하였다. 또한, NBS 후에는 Gate Overlap 길이가 증가할수록 문턱전압의 변화가 감소하였고 장시간 스트레스 후에 hump가 발생하였다.

• 대한전자공학회논문지SD
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• 제49권1호
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• pp.1-7
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• 2012

산화물 박막트랜지스터를 이용하여 액정 디스플레이 패널에 내장할 수 있는 새로운 게이트 드라이버 회로를 설계하고 제작하였다. 산화물 박막트랜지스터는 문턱전압이 음의 값을 갖는 경우가 많기 때문에 본 회로에서는 음의 게이트 전압을 인가하여 트랜지스터를 끄는 방법을 적용하였다. 또한 세 개의 풀다운 트랜지스터를 병렬로 배치하고 번갈아 사용하므로 안정적인 동작이 가능하다. 제안한 회로는 트랜지스터의 문턱전압이 -3 V ~ +6 V인 범위에서 정상적으로 동작하는 것을 시뮬레이션을 통해서 확인하였으며, 실제로 유리 기판 상에 제작하여 안정적으로 동작하는 것을 검증하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1301-1304
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• 2007

We have investigated degradation of short channel n-type poly-Si TFTs with LDD under high gate and drain voltage stress due to self-heating. We have found that the threshold voltage of short channel TFT is shifted to negative direction on the selfheating stress, whereas the threshold voltage of long channel is moved to positive direction.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1701-1703
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• 2006

Here we describe a novel driving scheme in the form of negative AC bias stress (NAC) to compensate shift in the threshold voltage for hydrogenated amorphous silicon (${\alpha}$-Si:H) thin film transistor (TFT) for AMOLED applications. This scheme preserves the threshold voltage shift of ${\alpha}$-Si:H TFT for infinitely long duration of time(>30,000 hours) and thereby overall performance, without using any additional TFTs for compensation. We briefly describe about the possible driving schemes in order to implement for real time AMOLED applications. We attribute most of the results based on concept of plugging holes and electrons across the interface of the gate insulator in a controlled manner.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.3-3
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• 2010

We investigated the influence of the indium content on the threshold voltage ($V_{th}$) shift of sol-gel-derived indium-gallium-zinc oxide (IGZO) thin film transistors (TFTs). Surplus indium composition ratio into IGZO decreases the value of $V_{th}$ of IGZO TFTs showed huge $V_{th}$ shift in the negative direction. $V_{th}$ shift decreases from 10 to -28.2V as Indium composition ratio is increased. Because the free electron density is increased according to variation of the Indium composition ratio.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권3호
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• pp.158-166
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• 2001

Based on uniform hot carrier injection (optically assisted electron injection) across the $Si-SiO_2$ interface into the gate insulator of n-channel IGFETs, the threshold voltage shifts associated with electron injection of $1.25{\times}l0^{16}{\;}e/\textrm{cm}^2 between 0.5 and 7 MV/cm were found to decrease from positive to negative values, indicating both a decrease in trap cross section ($E_{ox}{\geq}1.5 MV/cm$) and the generation of FPC $E_{ox}{\geq}5{\;}MV/cm$). It was also found that FNC and large cross section NETs were generated for $E_{ox}{\geq}5{\;}MV/cm$. Continuous, uniform low-field (1MV/cm) electron injection up to $l0^{19}{\;}e/\textrm{cm}^2 is accompanied by a monatomic increase in threshold voltage. It was found that the data could be modeled more effectively by assuming that most of the threshold voltage shift could be ascribed to generated bulk defects which are generated and filled, or more likely, generated in a charged state. The injection method and conditions used in terms of injection fluence, injection density, and temperature, can have a dramatic impact on what is measured, and may have important implications on accelerated lifetime measurements.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권6호
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• pp.546-550
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• 2013

We propose a novel negative differential resistance (NDR) device with ultra-high peak-to-valley current ratio (PVCR) by combining pn junction diode with depletion mode nanowire (NW) transistor, which suppress the valley current with transistor off-leakage level. Band-to-band tunneling (BTBT) Esaki diode with degenerately doped pn junction can provide multiple switching behavior having multi-peak and valley currents. These multiple NDR characteristics can be controlled by doping concentration of tunnel diode and threshold voltage of NW transistor. By designing our NDR device, PVCR can be over $10^4$ at low operation voltage of 0.5 V in a single peak and valley current.

• 한국전기전자재료학회논문지
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• 제24권8호
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• pp.674-677
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• 2011

The dependency of sputtering power on the electrical performances in amorphous HIZO-TFT (hafnium-indium-zinc-oxide thin film transistors) has been investigated. The HIZO channel layers were prepared by using radio frequency (RF) magnetron sputtering method with different sputtering power at room temperature. TOF-SIMS (time of flight secondary ion mass spectrometry) was performed to confirm doping of hafnium atom in IZO film. The field effect mobility (${\mu}FE$) increased and threshold voltage ($V_{th}$) shifted to negative direction with increasing sputtering power. This result can be attributed to the high energy particles knocking-out oxygen atoms. As a result, oxygen vacancies generated in HIZO channel layer with increasing sputtering power resulted in negative shift in Vth and increase in on-current.

• 전자공학회논문지A
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• 제30A권6호
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• pp.14-21
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• 1993

MODFETs using the heterostructure of phosphorous-contained a-SiN:H: and undoped a-Si:H films have been fabricated by PECVD of SiH$_{4}$, PH$_{3}$ gases. Thecharacteristics of the devices have been invetigated and compared with conventional TFTs(CTFTs). The threshold voltage of the MODFETs was smaller than that of CTFTs, in the case of the devices using the a-SiN:H film with the relatively high phosphorous content, the threshold voltage was negative and the operation of the devices followed the depletion mode. On the other hand, on/off current ratio of the MODFETs was more than one order of magnitude higher than the CTFTs, and the field effect mobility of the former was approximately two times as high as that of the latter.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.257-260
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• 2007

Hydrogenated amorphous silicon thin film transistors were fabricated on a flexible metal substrate. A negative voltage at a floated gate can be induced by a negative substrate bias through a capacitor between the substrate and gate electrode. This can recover the shifted-threshold voltage to an original value.